Oak trees conjure images of mighty trees with broad crowns, thick trunks, adorable acorns, and beautiful shiny green, lobed leaves that provide rich shade.
That, in a nutshell, is how to describe an oak. Pun intended since oaks produce nuts.
Oaks are in the Quercus genus within the Fagaceae or beech family of trees.
There are about 480 species of oaks found throughout the northern hemisphere. Many of them are mighty oaks, but many are also shrubs.
North America has the largest number of oaks in the world, with about 160 species in Mexico, 109 of which are endemic. The USA has about 90 oaks.
Other “oak” trees include the Stone Oak (Lithocarpus) of Australia and the Silver Oak of the Proteaceae family.
Since Quercus is such a massive genus, we will focus on learning the different types of true oak trees and how to identify them.
Guide to Oak Tree Varieties – 36 Types and How to Identify Them
The Quercus genus is a large genus with a lot of variability, so it has been split into subgenera and sections, which makes it easier to see the similarities and relationships between species.
While many people simply classify oaks into “red” and “white” oak types, there are actually many more types of oaks out there that don’t fit in either of those classes.
Let’s break it down into the two subgenera, Quercus and Cerris, and then again into the sections they are divided into.
Subgenus Quercus – New World or High Latitude Clade – Mostly Native to North America
The subgenera that Quercus are divided into, Quercus and Cerris, are determined largely by modern molecular phylogenetic evidence and pollen characteristics that require strong magnification to determine.
However, one distinguishing factor is that subgenus Quercus contains all North American oaks, and North America has the highest diversity of oaks in the world, so it’s a big subgenus.
Subgenus Quercus is further divided into five sections, two of which are the red and white oak categories.
We will discuss four of those sections below.
A. Section Lobatae – North American Red Oaks
Oaks in the red oak group or Section Lobatae typically, but not always, have leaves with pointed lobes tipped with bristly awns.
They are often fast-growing, mostly deciduous trees.
Their acorns are biennial, taking two years to mature and sprout. The inner surfaces of their cupules are typically hairy, and most produce very bitter seeds high in tannins, although a few produce edible nuts.
Some red oaks are known for their fall color displays which can be red, burgundy, copper, or bronze.
1. Red Oak – Quercus rubra
Red Oak is one of the most common oaks in the eastern half of the USA. It is one of the many oaks that expanded in numbers following the collapse of the American Chestnut, replacing it structurally and as a food source for many animals.
Their leaves are typical of the red oak section with 7 – 11 pointy lobes.
It is a relatively fast-growing tree, making it a popular landscape choice.
Best grown in full sun in average, moderately acidic soil with medium moisture.
If you live in eastern North America, this might be the perfect tree for you; it’s fast-growing, beautiful, and native.
However, Red Oak is one of the most common invasive trees in temperate European forests.
With so many oaks to choose from worldwide, you should have no problem finding a suitable native one in your area.
Identifying Features of the Red Oak
Red Oaks are medium-tall deciduous trees with rounded or spreading crowns, often made of contorted branches.
The bark is gray or brownish, with wide ridges and shallow furrows.
They can be identified by leaves that are ovate, elliptic, or obovate, 4.7 – 7.8” long, about half as wide, with a broadly cuneate to almost truncate base and acute tips. Margins have 7 – 11 oblong lobes and 12 – 50 awns, with sinuses extending less than ½ the distance to the midrib.
Lower leaf surfaces are pale green, often glaucous, and mostly hairless except for tufts in axils; upper surfaces are dull green and hairless. Secondary veins are raised on both surfaces.
Acorns have saucer- to cup-shaped cupules, 0.2 – 0.5” high, covering ¼ – ⅓ of the nut, with tightly appressed puberulent scales that often have dark margins.
Nuts are ovoid to oblong, hairless, 0.6 – 1.2” long, and about ⅔ as wide.
Often Confused With: Red Oak is mostly confused with Black Oak which is a smaller tree that prefers dryer habitats and has more dark green glossy foliage, usually with fewer, more variable lobes and acorns whose cupules cover ½ the nut with fewer, larger, loose pubescent scales. Sometimes it is confused with White Oak, which has scaly bark and larger leaves with shallowly to deeply rounded lobes that don’t have awns.
Other Common Names: Common Red Oak, Eastern Red Oak, Mountain Red Oak, and Gray Oak.
Native Area: Eastern North America from Ontario east to Prince Edward Island, Canada, and in the USA from Minnesota southeast to Oklahoma, and east to Georgia and North Carolina.
USDA Growing Zones: 5 – 9
Average Size at Maturity: 50 – 70 ft (to 90 ft) tall, 40 – 60 ft spread
Available at: Fast-Growing-Trees & Nature Hills
2. Black Oak – Quercus velutina
Black Oak is a medium-sized tree with glossy leaves that appear light green in spring and become glossy dark green in summer, making a gorgeous shade, street, or border tree.
It gets its common name from its dark gray, rough bark that appears nearly black at times.
Best grown in full sun in moist, rich, acidic, well-drained soil for growing taller trees.
It also easily tolerates poor-quality and dry soils, better so than the Red Oak; it will just grow slower and not reach as tall when grown in poorer conditions.
Plant it in its permanent location while it is young since its deep taproot makes transplanting larger specimens very difficult to do successfully.
This is another of the more common oak tree varieties.
Identifying Features of the Black Oak
Black Oak is a medium or rarely tall deciduous tree with a broadly rounded or spreading crown.
The rough bark is nearly black, often with deep vertical furrows and horizontal cracks creating rectangular cross-checking.
Leaves are ovate, obovate, or elliptic, 4 – 10” long, glossy dark green with cuneate to truncate bases.
Margins are 5 – 7-lobed and may be cut shallowly (shade leaves) or deeply (sun leaves) to ⅔ of the way to the midrib and have strong awns on their tips.
Lower leaf surfaces are hairless or loosely stellate, with pubescent tufts in vein axils; midveins on the upper surface are loosely stellate to hairless. Young leaves are conspicuously stellate.
Acorns are 0.6 – 0.8” long with turbinate cupules covering ½ the nut with relatively few large, pubescent, loose scales on the outside that form a marginal fringe.
Often Confused With: Black Oak is often confused with Red Oak which is usually a larger tree with leaves that are medium green and less glossy, cupules that cover only ¼ – ⅓ of the nut, smaller cupule scales that are hairless and tightly appressed; it also grows in more moist habitats.
Other Common Names: Yellow Oak, Quercitron Oak, Yellow-Bark Oak, and Smooth-Bark Oak.
Native Area: Eastern North America from Nebraska south to Texas, east to northern Florida, north to Minnesota, east to Maine, USA, plus extreme southern Ontario, Canada.
USDA Growing Zones: 3 – 9
Average Size at Maturity: 50 – 60 ft (to 130 ft) tall, 50 – 60 ft spread
Available at: Nature Hills
3. Willow Oak – Quercus phellos
When most people picture an oak, they think of large, lobed leaves, but the Willow Oak gets its name from its thin, straight leaves that look like willow trees, making it easily identified.
It is a medium to somewhat tall tree that adapts well to urban environments where it is often used as a street tree or for borders along busy highways.
While dormant, it transplants easily thanks to its fibrous root system.
It produces fewer, smaller acorns for less mess than most other oaks, making it suitable as a specimen tree where low maintenance is required.
It naturally grows in moist, alluvial soils along creeks, rivers, valleys, etc.
Best grown in full sun in moist, well-drained, acidic soil. Acidic soil is important to keep your tree healthy and problem-free.
It is somewhat drought-tolerant once established.
Identifying Features of the Willow Oak
Willow Oak is a medium or sometimes tall tree with smooth dark gray bark that becomes irregularly fissured with age.
Leaves are linear to narrowly elliptic, 2 – 4.75” long, 0.4 – 1” wide, with a cuneate base and an acute tip with an apical awn. Margins are entire, without lobes or teeth.
Lower leaf surfaces are pale green, hairless, or rarely pubescent, and upper surfaces are light green and hairless.
Acorns have shallowly saucer-shaped cupules 0.1 – 0.25” high, covering ¼ – ⅓ of the nut with tightly appressed puberulent scales.
The nut is ovoid to hemispheric, 0.3 – 0.5” long, and nearly as wide, often striated, and hairless.
Often Confused With: Willow Oak is mostly confused with Swamp Laurel Oak, which has very similar but usually wider leaves that are more rhombic or broadly elliptic and have obtuse or rounded tips, and its acorn cupules cover ¼ to ½ of their nuts that are never striated. Sometimes it’s confused with Water Oak, which has larger, wider leaves that are usually obtrullate with obtuse, blunt, or rounded tips and are entire or lobed and have tufts of hairs in the vein axils on their lower surfaces.
Other Common Names: Peach Oak, Pin Oak, and Swamp Chestnut Oak.
Native Area: Endemic to southeastern USA from Oklahoma south to Texas northeast to New Jersey and south to northern Florida.
USDA Growing Zones: 6 – 9
Average Size at Maturity: 40 – 60 ft (to 100 ft) tall, 30 – 40 ft spread
Available at: Fast-Growing-Trees & Nature Hills
4. Water Oak – Quercus nigra
Water Oak, as the name implies, is adapted to live in wet, swampy areas.
They also grow in well-drained sites and even heavy, compacted soils where most trees will not grow well.
It is often grown commercially as a shade or ornamental tree for its spreading canopy of leaves, its fast growth (more than 24” per year), and its ease of transplanting.
Best grown in full sun or partial shade with at least four hours of direct sun per day in acidic, loamy, sandy, or clay soils that are wet or well-drained.
It is intolerant of severe drought.
In the fall, its foliage turns a showy yellow.
Their acorns are a food source for squirrels, white-tailed deer, raccoons, wild turkeys, waterfowl, and quail. In the winter, deer eat the buds and young twigs.
Identifying Features of the Water Oak
Water Oak is a medium to tall tree with a conical crown becoming rounded or spreading.
The bark is grayish-black with shallow, irregular fissures.
This oak is identified by leaves are deciduous (sometimes tardily) dull bluish-green to dark green, distinctly obtrullate, rarely elliptic or obovate, 1.2 – 6.3” long, half as wide, with an attenuate, cuneate, or rarely rounded base and obtuse, blunt, or rounded tips.
Leaf margins are entire with an apical awn or shallowly 2 – 3-lobed with 2 – 5 awns.
Lower leaf surfaces are mostly hairless except for tufts in vein axils; veins are rarely raised. Upper surfaces are hairless with somewhat impressed secondary veins.
Acorns have saucer-shaped cupules less than ¼” high that covers ¼ or less of the nut and have puberulent, tightly appressed scales.
Nuts are 0.37 – 0.55” long, equally as wide, hairless, and often striated with brown and black.
Often Confused With: Water Oak is mostly confused with Blackjack Oak, which is a smaller tree with larger leaves with 3 – 5 broad and shallow lobes with 3 – 10 awns, scurfy or rusty pubescent lower leaf surfaces, and secondary veins that are raised on both surfaces. It’s also confused with Southern Red Oak, which has ovate, elliptic, or obovate leaves that are larger and have 3 – 7 more deeply cut lobes with 6 – 20 awns and secondary veins that are raised on both surfaces.
Other Common Names: Possum Oak, Spotted Oak, Duck Oak, Punk Oak, and Orange Oak.
Native Area: Endemic to the southeastern USA from east Texas north to eastern Oklahoma, northeast to New Jersey, and south to southern Florida.
USDA Growing Zones: 5 – 9
Average Size at Maturity: 50 – 80 ft tall, 50 – 80 ft spread
Available at: Nature Hills
5. Pin Oak – Quercus palustris
The Pin Oak is a popular North American native widely used shade tree for its relatively fast growth and uniform shape.
A fairly common oak tree, it is moderately tall and provides enormous wildlife value. Its acorns are loved by wildlife, and it hosts over 150 native insects that will also attract countless birds.
It grows naturally in full sun in moist valley bottoms or moist uplands in acidic soil.
Best grown in full sun in moist to medium well-drained loam, sandy loam, or clay soils that are mildly acidic.
It can tolerate occasional flooding and will grow in poorly drained soils.
It gets its name from the new twigs that grow along their branches that are small, stiff, and sharp like a pin when they first appear.
Leaves are deciduous but typically marcescent, remaining dead on the tree until spring.
Identifying Features of the Pin Oak
Pin Oak is a medium or sometimes tall deciduous tree with persistent lower branches that are slender and widely spreading.
The bark is either smooth or has shallow furrows and flat ridges when mature.
Leaves are more or less elliptical, 3 – 6” long, with cuneate and decurrent bases and 5 – 7 deeply cut lobes with rounded or U-shaped sinuses. Lobes are often widened at the tip, toothed, and have awn-tipped teeth and tips.
Upper leaf surfaces are glossy green, and lower surfaces are pale green and hairless except for conspicuous tufts of stellate hairs in vein axils.
Acorn cupules are saucer-shaped, 0.4 – 1” wide, covering ¼ to ⅓ of the nut with very small and tightly appressed puberulent scales.
The nut is 0.4 – 0.55” long and wide, round or somewhat round, and is sometimes striated with bands of darker and lighter brown.
Often Confused With: Pin Oak is mostly confused with Scarlet Oak (Qercus coccinea), which has elliptical, ovate, or obovate leaves of similar size but are lighter green and have 5 – 9 deeply cut lobes and secondary veins raised on both surfaces; its acorns have cupules that cover ⅓ to ½ of the oblong to somewhat rounded nuts and are often tuberculate. It is also confused with the Northern Pin Oak (Quercus ellipsoidalis), which often has stubs of branches on its lower trunk not seen in Pin Oak, and its lighter green leaves have 5 – 7 lobes that are more deeply cut.
Other Common Names: Swamp Oak, Water Oak, and Swamp Spanish Oak.
Native Area: Northeastern North America from Iowa southeast to eastern Kansas and northeastern Oklahoma, east to Vermont (including extreme southern Ontario, Canada), and south to North Carolina.
USDA Growing Zones: 4 – 8
Average Size at Maturity: 60 – 80 ft (to 100 ft) tall, 40 – 60 ft spread
Some Cultivars Available:
- Pacific Brilliance™ Pin Oak Quercus palustris ‘PWJR08’ is a medium-sized oak growing to about 50 ft tall but only half as wide, with large, medium green leaves with thick veins, pointy margins, and silvery undersides that shimmer in the sunlight. – Image via Nature Hills and Kuenzi Turf Nursery – Combined by Lyrae Willis for Tree Vitalize.
Available at: Fast-Growing-Trees & Nature Hills
6. Swamp Laurel Oak – Quercus laurifolia
Swamp Laurel Oak is another oak with leaves that are atypical for an oak, being shaped more like a laurel than an oak leaf.
It is a large, relatively fast-growing shade tree with a dense, oval crown, growing taller than it does wide.
It has a wide trunk that strongly flares at the base and can lift sidewalks or other foundations if not planted at least 8 ft away.
It grows naturally in moderately dry to seasonally flooded lowlands, particularly along swamp margins, giving it its common name.
Performs best in full sun to partial shade in rich, humusy, acidic soils that are wet to medium well-drained.
It is susceptible to breakage, and pruning may be required to keep the tree healthy and shapely.
Identifying Features of the Swamp Laurel Oak
Swamp Laurel Oaks are medium to tall trees with thick trunks that flare at the base.
The bark is dark brown to black with flat ridges and deep furrows.
Leaves are deciduous or tardily deciduous, rhombic or broadly elliptic to obovate, occasionally oblong or spatulate, 1.2 – 4.75” long, 0.6 – 1.8” wide, with an attenuate, cuneate, or rarely obtuse base and obtuse or rounded tip. Margins are entire with an apical awn.
Lower leaf surfaces are hairless, and upper leaf surfaces have raised veins.
Acorns have shallowly saucer-shaped to deeply bowl-shaped cupules 0.14 – 0.35” high, about ½” wide, covering ¼ to ½ of the nut with puberulent tightly appressed scales.
The nuts are rounded or broadly ovoid, hairless, 0.33 – 0.63” long, and about as wide.
Often Confused With: Swamp Laurel Oak is mostly confused with Willow Oak, which has similar-sized leaves, but they’re usually lighter green and narrower with cuneate bases and acute tips; their acorns also have more shallow cupules that only cover ¼ to ⅓ of the slightly shorter and usually striated nut.
Other Common Names: Laurel Oak, Darlington Oak, Diamond-Leaf Oak, Laurel-Leaf Oak, and Water Oak.
Native Area: Endemic to southeastern USA along the Atlantic and Gulf Coastal Plains from southeastern Texas east to southern Florida and north to Virginia.
USDA Growing Zones: 6 – 10
Average Size at Maturity: 60 – 70 ft (to 130 ft) tall, 35 – 45 ft spread
7. Blackjack Oak – Quercus marilandica
Blackjack Oak is a handsome small oak with a compact form and rich canopy of dark glossy green foliage that provides great shade.
It often naturally grows in scruffier forms in poor soils in barren open fields, edges of woodlands, and dry ridges.
Best grown in dry to medium moist, well-drained acidic soils in full sun.
It tolerates poor soils and drought well but is intolerant of poorly drained wet soils.
It gets its name from its showy leathery dark green blackjack-like leaves.
The fall color is a yellow-brown to russet color.
Identifying Features of the Blackjack Oak
Blackjack Oak is a small to medium-sized tree with an irregular to spreading crown.
The bark is nearly black, with rough, irregular, or rectangular scaly blocks when mature.
Leaves are obovate to obtrullate, to 2.75” (2”) – 7.75” long and about as wide with a rounded or cordate, but not decurrent base and acute to obtuse or rarely rounded tips.
Leaf margins have 3 – 5 shallow, often very broad lobes with 3 – 10 awns.
Lower leaf surfaces are scurfy or with scattered, often rusty, pubescence. The upper surfaces are leathery, glossy green, and hairless. Secondary veins are raised on both surfaces.
Acorns are biennial with turbinate cupules 0.24 – 0.4” high, 0.5 – 0.7” wide, covering ⅓ of the nut with puberulent scales that are often rather loose, especially near the rim.
Nuts are broadly ovoid or ellipsoid and are often striated.
Often Confused With: Blackjack Oak is mostly confused with the Southern Red Oak, which is a taller tree with ovate, elliptic, or obovate leaves that are often much larger with 3 – 7 more deeply cut lobes with 6 – 20 awns and a terminal lobe that is often much longer than rest; its acorns have shallower cupules with tightly appressed scales that cover ⅓ to ½ the smaller, more rounded nuts.
Other Common Names: Barren Oak, Scrub Oak, Black Oak, and Jack Oak.
Native Area: Endemic to the southeastern USA from east Kansas south to east Texas, northeast to New Jersey, and south to northern Florida.
USDA Growing Zones: 6 – 9
Average Size at Maturity: 20 – 40 ft (to 50 ft) tall, 20 – 40 ft spread
Available at: Nature Hills
8. Southern Red Oak – Quercus falcata
Southern Red Oak is a medium to large shade tree with a beautiful rounded crown and showy red fall color.
It is popular in the landscaping industry as a shade, lawn, specimen, or street tree.
Best grown in full sun in well-drained, acidic, sandy, or clay loam soils. It will tolerate poor soils and some partial shade but not full shade.
It is drought-tolerant once established but will also tolerate occasional flooding, provided it is not persistent.
It is moderately fast-growing for an oak.
Identifying Features of the Southern Red Oak
Southern Red Oaks are medium to tall deciduous trees with rounded crowns and dark brown to black, narrowly furrowed bark with scaly ridges.
Leaves are ovate, elliptic, or obovate, 3.9 – 11.8” long, ⅓ to ½ as wide, with a rounded, somewhat cuneate, or sometimes oblique base and acute tips.
Leaf margins have 3 – 7 deeply cut lobes and 6 – 20 awns. The terminal lobe is often long-acuminate and much longer than the lateral lobes.
Lower leaf surfaces are tawny-pubescent; upper surfaces are glossy and hairless or sometimes puberulent along the midrib. Secondary veins are raised on both surfaces.
Acorns have saucer-shaped to cup-shaped cupules 0.11 – 0.28” high, 0.35 – 0.7” wide, covering ⅓ to ½ of the nut with puberulent tightly appressed scales.
The nut is somewhat round, 0.35 – 0.63” long, nearly as wide, often striate, and puberulent.
Often Confused With: Southern Red Oak is mostly confused with Blackjack Oak, which is a smaller tree with obovate to obtrullate leaves that are often smaller with more shallowly 3 – 5-lobed margins with only 3 – 10 awns, and its acorns have taller cupules that cover ⅓ of the broadly ovoid or elliptical nuts.
Other Common Names: Spanish Oak, Water Oak, Red Oak, and Cherrybark Oak.
Native Area: Endemic to the southeastern USA from eastern Texas and Oklahoma northeast to Virginia and south to northern Florida.
USDA Growing Zones: 6 – 9
Average Size at Maturity: 60 – 80 ft tall, 40 – 50 ft spread
Available at: Fast-Growing-Trees & Nature Hills
9. Shumard Oak – Quercus shumardii
Shumard Oak is one of the larger trees of the red oak group with gorgeous red fall color, making it a popular choice for landscaping where it has room for it to grow.
It is often grown as a shade tree in yards, streets, parks, and other open spaces.
It is relatively fast-growing, highly adaptable, and drought-tolerant. It also tolerates short-term floods and strong winds.
It naturally grows in rich, moist clay soils alongside streams and swamps.
Best grown in average, deep, moist soil in full sun.
Identifying Features of the Shumard Oak
Shumard Oak is a relatively tall tree with a broadly rounded or spreading crown.
The bark is gray-brown to dark brown, with shallow furrows and scaly, light-colored flat ridges.
Leaves are broadly elliptic to obovate, 3.9 – 7.9” long, about ⅔ as wide, with obtuse to truncate or occasionally cuneate bases. Margins are 5 – 9-lobed with 15 – 50 awns; lobes are oblong to distally expanded with acute tips.
Lower leaf surfaces are hairless except for conspicuous tomentose tufts in vein axils; upper surfaces are glossy and hairless. Secondary veins are raised on both surfaces.
Acorns have saucer-shaped to cup-shaped cupules 0.28 – 0.47” high, 0.6 – 1.2” wide, covering ¼ to ⅓ of the nut with hairless to puberulent tightly appressed scales that often have pale margins.
Nuts are ovoid to oblong, hairless, occasionally nearly rounded, 0.55 – 1.2” long, and about ⅔ as wide.
Often Confused With: Shumard Oak is mostly confused with Red Oak, which has slightly narrower ovate, elliptic, or obovate leaves with 7 – 11 lobes that are duller green and often glaucous on the lower surface, and its cupules usually have scales with dark margins. It’s also confused with Buckley’s Oak (Quercus buckleyi) which is a smaller tree that usually has smoother bark, smaller and broader leaves, cupules covering ⅓ to ½ of the nut, and appressed scales that are sometimes tuberculate near the base.
Other Common Names: Spotted Oak, Schneck Oak, Shumard Red Oak, and Swamp Red Oak.
Native Area: Endemic to eastern USA from central Texas north to east Kansas, east to Indiana and Ohio, and south to northern Florida with disjunct populations in Michigan, New York, and Virginia.
USDA Growing Zones: 4 – 8
Average Size at Maturity: 40 – 60 ft (to 115 ft) tall, 40 – 60 ft spread
Available at: Fast-Growing-Trees & Nature Hills
10. Sierra Madre Red Oak – Quercus albocincta
The Sierra Madre Oak is one of over 100 oaks that are endemic to Mexico, found nowhere else in the world.
Unlike many of the Mexican oaks, however, this one has a broader range, and its population has not suffered as much from habitat decline and fragmentation compared to some Mexican oaks.
It is a small deciduous tree with a lovely, elegantly spreading crown and stiff, leathery green leaves that provide great summer shade.
It grows naturally in poor-quality, acidic soils on steep mountain slopes throughout its range, where it is a common species in the Sierra Madres.
Best grown in full sun in any average, well-drained soil. It likely will not tolerate wet soils.
Their nuts are much lower in tannins than most red oaks, making them sweet-tasting and edible. Locals occasionally harvest them.
Identifying Features of the Sierra Madre Red Oak
Sierra Madre Red Oak is a small to medium-sized deciduous tree with an oval to spreading crown and chestnut brown bark.
Leaves are stiff, leathery, elliptical, or more or less broadly ovate, up to 6.5” long with variable bases and long-acuminate tips.
Leaf margins are thickened and revolute, unlobed but with 3 – 6 pairs of large serrate to dentate teeth with awned tips that are often quite long (to ½”).
Young leaves are pubescent on both surfaces, becoming hairless and glossy when mature other than short hairs along the upper midrib and tufts in the lower vein axils. Secondary veins are raised on the lower surface.
Acorns are ovoid, 0.4 – 0.75” long, up to 0.4” wide, single, or in clusters. Cupules are hemispherical, nearly sessile, with tightly appressed scales that cover nearly ½ of the nut.
Often Confused With: Sierra Madre Red Oak is mostly confused with Quercus tuberculata, another Mexican endemic that grows to a similar size with similar-sized leathery green leaves, but it can be differentiated quickly by its leaf margins that are undulate and entire (never have teeth).
Other Common Names: N/A
Native Area: Endemic to Mexico in the Sierra Madre Occidental of Sonora, Chihuahua, Durango, and Sinaloa, and also in southern Baja California Sur.
USDA Growing Zones: 7 – 10
Average Size at Maturity: 10 – 50 ft tall, 10 – 40 ft spread
11. Texana Nuttall Oak – Quercus texana
The Texana Nuttall Oak is a large deciduous tree with a broadly rounded crown.
It has lovely dark green foliage consisting of leaves that are deeply divided into pointy lobes. The fall color arrives late but rewards you with a brilliant red to red-orange late fall and early winter color display.
It is a fast-growing, low-maintenance tree that transplants well.
Best grown in full sun in average soil; grows equally well in well-drained or wet soils.
The wood is often used for lumber.
Waterfowl, wild turkeys, squirrels, deer, and other small mammals love to feast on the acorns.
Identifying Features of the Texana Nuttall Oak
Texana Nuttall Oaks are medium-sized deciduous trees with broadly rounded crowns and dark brown bark with flat ridges and shallow fissures.
Leaves are ovate, elliptic, or obovate, 3 – 7.9” long, about ⅔ as wide, with cuneate to almost truncate bases that are often oblique. Margins are usually deeply divided into 6 – 11 oblong to distally expanded or rarely falcate lobes with acute tips and 9 – 24 awns.
Lower leaf surfaces are hairless except for conspicuous tomentose tufts in the axils of its raised veins; upper leaf surfaces are hairless.
Acorns have deeply goblet-shaped cupules with a constriction at the base and are 0.4 – 0.6” high, 0.6 – 0.86” wide, covering ⅓ to ½ of the nut with hairless to sparsely puberulent tightly appressed scales.
Nuts are broadly ovoid to broadly ellipsoid, 0.6 – 1” long, nearly as wide, and hairless to sparsely puberulent.
Often Confused With: Texana Nuttall Oak is mostly confused with Buckley’s Oak (Quercus buckleyi), which is a small tree often with smoother bark, smaller, broader, and often rounded leaves with 7 – 9 lobes and 12 – 35 awns; its cupules are sometimes tuberculate near the base.
Other Common Names: Spanish Oak, Nuttall’s Oak, Texas Red Oak, Spotted Oak, Rock Oak, and Red River Oak.
Native Area: Endemic to southcentral USA from southeast Missouri south to east Texas, east through to Alabama, and north to extreme western Tennessee.
USDA Growing Zones: 8 – 9
Average Size at Maturity: 30 – 50 ft (to 82 ft) tall, 35 – 40 ft spread
Available at: Nature Hills
12. Coast Live Oak – Quercus agrifolia
Coast Live Oak is a gorgeous small to medium-sized tree with a graceful spreading crown that makes a beautiful specimen tree.
Even though it is part of the red oak group, it is slow-growing and has annual acorns, more like those in the white oak group.
Their entire (not lobed) evergreen leaves are glossy rich green, providing year-round shade and cover for animals.
Best grown in average, well-drained soil in full sun.
It is highly drought-tolerant once established, thriving in Mediterranean-style climates like its endemic habitat in California and Baja California.
Butterflies, birds, and countless animals use this tree for food and habitat.
Identifying Features of the Coast Live Oak
Coast Live Oak is a small to medium-sized evergreen tree with contorted branches and gray to dark brown or black bark with broadly rounded ridges or sometimes cross-checked blocky plates.
Leaves are broadly elliptic, ovate, or oblong, 0.6 – 3” long, ½ to ⅔ as wide, with rounded or cordate bases and blunt to long-acuminate tips. Margins are entire or spinose with up to 24 awns.
Lower leaf surfaces are hairless or with small tomentose tufts in the axils of their raised veins. Upper surfaces are distinctly convex, rugose, hairless, or sometimes pubescent.
Acorns are annual with turbinate to cup- or bowl-shaped, or rarely saucer-shaped cupules 0.35 – 0.5” wide and high, covering ¼ to ⅓ (rarely ½) of the nut with hairless to sparsely puberulent loose scales.
Nuts are ovoid to oblong or conical, 0.5 – 1.4” long and ⅜ – ⅔ as wide, and hairless.
Often Confused With: Coast Live Oak is mostly confused with California Scrub Oak (Quercus berberidifolia), which has gray, scaly bark and obovate, elliptic, or somewhat rounded leaves that are bicolored, only sometimes convex, with glaucous lower surfaces with glandular hairs, and margins that are toothed and spinose, rarely entire.
Other Common Names: California Live Oak, West Coast Live Oak
Native Area: Narrow endemic of southern coastal North America in California, USA, from Mendocino County south to northern Baja California, Mexico.
USDA Growing Zones: 8 – 10
Average Size at Maturity: 25 – 50 ft (to 82 ft) tall, 15 – 35 ft spread
Available at: Fast-Growing-Trees
B. Section Quercus – White Oak Species
White Oaks are mostly native to North America, but several Eurasian species also fall into the Subgenus Quercus Section Quercus group.
The leaves on white oak trees are typically, but not always, rounded and smooth and tend not to have awns.
Their acorns mature in one year, and they sprout soon after they fall to the ground. Their acorns are often sweeter, with more species considered edible than red oaks.
They tend to be slower-growing trees and produce somewhat harder and more dense wood.
13. White Oak – Quercus alba
White Oak is a common mighty oak tree throughout much of eastern North America, providing important structural diversity to forests and food and habitat for countless wildlife.
They are medium to large trees with wide, spreading crowns and beautiful rounded-lobed light to medium green leaves that make a wonderful shade tree.
In fall, this tree provides stunning fall color when the foliage turns a deep crimson red.
Best grown in full sun in medium moist soil that is acidic.
It does not transplant well, so plant it young in its permanent location.
It is a slow-growing tree with a wide trunk that flairs at the base, so do not plant it next to a sidewalk or other foundations or structures it could damage over time.
The acorns tend to be less bitter than most oaks and are occasionally eaten by humans.
Identifying Features of the White Oak
White Oak is a medium to tall tree with a broad, spreading crown and light gray, scaly bark.
Leaves are obovate to narrowly elliptic, 4.75 – 9” (3.15 – 11”) long, usually ½ to ⅔ as wide, with narrowly to broadly cuneate bases. Margins are moderately to deeply lobed with rounded lobes that are often narrow. Sinuses extend ⅓ – ⅞ the distance to the midrib.
Lower leaf surfaces are light to medium green with whitish or reddish hairs when young, becoming hairless. Upper surfaces are light gray-green and may be glossy or dull.
Acorns grow in clusters of 1 – 3 that are nearly sessile or on a peduncle up to 2” long with a hemispheric cupule covering ¼ of the nut with finely gray tomentose tightly appressed scales.
The nut is light brown, ovoid-ellipsoid or oblong, hairless, 0.5 – 1” long, and ⅔ to ¾ as wide.
Often Confused With: White Oak is mostly confused with Bur Oak which is a smaller tree with more contorted branching, rougher, deeply furrowed bark, and leathery leaves that are usually longer with a pair of sinuses near the middle that are often cut much deeper than its other lobes and are pale green with stellate hairs on the lower surface. Sometimes it’s confused with English Oak, which has smaller leaves with strongly cordate bases and acorns with a very long, thin 1 – 4” peduncle and cupules that cover ¼ – ¾ of the usually longer and narrower nut.
Other Common Names: American White Oak, Eastern White Oak, Forked-Leaf White Oak, Northern White Oak, and Quebec Oak.
Native Area: Eastern North America from Minnesota south to east Texas and all states east to northern Florida and north to Maine, USA, plus extreme southwestern Quebec, Canada.
USDA Growing Zones: 3 – 9
Average Size at Maturity: 50 – 80 ft tall, 50 – 80 ft spread
Some Cultivars Available (left to right):
- Skinny Genes® Oak Quercus x bimundorum ‘JFS-KW2QX’ is a narrowly columnar tree with strongly fastigiate branches reaching heights of 45 ft tall but only 10 ft wide, making it suitable for landscapes without much room to spread. They can also be planted side by side to create a nice privacy screen. – Image via Nature Hills
- Streetspire® Oak Quercus robur x alba ‘JFS-KW1QX’ is a medium-sized tree up to 45 ft tall with strongly ascending sweeping branches creating a crown only 14 ft wide, making it a great landscape, street, or border tree where there is not as much room to spread. Its lobed leaves turn rustic red in the fall. – Image via Nature Hills.
Available at: Fast-Growing-Trees & Nature Hills
14. Swamp White Oak – Quercus bicolor
Swamp White Oak is another eastern North American native oak that loves low-lying, wet, swampy areas in bottomlands and river valleys.
It is a medium to moderately tall tree that spreads as wide as it does tall, making a fantastic shade tree.
It is a long-lived tree that requires little to no maintenance in the right location.
It has a thick, short trunk that branches low, so if planted next to foot or vehicle traffic, it will likely need pruning for clearance.
Best grown in full sun in moist, acidic to neutral clay, loam, or sand.
While its population is considered secure overall, it has declined dramatically in multiple regions. It is locally listed as Vulnerable to Critically Imperiled in several US states and Canadian provinces.
Identifying Features of the Swamp White Oak
Swamp White Oaks are moderately large trees with short trunks and low-spreading branches.
The bark is dark gray, exfoliating, scaly, or furrowed.
Leaves are obovate to narrowly elliptic, 3.15 – 8.45” long, ½ to ⅔ as wide, with cuneate bases. Margins variable with large rounded teeth, half entire and half toothed, moderately to deeply lobed, or sometimes half lobed and half toothed.
Lower leaf surfaces are light green or whitish with small appressed-stellate hairs and velvety branched hairs; upper surfaces are hairless glossy dark green.
Acorns on a thin peduncle 0.8 – 2.75” long with hemispheric or turbinate cupules 0.4 – 0.5” high, 0.5 – 1” wide, covering ½ – ¾ of the nut with finely grayish tomentose closely appressed scales that are often moderately tuberculate, especially near the rim.
Nuts are light brown, hairless, ovoid-ellipsoid or oblong, 0.5 – 1” long, and about ⅔ as wide.
Often Confused With: Swamp White Oak is mostly confused with Bur Oak, which is a variable shrub or tree with contorted branches and usually larger, leathery leaves with 4 – 7 pairs of lateral lobes with a pair of sinuses near the middle that are often much deeper than the rest; their acorns are also subsessile and usually have much more heavily tuberculate cupules. Sometimes it’s confused with White Oak, but its leaves are always rounded-lobed with often narrow lobes, and its lower surfaces are typically hairless; its acorns are never tuberculate.
Other Common Names: Bicolor Oak, Chêne bicolore (French).
Native Area: Northeastern North America in southern Ontario and Quebec, Canada, plus Minnesota south to Missouri, east to North Carolina, and north to Maine, USA.
USDA Growing Zones: 4 – 8
Average Size at Maturity: 50 – 70 ft (to 100 ft) tall, 50 – 70 ft spread
Some Cultivars Available:
- Beacon Swamp White Oak Tree Quercus bicolor ‘Bonnie and Mike’ is a columnar white oak growing 30 – 35 ft tall but only 12 – 16 ft, making it a suitable choice for small gardens and landscapes without much room to spread. It thrives in rural and urban areas in USDA Zones 4 – 8. – Images via Fast-Growing-Trees – Combined by Lyrae Willis for Tree Vitalize
Available at: Nature Hills
15. Chinkapin Oak – Quercus muehlenbergii
Chinkapin Oak is another oak with atypical leaves for an oak. Instead, they resemble Chestnut trees more than oaks, having smaller glossy yellow-green leaves that are coarsely toothed, much like a chestnut.
Its common name comes from its resemblance to the Ozark Chinkapin chestnut tree.
It is a hardy tree that grows in various climates (USDA Zones 3 – 9) and conditions.
It naturally grows wild on dry bluffs, ridges, and rocky south-facing slopes.
Best grown in full sun in loamy, sandy, clay, or silt soils, provided they are well-drained. They will grow equally well in acidic, neutral, or somewhat alkaline soils.
It is not often grown commercially, but it would make a lovely landscape or shade tree.
Identifying Features of the Chinkapin Oak
Chinkapin Oaks are medium to large trees with rounded crowns or occasionally shrub forms on drier sites.
The gray bark is thin and flaky or papery.
Leaves usually obovate, sometimes lanceolate to oblanceolate, 1.25 – 8.25” long, about ⅓ – ⅔ as wide, leathery, with truncate to cuneate bases. Margins variously undulate, crenate, crenate-serrate, shallow-lobed, or lobed and toothed; tips are rounded, acute, acuminate, or mucronate.
Lower leaf surfaces are glaucous or light green, with minute, appressed stellate hairs; hairless upper surfaces are dark green.
Acorns singly or in pairs, subsessile or on peduncle to 0.3” with a hemispheric or shallowly cupped cupule 0.16 – 0.47” high and twice as wide, covering ¼ to ½ of the nut with gray-pubescent or puberulent, tightly appressed scales that are moderately to prominently tuberculate.
Nuts are light brown, oblong to ovoid, 0.5 – 1” long, and about ⅔ as wide.
Often Confused With: The Chinkapin Oak is mostly confused with the Chestnut Oak (Quercus montana), which has bark with deeply V-shaped furrows, slightly larger, narrowly elliptic or narrowly ovate leaves with often oblique bases, leaf margins that are usually regularly toothed with rounded teeth, and cupules with reddish-tipped hairless scales. Sometimes it’s confused with Swamp Chestnut Oak which has scaly bark, often larger leaves that are regularly crenate or dentate-toothed, and lower surfaces that are velvety to touch with soft, rayed hairs.
Other Common Names: Chinquapin Oak
Native Area: Eastern North America from eastern Kansas, USA, south to northern Mexico (disjunct mountainous populations), east to northern Florida, and north to Vermont.
USDA Growing Zones: 3 – 9
Average Size at Maturity: 40 – 60 ft (10 to 100 ft) tall, 40 – 70 ft spread
Available at: Nature Hills
16. Post Oak – Quercus stellata
The Post Oak gets its common name from its durable wood that was popular for making fence posts and is still sometimes used today.
They are beautiful trees with dense rounded canopies of contorted, spreading branches that would make a beautiful shade or specimen tree.
It grows naturally on dry, sandy soils with low fertility and is extremely drought-tolerant once established.
Best grown in full sun to partial shade in dry to moist but well-drained sandy or rocky acidic soils.
Its large acorns are exceptionally popular with squirrels, deer, and other wildlife.
Identifying Features of the Post Oak
Post Oaks are small to large trees with rounded crowns, sinuous trunks, contorted branches, and light gray, scaly bark.
Leaves are stiff, obovate to narrowly obovate, elliptic, or obdeltoid, 1.6 – 7.9” long, ½ to ⅔ as wide, with rounded-attenuate, cordate, or cuneate bases. Margins shallowly to deeply lobed, uppermost two lobes at right angles in a cruciform pattern, with broadly rounded tips.
Yellowish-green lower leaf surfaces have yellowish glandular hairs and tiny semi-appressed stellate hairs, not velvety; upper surfaces are dark to yellowish green, dull or glossy, sparsely rough stellate.
Acorns in clusters of 1 – 3, subsessile or short-stalked with deeply saucer-shaped cupules sometimes constricted at the base, 0.28 – 0.7” deep, 0.28 – 1” wide, covering ¼ to ⅔ of the nut with finely gray-pubescent tightly appressed scales.
Nuts are light brown, ovoid or rounded, 0.4 – 0.8” long, nearly as wide, hairless or puberulent.
Often Confused With: Post Oak is mostly confused with White Oak, which has much larger leaves with lobes that never form a cruciform pattern and whose lower surfaces are hairless when mature; its cupules cover only ¼ of the nut and have gray tomentose scales. Sometimes it’s confused with Black Oak, which has very dark and deeply furrowed bark, usually larger leaves with lobed margins with strong awns and lower surfaces that are hairless or loosely stellate; its acorns have relatively large loose scales that form a marginal fringe.
Other Common Names: Iron Oak, Cross Oak.
Native Area: Endemic to eastern USA from eastern Kansas south through Texas, northeast through Iowa to New York, and south to Florida.
USDA Growing Zones: 5 – 9
Average Size at Maturity: 35 – 60 ft (to 100 ft) tall, 30 – 60 ft spread
17. Bur Oak – Quercus macrocarpa
The Bur Oak is a lovely large shade tree with a spreading crown, contorted branches, and deeply furrowed bark, providing both winter interest and summer shade.
It is a very cold-hardy oak growing further north and west than other white oaks, providing options for those living in colder climates where many white oaks will not grow.
It naturally grows in various conditions in open woods, sandy ridges, and alongside streams.
Best grown in full sun in acidic to alkaline, loamy, sandy, well-drained, wet, and clay soils.
It prefers moderate moisture, but once established, it has some drought tolerance.
It gets its common name from the bur-like (tuberculate) cupule on its nuts.
The nuts are sweeter than most oaks and are occasionally eaten by people.
Identifying Features of the Bur Oak
Bur Oak is a variable tree growing from a shrub to a tall tree with contorted branching.
The bark on larger specimens becomes very rough and deeply grooved.
Leaves are leathery, 6 – 12” long, oblong to obovate, with a cuneate base. Margins have 4 – 7 pairs of blunt to acute lateral lobes with a pair of sinuses near the middle that are often characteristically much deeper than the others.
Lower leaf surfaces are pale green with fine stellate hairs; upper surfaces are hairless and glossy green.
Acorns are sessile or stoutly short-peduncled, with cupules covering ⅓ to all of the nuts with loose marginal scales that are moderately to densely tuberculate, forming a terminal fringe.
Nuts are depressed or narrowly ovoid, 0.4 – 1.6” wide, and often puberulent.
Often Confused With: Bur Oak is mostly confused with White Oak, which is a taller tree with light gray, scaly bark and somewhat smaller leaves without the extra deep sinuses and with hairless lower surfaces (when mature); its cupules are not tuberculate. Sometimes it’s confused with Swamp White Oak which has a short trunk with low branches, variable bark, and leaves whose lower surfaces have small appressed-stellate hairs and velvety branched hairs, and their acorns are on long thin peduncles.
Other Common Names: Burr Oak, Mossycup Oak, Savanna Oak, Overcup Oak, Prairie Oak, and Blue Oak.
Native Area: Central North America from Saskatchewan east to Quebec in Canada and North Dakota south to Texas and northeast to Maine in the USA, with an isolated population in Alabama.
USDA Growing Zones: 3 – 9
Average Size at Maturity: 60 – 80 ft tall, 60 – 80 ft spread
Available at: Nature Hills
18. Swamp Chestnut Oak – Quercus michauxii
Swamp Chestnut Oak is another oak with more chestnut-like rather than typical oak leaves.
It grows naturally in humid temperate climates with hot summers, short, mild winters, and no defined dry season. This is not a cold-hardy tree.
Best grown in full sun in moist, well-drained, acidic sandy to silty clay loams.
It will tolerate partial shade, wet soils, and occasional flooding.
It is a highly adaptable tree that does well in urban environments, making it a lovely shade tree for a large yard or park where the acorns provide habitat and food for the wildlife.
Identifying Features of the Swamp Chestnut Oak
Swamp Chestnut Oak is a medium-sized deciduous tree with light brown or gray, scaly bark.
Leaves are broadly obovate or broadly elliptic, 2.4 – 11” long, ½ to ⅔ as wide with rounded-acuminate or broadly cuneate bases, rounded to acuminate tips, and margins that are regularly toothed with fairly large crenate or dentate teeth.
Lower leaf surfaces are light green or yellowish-white, felty to the touch with soft 1 – 4-rayed hairs; upper surface medium green, hairless, or with minute hairs.
Acorns in clusters of 1 – 3, on 1” peduncle or sometimes subsessile, with a hemispheric to short-cylindric cupule 0.6 – 1” high, 1 – 1.6” wide, covering ½ or more of the nut with gray or light brown very loosely appressed scales that are moderately to heavily tuberculate with silky-tomentose tips.
Nuts are light brown, ovoid, or cylindric, 1 – 1.4” long, about ¾ as wide, and hairless.
Often Confused With: Swamp Chestnut Oak is mostly confused with the Chestnut Oak (Quercus montana), which can quickly be differentiated by its very thick bark with very deep fissures and tall ridges, thicker than any other North American Oak, and its leaves are not so pale or felty-soft on the lower surfaces. It is also often confused with Chinkapin Oak which has nearly identical leaves, but again, the bark can differentiate the two since Chinkapin Oak has thin, sometimes papery, and somewhat exfoliating bark.
Other Common Names: Basket Oak, Cow Oak.
Native Area: Endemic to southeastern USA from east Texas northeast to southern Illinois and Indiana, east to New Jersey, and south to north-central Florida.
USDA Growing Zones: 5 – 9
Average Size at Maturity: 40 – 65 ft tall, 30 – 50 ft spread
Available at: Nature Hills
19. Gambel Oak – Quercus gambelli
Gambel Oak is a beautiful tree in more challenging cold or dry environments where it grows well down to USDA Zone 4 and is very drought-tolerant once established.
It can be grown as a multi-stemmed shrub, or by cutting off the suckers, it can be trained to grow as a small tree.
Its form naturally varies with soil quality and water availability, growing as a tree in better soil with more water or as a shrub in poor-quality dry soils.
It has great Calcium Carbonate tolerance, drought tolerance, and cold tolerance and will tolerate partial shade and fairly alkaline soils.
It requires little to no water once established.
It will not tolerate wet soils or dense plantings and is more suited to semi-arid climates with adequate drainage and ventilation.
Identifying Features of the Gambel Oak
Gambel Oak is a deciduous, often multi-stemmed clumping and spreading shrub or small to medium-sized tree with gray or brown scaly bark.
Leaves are membraneous, elliptic, obovate, or oblong, 1.6 – 6.3” long, half as wide, with truncate to cuneate bases. Margins deeply to shallowly 4 – 6-lobed, entire or coarsely toothed, sinuses acute or narrowly rounded, reaching more than halfway to the midrib, tips rounded or subacute.
Lower leaf surfaces dull green, sometimes glaucous, densely velvety with 4 – 6-rayed hairs, sometimes hairless or villous near midribs, veins prominent; upper surfaces dark green, microscopically puberulent, veins slightly raised.
Acorns solitary or paired, subsessile or 0.4 – 1.2” pedunculate, with cup-shaped cupules, 0.2 – 0.67” high, 0.28 – 1” wide, covering ¼ to ½ of the nut with gray-tomentulose closely appressed and tuberculate scales.
Nuts are light brown, ovoid to ellipsoid, 0.3 – 1.3” long, about ⅔ as wide.
Often Confused With: Gambel Oak is mostly confused with the Utah hybrid Wavyleaf Oak (Quercus x undulata), a semi-deciduous shrub with leaves with large rounded teeth (not lobes) and undulate edges. It is also sometimes confused with Valley Oak which often has deeply cross-checked bark, leaves that are smaller but relatively wider, and acorns that are always subsessile with heavily tuberculate cupules.
Other Common Names: Scrub Oak, Bush Oak, and White Oak.
Native Area: Limited range in southcentral North America, mostly in Utah, Arizona, Colorado, and New Mexico, USA, with disjunct populations in northern Chihuahua, Mexico, and west Texas, USA.
USDA Growing Zones: 4 – 8
Average Size at Maturity: 10 – 30 ft (to 60 ft) tall, 10 – 20 ft spread
20. English Oak – Quercus robur
English Oak is a very popular landscape tree widely grown in temperate climates worldwide as a specimen, shade, or street tree.
Best grown in full sun in moist, well-drained soil with lots of organic matter. It will grow in acidic to alkaline soils.
It will tolerate poor-quality soils, dry or wet soils, and partial shade but will not perform as well.
English oak contains gallotannins, quercitrin, and other compounds which can cause digestive problems if eaten and should not be planted where livestock graze.
It frequently escapes cultivation and has become naturalized in USA and Canada, but so far is not on invasive species lists.
If you do not live in its native range, I strongly encourage you to plant a native oak instead. With so many species worldwide, you should have no difficulty finding the perfect oak.
Identifying Features of the English Oak
English Oak is a medium to tall deciduous tree with a broadly rounded crown, sometimes spreading wider than it does tall.
The bark is light gray and scaly.
Leaves are obovate to narrowly elliptic (some cultivars oblanceolate), 2 – 7.9” long, and about half as wide with a strongly cordate base that is often minutely revolute. Margins are moderately to deeply lobed with rounded lobes cut ⅓ to ⅞ to the midrib.
Lower leaf surfaces are light green, hairless, or sparsely pubescent; upper surfaces are dark to light green or gray-green, dull or glossy.
Acorns in clusters of 1 – 3 on very thin peduncles 1 – 4” long with a hemispheric to deeply goblet-shaped cupule covering ¼ – ¾ of the nut with closely appressed, finely grayish tomentose scales, often in concentric rows.
Nuts are brown, ovoid to oblong, 0.6 – 1.4” long, about ⅓ as wide, and hairless.
Often Confused With: English Oak is mostly confused with Sessile Oak (Quercus petraea), but the two can quickly be differentiated by the Sessile Oaks’ much longer leaf petioles, but sessile acorns compared to English Oak’s short petioles and very long thin acorn peduncles. It is also sometimes confused with White Oak which has larger leaves with cuneate bases and narrower acorns whose cupules never cover more than ¼ of the nut and are nearly sessile or on a peduncle up to 2” long.
Other Common Names: Pedunculate Oak, French Oak, and Truffle Oak.
Native Area: ThroughoutEurope, northern Africa, and western Asia.
USDA Growing Zones: 4 – 8
Average Size at Maturity: 40 – 60 ft (to 100 ft) tall, 40 – 70 ft spread
Available at: Nature Hills
21. Garry Oak – Quercus garryana
Garry Oak is a beautiful oak native to western North America that can grow to a very large and dense mighty oak when grown in fertile soils.
It can also grow as a smaller and more contorted tree when grown in rocky, poor-quality soils.
Once established, it is drought-tolerant and should not be watered in the summer. Overwatering can make it prone to fungal diseases.
It is a large but slow-growing tree, reaching only 25 ft tall after twenty years.
Best grown in full sun in moist to dry soil of any quality. If growing in moist soils, ensure they are able to dry out in the summer.
So far, it appears to be resistant to the Sudden Oak Death that other Pacific Coast native oaks are often highly susceptible to, giving native options to those living in heavily affected areas.
Identifying Features of the Garry Oak
Garry Oak is a medium-sized single-trunked tree or multi-trunked shrub with light gray or whitish scaly bark.
Leaves are obovate, elliptic, or somewhat rounded, 1 – 5.5” long, ⅔ as wide, with often oblique rounded-attenuate, cuneate, or rarely subcordate bases. Margins moderately to deeply lobed with sinuses reaching more than halfway to the midrib; larger lobes usually with 2 – 3 lobules or large teeth.
Lower leaf surfaces light green or yellowish-glaucous, often felty-soft with simple and rayed hairs; secondary veins raised. Upper surfaces bright to dark green and glossy or somewhat scurfy with sparse stellate hairs.
Acorns in clusters of 1 – 3, subsessile, rarely short-stalked, with cupules 0.15 – 0.4” high, 0.47 – 0.87” wide, with yellowish or reddish-brown scales moderately or scarcely tuberculate, canescent or tomentulose.
Nuts are light brown, oblong to globose, 0.47 – 1.6”, ⅝ to ⅔ as wide, and puberulent or hairless.
Often Confused With: Garry Oak is often confused with English Oak which the long peduncles on its acorns can quickly differentiate it, or when not in fruit, its larger leaves with strongly cordate bases and mostly hairless lower surfaces will tell them apart. It is also confused with the Valley Oak, which often has deeply cross-checked bark, leaves that are smaller but relatively wider, and acorns with heavily tuberculate cupules.
Other Common Names: Oregon Oak and Oregon White Oak.
Native Area: Pacific Northwest of North America, mostly in the Cascade Range from coastal British Columbia, Canada, south through Washington and Oregon to south-central California, USA.
USDA Growing Zones: 7 – 9
Average Size at Maturity: 50 – 65 ft (10 to 90 ft) tall, 50 – 75 ft spread
22. Gray Oak – Quercus grisea
Gray Oaks are large shrubs or small trees with unique leathery dull blue-green to grayish leaves that sometimes turn a showy crimson red in the fall.
They are native to the American Southwest, thriving in semi-arid climates with mild winters, dry springs, and hot summers.
They are popular drought-tolerant landscape shrubs or small shade trees whose size is determined by available moisture. If you want a tree, simply provide it with irrigation in the summer months, and it will grow larger.
Otherwise, it is highly suitable for xeriscaping, where it will grow as a multi-stemmed shrub.
It can spread asexually through root suckers and may form thickets.
Best grown in full sun to partial shade in acidic to alkaline soils that are dry or moist but well-drained.
Identifying Features of the Gray Oak
Gray Oak is a large deciduous or semi-evergreen multi-stemmed shrub or small tree with contorted branches and gray fissured bark.
Leaves are thick, leathery, blue-green or grayish, oblong, elliptic, or ovate, 0.6 – 3.15” long, ⅔ – ⅞ as wide, with cordate or rounded bases and acute, obtuse, or rarely rounded tips. Margins are entire or dentate with mucronate teeth and minutely revolute.
Lower leaf surfaces dull gray-green or yellowish, minutely stellate, with very prominent secondary veins; upper surfaces dull green to gray-green, sparsely stellate with slightly raised veins.
Acorns single or paired, subsessile or on 1” peduncle with a deeply goblet- or cup-shaped cupule 0.15 – 0.4” high, 0.3 – 0.6” wide, covering to half the nut with appressed red-brown scales, lower scales slightly to noticeably tuberculate and whitish canescent to hairless.
Nuts are light brown, ovoid to ellipsoid, 0.47 – 0.7” long, ⅔ as wide.
Often Confused With: Gray Oak is mostly confused with the Scrub Live Oak, which has gray or brown scaly bark and smaller, thinner leaves that are often undulate or spinose and do not have prominent secondary veins. Sometimes it is confused with the closely related Arizona White Oak (Quercus arizonica), which has larger leaves that are greener, more oval-shaped, and generally not pointed; it also typically grows in more moist locations than the Gray Oak.
Other Common Names: Shin Oak, Scrub Oak.
Native Area: South-central North America, all disjunct, mostly mountainous populations found in southwestern USA (Texas, Arizona, New Mexico, Colorado) and south into central Mexico.
USDA Growing Zones: 6 – 8
Average Size at Maturity: 5 – 35 ft tall, 5 – 30 ft spread
23. Havard Oak – Quercus havardii
Havard Oak is a beautiful shrub oak endemic to a narrow range in the southern Great Plains of the USA.
It is a low-growing, thicket-forming shrub that spreads clonally by its rhizomes, with up to 90% of the tree’s biomass found underground.
While the above-ground portion may only live for a few decades, the shrub itself, in the form of its underground rhizomes, is hundreds or even thousands of years old.
Best grown in full sun in sandy, well-drained soils that are acidic to alkaline.
Sadly, this beautiful shrub is Endangered on the IUCN Red List, which states only 476 individuals remain in the wild.
Identifying Features of the Havard Oak
Havard Oaks are low, deciduous, clonal shrubs with light gray scaly bark, spreading via rhizomes.
Leaves are thick, stiff, oblong, elliptic, or sometimes lanceolate, oblanceolate, or ovate, 1.2 – 3.9”, ⅓ to ½ as wide with rounded to cuneate bases and rounded or rarely acute tips.
Margins are flat, revolute, or undulate, with 4 – 6 large rounded teeth or small lobes.
Lower leaf surfaces densely grayish or yellowish-tomentulose, stellate, or sparsely pubescent, with prominent secondary veins; upper surfaces very sparsely stellate or hairless, veins only slightly raised or not at all.
Acorns solitary or paired, subsessile or on 0.5” peduncle. Cupules deeply cup-shaped to goblet-shaped, 0.4 – 0.5” high, 0.6 – 1” wide, covering ⅓ to ½ the nut, sometimes with constricted bases. Scales reddish-brown with loosely appressed tips, tuberculate, pubescent, often canescent.
Nuts are brown, ovoid, 0.5 – 1” long, and 0.55 – 0.7” wide.
Often Confused With: Havard Oak is a rare species that is sometimes confused with Tucker Oak (Quercus welshii), another rhizomatous shrub oak with smaller elliptical or lanceolate leaves with 6 – 10 lobes that are densely hairy when young, then becoming mostly hairless.
Other Common Names: Shinnery Oak, Shin Oak, Harvard Oak (a misspelling)
Native Area: Narrow endemic of the southern USA in New Mexico, Oklahoma, and Texas.
USDA Growing Zones: 7 – 8
Average Size at Maturity: 3 – 7 ft (to 30 ft) tall, 5 – 30 ft spread
24. Scrub Live Oak – Quercus turbinella
Scrub Live Oak is another drought-tolerant shrub oak that thrives naturally in desert mountains but is highly adaptable and will also grow in colder or moister climates. However, it still needs a hot summer in order to thrive.
Best grown in full sun in dry to moist but well-drained sand or clay soils that are acidic to alkaline.
It is highly cold-tolerant as long as the summer is hot.
It is also highly heat and drought-tolerant and is suitable for xeriscaping once established.
It sometimes spreads clonally, forming thickets.
Identifying Features of the Scrub Live Oak
Scrub Live Oak is an evergreen or semi-evergreen shrub or occasionally small tree with light gray or brown, scaly bark.
The tree’s leaves are grayish-green, thick, leathery, elliptic, or ovate, 0.8 – 1.2” long, half as wide, with a cordate or rounded base and acute to obtuse tip. Margins are flat or slightly undulate, coarsely 3 – 5-toothed with spinose teeth, or very shallowly lobed.
Lower leaf surfaces are yellow or reddish, usually glaucous, minutely stellate-puberulent; upper surfaces are grayish, glaucous, or yellowish-glandular and hairless to sparsely stellate-puberulent.
Acorns solitary to several on peduncles 0.2 – 1.6” long with hemispheric or shallowly cup-shaped cupules 0.16 – 0.3” high, 0.3 – 0.47” wide, covering ¼ – ½ of the nut with tightly appressed and moderately tuberculate grayish or yellowish puberulent scales.
Nuts are light brown, ovoid, 0.4” long and 0.2” wide, puberulent or hairless.
Often Confused With: Scrub Live Oak is mostly confused with Muller’s Oak (Quercus cornelius-mulleri), a densely branched semi-evergreen shrub with strongly bicolored ovate, oblong or obovate leaves that are densely whitish hairy with appressed stellate hairs on the lower leaf surfaces and subsessile acorns with cupules that are strongly tuberculate near the base.
Other Common Names: Sonoran Shrub Oak, Turbinella Oak, Arizona Blue Shrub Oak, Shrub Live Oak, and Gray Oak.
Native Area: Southwestern North America from Baja California, Mexico, north to south-central California, east to southwestern Colorado, and south through Arizona and New Mexico, USA.
USDA Growing Zones: 6 – 9
Average Size at Maturity: 6 – 15 ft (to 25 ft) tall, 6 – 15 ft spread
25. Mexican White Oak – Quercus polymorpha
Mexican White Oak is a widespread native species found in Mexico and Central America with a small population in southwest Texas.
It is widely grown as an ornamental tree for its incredibly fast growth, much faster than any other white oak and faster than most trees at up to 4 ft per year if the conditions are right.
It is nearly evergreen in southern climates.
It thrives in moist soils in dry environments but is highly adaptable and grows naturally on river banks, in mountain forests, and in semi-arid desert areas.
Best grown in full sun to partial shade with medium moisture.
It is also highly resistant to oak wilt and other oak diseases and pests.
Identifying Features of the Mexican White Oak
Mexican White Oak is a medium-sized semi-evergreen tree with gray to brown, scaly bark.
Leaves are elliptic, ovate, lanceolate-ovate, or sometimes obovate, 2 – 6” long, ⅗ to ⅝ as wide, with rounded or cordate bases and rounded, acuminate, or retuse tips.
Margins are revolute, entire, or variously serrate in the upper ⅓ of the leaf.
Lower leaf surfaces are light green, sometimes glaucous, with raised veins, floccose, tomentose, or with erect golden hairs, becoming hairless; upper surfaces are dark or light green, glossy, floccose, or tomentose becoming hairless when mature, with impressed veins.
Acorns single or paired on 0.1 – 1.2” peduncles with hemispheric or funnel-shaped cupules 0.2 – 0.3” high, 0.3 – 0.8” wide, covering ½ the nut with appressed scales that are thickened basally and gray-canescent.
Nuts are light brown, hairless, ovoid-ellipsoid, 0.55 – 1” long, and about half as wide.
Often Confused With: Mexican White Oak is mostly confused with Chinkapin Oak, which has thin and papery or flaky bark, larger, wider leaves with truncate or cuneate bases, and variously toothed margins that are not toothed along the whole margin. Sometimes it’s confused with Texas Live Oak, which is more clumping in habit, has heavily contorted branches, and oblong-elliptic, narrowly ovate, lanceolate, or sometimes obovate leaves that have whitish or glaucous lower surfaces with minute white appressed stellate hairs.
Other Common Names: Monterrey Oak and Netleaf White Oak
Native Area: Throughout Mexico, Guatemala, and Honduras, plus a single population in southern Texas, USA
USDA Growing Zones: 7 – 10
Average Size at Maturity: 40 – 65 ft tall, 30 – 50 ft spread
26. Valley Oak – Quercus lobata
Valley Oak is a long-lived (to 600 years) deciduous oak endemic to California, the largest oak native to the area, growing up to 80 ft tall.
It is a lovely tree with long, drooping branches, typical oak-style leaves, and thick cross-checked bark that looks like alligator skin.
While it grows in dry Mediterranean-style climates, it prefers fertile lowlands with deep, rich soils and/or year-round access to groundwater in order to thrive.
As a landscape tree, it is best grown in moderately moist, fertile soil in full sun. It is tolerant of heat and will grow well in USDA Zones 7 – 11.
In its narrow native habitat, it is Near Threatened with a decreasing population.
Unlike most oaks, its acorns are sweet and edible, and many consider them delicious.
Identifying Features of the Valley Oak
Valley Oaks are small to large deciduous trees with gray scaly bark becoming deeply cross-checked with age.
The tree’s leaves are broadly obovate or elliptic, 1.6 – 4.7” long, ⅗ to ⅔ as wide, with rounded-attenuate, cuneate, truncate, or rarely subcordate bases, and broadly rounded tips.
Margins are moderately to deeply lobed, with sinuses cut more than halfway to the midrib with obtuse, rounded, or blunt lobes.
Lower leaf surfaces whitish or light green, densely to sparsely hairy with 8 – 10-rayed stellate hairs; upper surfaces dark green or grayish, glossy or scurfy with sparse stellate hairs.
Acorns solitary or paired, subsessile with deeply cup-shaped, hemispheric or turbinate cupules with a thick rim, 0.2 – 1.2” high, 0.5 – 1.2” wide, with grayish or cream-colored scales tuberculate toward the base.
Nuts are light brown, oblong, or ellipsoid, 1.2 – 2.4” long, and about half as wide.
Often Confused With: Valley Oak is mostly confused with the California Black Oak (Quercus kelloggii), which has irregularly furrowed bark and ovate, broadly elliptic, or obovate leaves with cordate, obtuse, or sometimes rounded bases and raised veins on both surfaces and its acorns’ cupules are only occasionally tuberculate.
Other Common Names: White Oak, Bottom Oak, Water Oak, and Roble (Spanish).
Native Area: Narrow endemic of California in the interior valleys and foothills from Siskiyou County to San Diego County.
USDA Growing Zones: 7 – 11
Average Size at Maturity: 30 – 80 ft (to 115 ft) tall, 30 – 50 ft spread
C. Section Virentes – American Southern Live Oak Species
Section Virentes contains live or evergreen oaks that are native to North America, Mexico, Cuba, and Central America.
They are trees or rhizomatous shrubs with acorns that mature in one year and, at most, are only mildly tuberculate.
A distinguishing feature of this section is their germinating seedlings have fused seed leaves (cotyledons).
Note that not all evergreen oaks are in this section. Evergreen oaks are found throughout both subgenera and most of the sections in those subgenera.
27. Southern Live Oak – Quercus virginiana
The Southern Live Oak is an iconic mighty oak tree variety native to warm southern climates where it is often draped with Spanish Moss (Tillandsia usneoides – not actually a moss but a bromeliad).
It is a very popular landscape tree where it is used as a shade or specimen tree in larger yards, parks, or other areas where it has room to grow to its eventually massive size, often spreading much wider than it grows tall.
Best grown in full sun in average, dry to moist, well-drained soils that are acidic to neutral.
It tolerates a wide range of soil moisture and will thrive on wet or dry sites, and will handle short-term flooding.
It is also tolerant of partial shade, salt, wind, and drought.
It is, however, not tolerant of cold and only thrives in USDA Zones 8 – 10.
Identifying Features of the Southern Live Oak
Southern Live Oaks are medium to large semi-evergreen trees with thick trunks, contorted branching, and dark brown or black, scaly bark.
This oak’s leaves are obovate, oblanceolate, sometimes rounded or lanceolate-ovate, 1.4 – 5.9” long, 0.8 – 3.2” wide, with cuneate, rounded, or rarely truncate or cordate bases and obtuse-rounded or acute tips. Margins minutely revolute or flat, entire or irregularly 2 – 6-toothed with mucronate teeth.
Lower leaf surfaces whitish or glaucous, with dense, minute, appressed-stellate hairs or hairless (shade leaves); upper surfaces glossy light or dark green, hairless or scattered minute-stellate.
Acorns in clusters of 1 – 3 on up to 0.8” peduncles with hemispheric or deeply goblet-shaped cupules 0.3 – 0.6” tall and wide, often with constricted bases. Scales are whitish or grayish, thick, tomentulose, with reddish tips.
Nuts are dark brown, hairless, ovoid, or cylindrical, 0.3 – 1” long, and ⅓ – ⅔ as wide.
Often Confused With: Southern Live Oak is routinely confused with the closely related Texas Live Oak, and the two often hybridize, making identification even more challenging. The main difference is that Texas Live Oaks’ acorns are spindle-shaped and narrowed at the base, and their nuts are often striated. More variable differences are that the Texas Live Oak is more often clumping in habit and typically has more extremely contorted branching.
Other Common Names: Virginia Live Oak, Bay Live Oak, Scrub Live Oak, Plateau Oak, Plateau Live Oak, Escarpment Live Oak, and Roble (Spanish).
Native Area: Southeastern North America along the Atlantic and Gulf Coasts from southern and central Texas east to Florida (including the Florida Keys) north to Virginia, USA, with disjunct populations in southwestern Oklahoma and the mountains of northeastern Mexico.
USDA Growing Zones: 8 – 10
Average Size at Maturity: 40 – 80 ft (to 115 ft) tall, 60 – 100 ft spread
Available at: Fast-Growing-Trees & Nature Hills
28. Texas Live Oak – Quercus fusiformis
Texas Live Oak, much like the Southern Live Oak, is a small to large evergreen tree with a spreading crown that typically spreads wider than it does tall, forming the “Mighty Oak” tree often described in the literature.
Because of its size, it should not be planted next to structures, foundations, overhead powerlines, etc., to ensure it has room to grow.
It is used in landscaping as a shade or specimen tree for its hardiness in dry, cold, and hot climates, performing much better in colder climates down to USDA Zone 6 than the Southern Live Oak.
Best grown in full sun in moist but well-drained soil.
Reducing summer water will make the tree healthier. They are highly drought-tolerant once established and thrive in areas with hot, dry summers.
Identifying Features of the Texas Live Oak
Texas Live Oaks are small to large evergreen or semi-evergreen trees with dark scaly bark or sometimes growing as large clonal shrubs.
This variety of oak’s leaves are oblong-elliptic, narrowly ovate, lanceolate, sometimes obovate, 1.4 – 5.9” long, ⅜ to ⅝ as wide, with rounded, truncate, cordate, or rarely cuneate bases and obtuse-rounded or acute tips.
Margins minutely revolute or flat, entire or with 2 – 6 mucronate or rarely spinose teeth.
Lower leaf surfaces whitish or glaucous, with dense, minute, appressed-stellate hairs or hairless (shade); upper surfaces glossy dark or light green, hairless or with minute stellate hairs.
Acorns 1 – 3 on 0.1 – 1.2” peduncles with funnel-shaped, hemispheric, or goblet-shaped cupules 0.3 – 0.5” high and wide, bases often constricted. Scales whitish or grayish, with reddish tips, thickened basally, tomentulose.
Nuts are dark brown, often striated, hairless, elliptical, or spindle-shaped with acute tips, 0.8 – 1.2” long, ⅜ to ½ as wide.
Often Confused With: Texas Live Oak is regularly confused with the similar Southern Live Oak. When the two hybridize, it makes identification more challenging. The main difference is the acorns of Texas Live Oak are spindle-shaped and narrowed at the base, compared to more ovoid in Southern Live Oak, whose nuts are also never striated. The Southern Live Oak tends to have less of a clumping habit, and its contorted branches are less extreme.
Other Common Names: Escarpment Live Oak, Plateau Live Oak, Plateau Oak
Native Area: Southcentral North America from southern Oklahoma south through Texas to northeastern Mexico.
USDA Growing Zones: 6 – 11
Average Size at Maturity: 20 – 50 ft (to 82 ft) tall, 25 – 40 ft (to 100 ft) spread
Some Cultivars Available:
- Joan Lionetti Texas Live Oak Quercus virginiana x fusiformis ‘Joan Lionetti’ is a heat-loving 20 – 30 ft tall tree, spreading as wide, providing dense shade with little to no maintenance. Its dark green evergreen leaves are leathery green with soft fuzzy undersides. USDA Zones 7 – 10. – Image via Fast-Growing-Trees
29. Sand Live Oak – Quercus geminata
The Sand Live Oak is a large shrub or small tree often forming thickets in sandy areas.
Their height is typically dependent on fire frequency. They resprout from their stumps and grow in clumps if burned to the ground.
They are known for their very widely spreading branches and often contorted and sinuous trunks that arch or lean on other trees.
Best grown in full sun or partial shade in moist, well-drained, acidic, loamy sand. However, it will grow well in alkaline soils, sand, or clay.
Once established, it is extremely drought-tolerant and can withstand very long periods without rain, making it very suitable for xeriscaping.
While it is highly tolerant of salt spray along the coast, its roots will not tolerate inundation with saline water.
The Vulnerable Florida Scrub-Jay is found only in scrub forests where this tree dominates.
Identifying Features of the Sand Live Oak
Sand Live Oaks are semi-evergreen multi-stemmed rhizomatous shrubs or medium-sized trees with contorted trunks, low spreading branches, and dark scaly to fissured bark.
Leaves narrowly lanceolate, elliptic, rarely rounded, convex-cupped, 0.4 – 4.7” long, ¼ to ½ as wide, with cuneate, rarely truncate or rounded bases, and acute or obtuse tips. Entire margins are strongly revolute.
Lower surfaces whitish or glaucous, with dense, minute stellate hairs and scattered felty hairs, or hairless (shade); upper surfaces dark to light green, glossy, hairless or scattered, stellate hairs, secondary veins impressed.
Acorns on this variety of oak are 1 – 3, on 0.4 – 4” peduncles with hemispheric, deeply goblet-shaped, or sometimes saucer-shaped cupules 0.3 – 0.6” high, 0.2 – 0.6” wide, often constricted bases and whitish or grayish scales thickened basally, hairless or puberulent, with reddish tips.
Nuts are dark brown, hairless, ovoid or barrel-shaped, 0.5 – 1” long, ⅓ to ½ as wide.
Often Confused With: Sand Live Oak is mostly confused with the Southern Live Oak, which is usually a larger tree with a thicker trunk and larger, wider leaves that are flat or only minutely revolute and not convex-cupped; its acorns usually have shorter peduncles and wider nuts.
Other Common Names: Sandhills Live Oak
Native Area: Endemic to southeastern USA along the Gulf and Atlantic Coasts from Mississippi east to southern Florida, and north to southeastern Virginia.
USDA Growing Zones: 7 – 9
Average Size at Maturity: 15 – 30 ft (to 80 ft) tall, 30 – 80 ft spread
D. Section Protobalanus – Intermediate Oak Species
The intermediate oaks are native to the southwestern USA and northwestern Mexico.
They are distinguished by acorns that mature in 18 months, are very bitter, and the inside surface of the shell is typically quite woolly.
There are only five species in this section, two of which are narrow island endemics.
30. Huckleberry Oak – Quercus vacciniifolia
Huckleberry Oak is a rare shrub oak endemic to the southern Pacific Northwest, mostly in northern California.
It never exceeds 5 ft in height but typically spreads twice as wide.
Its use in landscaping has increased lately for its value in restoration and revegetation projects, where it is used to prevent erosion and restore vegetation to landscapes stripped by human activities.
It also makes a great hedge or shrub for a bird or butterfly garden and will also attract bears that will eat the acorns and deer that feed on the leaves.
It grows naturally on steep slopes and ridges in coniferous and sub-alpine forests at high latitudes.
Best grown in full sun in well-drained sandy or rocky loams.
It is mildly drought-tolerant once established and is highly adapted to fire ecosystems.
Identifying Features of the Huckleberry Oak
Huckleberry Oak is a low prostrate to spreading, evergreen shrub with slender, pliable, hairless twigs.
Leaves are 0.6 – 1.6” long, brittle, elliptical to oblong, or rarely somewhat rounded, with cuneate to rounded bases, obtuse to acute tips, and margins that may be entire or sometimes mucronate-toothed.
Lower leaf surfaces are hairless; upper surfaces are hairless and dull pale green.
Acorns are 0.4 – 0.6” long, round to ovoid in shape, with a variable cupule that covers ¼ to ¾ of the nut, depending on whether the nut is ovoid (covers less) or round (covers more). They mature in 18 months and have a very bitter taste.
Often Confused With: Huckleberry Oak is mostly confused with the Canyon Live Oak (Quercus chrysolepis), which are larger shrubs with often larger oblong leaves with entire to spinulose-dentate margins, lower leaf surfaces that are often glaucous with glandular and rayed hairs, and upper surfaces that are slightly pubescent.
Other Common Names: N/A
Native Area: Endemic to the western USA in the Sierra Nevadas of California and Nevada, and the Klamath Mountains and southern Cascade Range north to southern Oregon.
USDA Growing Zones: 5 – 9
Average Size at Maturity: 1 – 5 ft tall, 2 – 10 ft spread
Subgenus Cerris – Old World or Mid-Latitude Clade – Native to Eurasia
Subgenus Cerris contains about 140 species in three sections that are all native to Eurasia and northern Africa, with about 100 species being native to China.
The subgenera are determined largely by modern molecular phylogenetic evidence and pollen characteristics requiring strong magnification.
However, their distribution helps easily set them apart since this subgenus contains almost all of the Eurasian and African species and contains none of the American species.
E. Section Cerris
Section Cerris species are native to Europe, northern Africa, and Asia.
This tree type are characterized by shoot buds surrounded by soft bristles, bristle-tipped leaf lobes, and acorns that are very bitter, mature in about 18 months, and have hairless or slightly hairy inner shells.
31. Sawtooth Oak – Quercus acutissima
Sawtooth Oak is a popular landscaping tree widely used around the temperate world.
Best grown in full sun in acidic, loamy, moist, sandy, well-drained soils, but it will also grow in heavy clay.
Once established, irrigation is usually unnecessary as it has some drought tolerance.
It transplants easily and grows at a medium to fast rate of 13 – 24” per year.
This oak’s leaves emerge yellow in the spring, turn glossy green for summer, then turn yellow or golden in the fall.
Unfortunately, this beautiful tree has frequently escaped cultivation outside its native range.
It has been introduced in parts of eastern North America and is considered invasive in some areas.
If you live in North America, please plant one of our many lovely native oaks instead. The Chinkapin and Chestnut Oaks are native and have similar leaves.
Identifying Features of Sawtooth Oak
The Sawtooth Oak is a small to moderately large tree with a pyramidal form becoming broadly rounded as it matures with thick, furrowed dark brown bark.
Leaves are thin, papery (chartaceous), oblong to oblong-lanceolate, 2.75 – 7.5” long, about half as wide, with an oblique obtuse or cordate base and an acuminate or caudate tip.
Leaf margins are strongly serrate with teeth tipped with curved or straight spiny awns.
Leaf surfaces are pubescent when young, becoming hairless; lower surfaces are yellowish with prominent secondary veins, and upper surfaces are dull to somewhat shiny olive-green.
Acorns are single or sometimes paired, sessile, ovoid, 1 – 1.4” long, 1.4 – 2” wide, with cupules covering ⅕ to ½ of the nut. Lower scales are triangular and appressed; upper scales are very tuberculate.
Nuts are brown, ovoid, or tubuliform, 0.8 – 1” long, about ⅔ as wide, with conical to truncate tips.
Often Confused With: Sawtooth Oak is often confused with Chinkapin Oak, which has thin and flaky or papery bark and thicker leathery leaves with truncate to cuneate bases and lower surfaces with appressed stellate hairs. It is also confused with the Dwarf Chestnut (Castanea pumila), which has densely hairy lower leaf surfaces, and its fruit does not look like an acorn; it has a two-valved cupule with short spines and shorter and broader nuts.
Other Common Names: ツルバミ, 橡, ツルバ
Native Area: China, Tibet, Korea, Japan, Vietnam, Thailand, Myanmar, Cambodia, Nepal, Bhutan, northeastern India.
USDA Growing Zones: 5 – 9
Average Size at Maturity: 30 – 60 ft (to 85 ft) tall, 40 – 60 ft spread
Available at: Fast-Growing-Trees & Nature Hills
32. Turkey Oak – Quercus cerris
Turkey Oak is a medium-sized tree with a broad crown and dark green rounded-lobed leaves that remain on the tree until late into fall and make a lovely shade tree.
Its rounded leaves often have people referring to it as one of the white oaks, but it is only distantly related to the white oak.
It is a highly adaptable tree, tolerating any soil type except wet soil.
Best grown in full sun in deep, fertile, well-drained soil. It will tolerate partial shade, salt (but not maritime exposure), strong winds, and drought.
It is not often grown commercially but has the potential to become invasive due to its adaptability and tolerance, which can allow it to escape cultivation.
It has been introduced in New York and Massachusetts, USA, but is not yet considered invasive in North America, although it is invasive in Ireland.
Identifying Features of the Turkey Oak
Turkey Oak is a medium to large deciduous oak with a conical crown that becomes broadly pyramidal with age, where it may spread as wide as it does tall.
The bark is dark gray and very thick and becomes deeply furrowed and splits into thick plates as it matures.
Leaves are dark green, oblong-lanceolate, 3 – 5” long, and have 3 – 8 pairs of lobes on each side that may be entire or toothed.
Acorns mature in 18 months, are up to 1” long with cupules that cover about ½ of the acorn, and are heavily tuberculate.
Often Confused With: Turkey Oak is mostly confused with English Oak, which has light gray, scaly bark, larger obovate to narrowly elliptic leaves with strongly cordate bases, and acorns with cupules that are not tuberculate. It is also confused with White Oak, which has light gray, scaly bark, larger obovate to narrowly elliptic leaves, and acorns whose cupules are also not tuberculate.
Other Common Names: European Turkey Oak and Austrian Oak.
Native Area: Throughout south-eastern Europe and Asia Minor.
USDA Growing Zones: 5 – 9
Average Size at Maturity: 40 – 60 ft (to 100 ft) tall, 35 – 60 ft spread
F. Section Ilex
Section Ilex contains about 40 species that are native to Eurasia and northern Africa.
This is a sister group to section Cerris and is sometimes included there by some authors.
It is distinguished by microscopic pollen features and acorns that mature in 12 – 24 months and are hairy on the inside.
The name Ilex is in reference to its evergreen leaves that are toothed and tipped with spines or bristly awns, looking very much like holly leaves (Ilex spp).
33. Holly Oak – Quercus ilex
Holly Oak has evergreen leaves that very much resemble the spine-tipped leaves of holly.
It’s popular in landscaping, pruned as a hedge, or grown as a shade or specimen tree for yards or parks.
They are also popular in truffle orchards since the mushrooms grow in an ectomycorrhizal association with their roots.
Best grown in full sun or partial shade in rich, moist, well-drained loams.
It has medium water requirements and is mildly drought-tolerant once established.
High levels of seed germination, along with climate change, have caused concern for their invasive potential in Britain and North America.
In North America, it is naturalized in California, but it is reported to also occur north along the Pacific Coast.
While not yet on invasive species lists, it is likely only a matter of time.
If you don’t live in the Mediterranean, grow one of your many lovely native oaks instead!
Identifying Features of the Holly Oak
Holly Oak is a medium to large-sized tree with a rounded crown with ascending and low-branching that extends down to near ground level.
The gray bark becomes fissured with age.
Leaves are evergreen, dark green, often glossy, leathery, ovate, usually 3” long (2 – 5”) by about 1” wide. Margins are often very spinose when young, resembling holly, but become more smooth and entire or nearly entire when they mature.
Acorns are about 1.5” long and typically ripen in late September or early October. The cupule is rough and scaly, not tuberculate, and covers ⅓ to ½ of the nut.
The nut is oblong, about 1” long, and has a conspicuous mucronate tip; the seed inside is very bitter.
Often Confused With: Holly Oak is often confused with the very closely related Holm Oak that is sometimes considered a subspecies of it. The two can be differentiated by the Holm Oak having ovate leaves that are usually glossy dark green instead of often round and duller and or lighter green; the Holm Oak also has sweet-tasting nuts, while the Holly Oak nuts are very bitter.
Other Common Names: Evergreen Oak and Holm Oak
Native Area: Mostly northern Mediterranean from Greece to the Iberian Peninsula
USDA Growing Zones: 7 – 10
Average Size at Maturity: 40 – 70 ft tall, 40 – 70 ft spread
34. Holm Oak – Quercus rotundifolia
Holm Oak is another evergreen oak of the Mediterranean region. It gets its scientific name Q. rotundifolia from the often nearly round leaves it has, unusual for an oak.
It produces sweet-astringent acorns that are used as a food source for livestock.
Humans have used their acorns for food since at least the Neolithic era, around 7000 BCE.
Some botanists consider it a subspecies of Quercus ilex, but plant authorities have determined it is its own species.
Though native to the Mediterranean, it does not typically grow in moist oceanic climates, preferring regions slightly inland with hot, dry summers and wet winters.
Best grown in full sun in any soil type providing it is well-drained.
Being so closely related to the somewhat invasive Holly Oak, there are concerns that this could also become invasive outside its native habitat.
Identifying Features of the Holm Oak
Holm Oak is a small to medium-sized tree, never growing more than 50 ft tall, with a large, dense, rounded canopy.
Leaves are evergreen, leathery, and medium to dark green, usually dull, nearly round, elliptical, or lanceolate with spinose to dentate margins when young but becoming nearly entire or entire as the tree matures.
Lower leaf surfaces are glaucous and densely pubescent.
Acorns mature in the fall and have semi-hemispheric cupules with rough scales that are not tuberculate.
Nuts are brown to dark brown, roughly oblong, about 1” long, with a conspicuous mucronate tip.
Often Confused With: Holm Oak is often confused with the very closely related Holly Oak and is sometimes considered a subspecies of it. The two can be differentiated by the Holm Oak having ovate leaves that are usually glossy dark green and never round, and its similar-looking acorns are very bitter to taste and not edible to humans.
Other Common Names: Sweet Acorn Oak, Ballota Oak, Sweet Oak, and Iberian Oak.
Native Area: Southern Europe on the Iberian Peninsula, France, Morocco, and the Balearic Islands.
USDA Growing Zones: 7 – 10
Average Size at Maturity: 25 – 50 ft tall, 20 – 40 ft spread
G. Section Cyclobalanopsis – Ring-Cupped Oaks
Section Cyclobalanopsis is a large section with about 90 species native to tropical and subtropical Asia and the southern Himalayas.
They are distinguished by their acorn’s cupules that have distinct rings formed from thin membranes (lamellae) not seen in any of the other sections.
Their leaves are also evergreen.
35. Japanese Evergreen Oak – Quercus acuta
Japanese Evergreen Oak is a small, slow-growing evergreen tree with a unique umbrella-like crown of glossy green evergreen leaves.
Its unique form and its compact size make it a popular specimen or shade tree for a yard or park.
Best grown in full sun in fertile, well-drained, acidic to neutral loamy or clay soils.
It prefers moist soils and tolerates heavy clay soils.
It is drought-tolerant once established.
It can tolerate strong winds but does not do well in maritime exposure.
Identifying Features of the Japanese Evergreen Oak
Japanese Evergreen Oak is a small tree with low, spreading branches creating an oval to rounded crown that sometimes has lowermost branches that descend strongly, creating an umbrella-like crown.
It mostly grows as a multi-trunked tree, but single-trunk specimens are also seen.
The bark is smooth and gray.
Leaves are dark green, glossy, 2.5 – 5” long, with cuneate bases, long-acuminate to somewhat caudate tips, and entire but often slightly undulate margins.
Lower leaf surfaces are paler yellow-green.
Acorns are brown with cupules with appressed scales and 6 – 7 conspicuous concentric rings. Cupules cover ⅓ – ¾ of the nut.
Nuts are brown, oblong, ellipsoid to somewhat rounded, with a conspicuous mucronate tip.
Often Confused With: Japanese Evergreen Oak is mostly confused with the Ring-Cupped Oak (Quercus glauca), which often has larger leaves that are sometimes serrated in the upper half and are whitish pubescent on the lower surface, and their cupules have 5 – 6 annular rings.
Other Common Names: Akagashi (赤樫 – あかがし), oogashi (大樫 – オオガシ), and oobagashi (大葉樫 – オオバガシ) in Japanese
Native Area: Japan, South Korea, Taiwan, and China’s Guizhou and Guangdong provinces
USDA Growing Zones: 6 – 9
Average Size at Maturity: 20 – 30 ft tall, 15 – 20 ft spread
36. Chinese Evergreen Oak – Quercus myrsinaefolia
Chinese Evergreen Oak is a small to medium-sized tree with an upright, rounded crown that does not spread as wide as it does tall.
Its medium-fast growth rate and its compact size make it an excellent yard or street tree.
It can even be grown in a large container on a patio, though some pruning may be necessary to maintain its shape.
Best grown in full sun to partial shade with medium moisture in sandy or clay soils.
Its scientific name is mostly misspelled in the Quercus myrsinifolia form, but that is a synonym of Quercus myrsinaefolia, its true scientific name.
Identifying Features of the Chinese Evergreen Oak
Chinese Evergreen Oak is a small to medium (rarely large)-sized tree with somewhat thick dark gray bark that becomes scaly when mature.
Leaves are papery (chartaceous), lanceolate or lanceolate-oblong, usually falcate, 2.4 – 7.1” long, about ⅓ as wide, with a usually oblique cuneate base and cuspidate or caudate tips.
Margins are serrate in the upper ⅓ of the leaf. Surfaces are hairless, and the midrib is prominent on the lower surface and slightly depressed on the upper.
Acorns are sessile, obovoid or ovoid, on erect infructescences 0.8 – 2.75” long with 2 – 3 acorns per infructescence. Cupules are 0.4 – 0.6” long and wide, obconical, covering about ½ the nut with pubescent grayish scales and have 7 – 9 rings around the cup.
Nuts are conical, 0.8 – 1” long and wide, often with a conspicuous mucronate tip, and are sparsely silky-hairy, becoming hairless.
Often Confused With: Chinese Evergreen Oak is mostly confused with the Ring-Cupped Oak (Quercus glauca), with leaves with whitish pubescence on the lower surface and acorn cupules with 5 – 6 annular rings.
Other Common Names: Bamboo Leaf Oak, Chinese Ring-Cupped Oak, 小叶青冈 (Chinese), xiǎo yè qīng gāng (pinyin), 白樫 shirakashi (Japanese).
Native Area: East central and southeast China, Japan, Korea, Laos, northern Thailand, and Vietnam.
USDA Growing Zones: 7 – 9
Average Size at Maturity: 20 – 40 ft (rarely to 100 ft) tall, 15 – 30 ft spread
Oak Tree Identification (With Photos)
Identifying Oak Trees by Their Leaf Arrangement
Oak trees have alternate spirally arranged leaves.
Their leaves are arranged one leaf per node and alternately arranged, like a regular alternate leaf, but not on opposite sides of the branch. Instead, each attached leaf is rotated slightly from the leaf below it so that they spiral around the branch.
This will help differentiate them from other trees with opposite or alternate distichous (alternate on opposite sides of the branch) arrangements.
Identifying Oak Trees by Their Lobed Leaves
Oak tree leaves actually have a lot of variability which can aid in oak leaf identification.
Yes, many are lobed like a ‘typical’ oak, but the lobes vary enormously in number, size, and shape, as well as the depth the lobes cut to the midrib and the patterns that their lobes or sinuses (the divisions between the lobes) may make.
Lobes, like leaves, are further defined by their margins and whether they are sharp or rounded or if they are entire or toothed, and if they have awns (see Identifying Oak Trees by Their Leaf Margins below).
Some teeth become so large they are referred to as lobules (small lobes).
The difference between a lobe and a lobule is that a lobule is an extension of a lobe rather than an extension from the leaf itself.
The distinction between a large tooth and a lobule follows a 25% rule. If the distance it cuts is more than ¼ of the way to the midvein, it’s a lobule. If it cuts less than ¼ of the distance, then it’s a large tooth.
Oak Identification by Their Leaf Shape
Leaves all have a general shape to them, which can be a great identification tool, including when aiming to identify oak trees.
With lobed leaves, it can be harder to recognize because you need to look past the lobes at the overall outline. If it helps, draw an imaginary line around the leaf, connecting all its tips like a dot-to-dot picture. That will give you the outline of the leaf.
Many oak trees do not even have lobed leaves. Their shape is much easier to see.
The shapes of oak leaves, lobed or otherwise, can be:
- Ovate – egg-shaped, widest at the bottom.
- Obovate – like ovate but widest at the tip.
- Lanceolate – lance-shaped, like ovate and widest at the base, but narrower, with a length-to-width ratio of 3:1 or greater.
- Oblanceolate – like lanceolate but widest at the tip.
- Oblong – with elongated, parallel sides.
- Elliptic – widest in the middle and narrowing towards both ends.
- Round (also called orbicular) or nearly round (also called suborbicular)
- Rhombic – four-sided and diamond-shaped with the petiole attaching at one corner.
- Falcate – asymmetrically curved to one side.
Additional shapes that oak leaves can be include:
- Obdeltoid – triangular but with the petiole connecting to a tip instead of the base.
- Obtrullate – the reverse of trullate, which is rhombic but with an extended tip, resembling a trowel. Obtrullate is like trullate, but where it is extended at the base instead.
- Spatulate – similar to oblanceolate but with a conspicuously narrowed, attenuate base resembling a spoon.
- Linear – long and very narrow with parallel or apparently parallel sides.
Some of the shapes are also used to describe the shape of the lobes on lobed leaves.
Some of these same terms are also used to describe the shape of the fruits.
Identifying Oak Trees by Their Leaf Tips (Apex)
The shape of the leaf and lobe tips can be useful tools in identifying the different types of oak trees.
In fact, the major red and white oak groups are often differentiated, sometimes inaccurately, by having either rounded (usually on white oaks) or pointy (usually on red oaks) lobes.
Oak leaf and lobe tips can be described as:
- Rounded – with no defined edges.
- Acute – the two sides are straight and meet at an angle less than 90°.
- Obtuse – the two sides meet at an angle greater than 90°.
- Acuminate – the sides narrow to a long, drawn-out point.
- Caudate – tapers like acuminate but with an extended tail-like appendage.
- Cuspidate – the leaf tip is mostly round but forms a very short protruding tip.
- Mucronate – leaf tip ends abruptly in a narrow, sharp point which is an extension of the midrib (sometimes called apiculate).
- Retuse – slightly indented at the tip, like emarginate, but more shallowly indented.
- Blunt – not round or angled, but in between.
Identifying Oak Trees by Their Leaf Base
Oak leaf bases also vary significantly and make another great identification tool.
Oak leaf bases can be:
- Cuneate – wedge-shaped, angled at less than 90°, sometimes called acute.
- Truncate – appears abruptly cut, truncated, as if done with scissors.
- Obtuse – angled at greater than 90°.
- Rounded – having no defined edges or angles.
- Cordate – cleft and lobed with the petiole in the indent, like the base of a heart.
- Attenuate – like narrowly cuneate but with concave margins that fold slightly inwards.
- Decurrent – where the leaf base extends down onto the petiole.
- Oblique – asymmetrical, with one side larger, longer, or differently shaped than the other. Oblique leaves are sometimes described as oblique cordate, oblique attenuate, etc.
Identifying Oak Trees by Their Leaf Margins
Oak trees have a lot of interesting margins that also vary significantly between the different types of oaks.
Of course, many oak leaf margins are variously lobed. The margins on those lobes are described the same as we would a leaf that is not lobed.
The types of leaf and lobe margins seen in oaks include:
- Entire – margins are without lobes, lobules, teeth, or other features.
- Large rounded or sharp teeth – not big enough to be lobes or lobules, but larger than normal crenate or serrate teeth.
- Crenate – smaller rounded teeth.
- Serrate – having sharp, jagged teeth that point forwards.
- Dentate – square or triangular teeth that point outwards.
- Spinose – with stiff acuminate spines along the margin.
- Mucronate–toothed – having a tiny, narrow tooth.
- Revolute – the edges are rolled under towards the back of the leaf.
- Undulate – margins that are smooth but not flat and go up and down at the edges, undulating like a wave.
Oak leaves also sometimes have awns. Awns are hair or bristle-like appendages on the tips of leaves (called an apical awn) or the tips of serrated teeth. The serrated teeth of Sawtooth Oak in the photos below have awns on the ends of its teeth.
Identifying Oak Trees by Their Leaf Texture
Since oaks come in both evergreen and deciduous, their leaf textures can vary significantly. Texture is something you must feel in order to describe accurately.
Many deciduous and some evergreen oaks have membraneous leaves that are thin and very pliable.
Some deciduous oaks have leaves that are more papery (chartaceous). Papery leaves can be thin and somewhat brittle or thicker and feel dry. They are always less pliable than membraneous leaves.
Many oaks have thicker leaves that feel more leathery.
Finally, some oaks have very stiff leaves that are not pliable at all.
Oak Identification by Their Hairs (Trichomes) and Other Surface Features
Once again, oaks do not disappoint; they have a vast array of interesting plant hairs (properly called trichomes) and other surface features that make for useful identification tools.
Plant hairs are described by their length, appearance, color, and feel.
Some of the plant hairs seen in the Quercus genus include:
- Pubescent – short, soft straight hairs.
- Puberulent – like pubescent, but the hairs are very short.
- Tomentose – curled and matted against the surface.
- Tomentulose – like tomentose but smaller, less densely packed hairs.
- Rayed – with multiple hairs branching from the same point. These can sometimes be seen with the naked eye but may require magnification to see.
- Stellate – a form of rayed hair, but where the hairs spread from the central point in a distinctive star shape.
- Silky – long straight hairs, somewhat one-directional and very soft to the touch.
- Velvety – shorter straight hairs that are very one-directional and feel velvety to the touch when rubbed the right way.
- Glandular – having glands on top of the hair.
- Floccose – short matted hairs that rub off easily, falling off in clumps.
- Canescent – very soft, very short hairs that are hard to see individually but give the surface a gray or hoary look.
- Tufts in Vein Axils – various types of hairs can also be found in tufts in the vein axils on the lower sides of leaf surfaces.
Some of the other surface features we see in oaks are glaucous coatings, especially on the lower leaf surfaces. This is an epicuticular waxy secretion that can be rubbed off and gives surfaces a blue-green, gray-green, or yellow-green appearance.
Raised secondary veins are seen in many species and can help with their identification. They may be raised on the lower and/or upper leaf surface. Or other times, the veins are impressed (sunken in) on the upper surface.
Rugose surfaces are when it appears wrinkled. It is often (but not always) caused by impressed veins.
Identifying Oak Trees by Their Inflorescences
Oaks are monoecious trees with separate male and female flowers on the same tree.
The male flowers are yellowish or yellow-green, very small, and grouped into catkins. Catkins are long, thin, spike-like inflorescences that usually pendulously from branches in spring.
Female flowers are also typically greenish or yellowish, very small, and are seldom seen since they are arranged in one to few-flowered inflorescences in the axils of leaves.
Since oak flowers are small and inconspicuous, they are not often used when learning to identify oak trees.
However, the picture below will show you what male catkins look like to help you identify a tree as an oak.
Identifying Oak Trees by Their Acorns
The fruit that oak trees produce is commonly called an acorn.
Acorns are adorable little fruits that make fantastic tools in helping identify the different types of oak trees.
Acorns, unlike so many ‘nuts’ out there, are actually true nuts in the strict botanical sense of the word.
Botanically speaking, a nut is a fruit with a woody pericarp (shell) formed from a single ovary.
Oak nuts are contained in a cup-shaped structure (a cupule) formed from flower bracts. The cupules are not derived from the ovary, so they are still a true nut, not a drupe like cherry or a pseudodrupe like that of pecan or hickory.
Acorns are described by the characteristics of their cupules and their nuts.
Cupules are made of many small scales that may be loose or tightly appressed and come in different sizes, shapes, and colors, and can be hairless or variously hairy.
Often the scales form tubercules or warty outgrowths that greatly help with identification.
Cupules are also described by their overall shape. Most are cup, bowl, or saucer-shaped. But many are also turbinate (top-shaped or obconical, like an inverted cone), funnel-shaped, conical (cone-shaped), or goblet-shaped (cup-shaped with a constriction at the base, making it look like a wine goblet).
Finally, we also describe cupules by how much of the nut they cover, with some covering ¼ of the nut or less while others cover ¾ of the nut or sometimes all of it.
The nut itself (the woody shell and the seed within) is described by its shape. We use much of the same shape terms for fruits as we do for leaves, but in three dimensions.
For example, nuts can be ovoid (like ovate, egg-shaped), ellipsoid (elliptical in three dimensions), oblong (elongated with parallel sides), round (also called globose or spherical), hemispheric (half a sphere), tubuliform (tube-shaped, also oblong, barrel-shaped), or fusiform (spindle-shaped, significantly narrowing at both ends).
Nuts are sometimes described by their tips which can be variously round, acute, or mucronate, using the same terms described above for leaf tips.
Nuts are also described by their color and whether or not they are striated, having bands of lighter and darker brown. They may also be hairless or sometimes pubescent or puberulent.
Oak Identification by Branch Growth
Most oaks tend to have spreading branches.
Spreading branches are a combination of the three main types of branching patterns, with ascending branches usually in the center and top of the tree, horizontal at the middle and sides, and lowermost branches that become descending.
Ascending branches grow directed upwards to the top of the tree.
Horizontal branches come out of the trunk at a 90-degree angle. Their tips may ascend, descend, or remain horizontal.
Descending branches come out of the trunk in a downward direction.
Many oaks are characterized by having strongly contorted branches that bend wildly in all directions. This is common in many North American oaks.
Many oaks have branches that reach near ground level, and some are characterized by having very short trunks with main branches that start very low on the trunk.
Identifying Oak Trees by Tree Habit
Tree habit is the overall shape that a tree has when viewed from a distance.
Just like with lobed leaves, you need to look past the individual branches and look at the overall outline of the tree.
When young, oak trees tend to start out pyramidal (wider at the bottom, narrow at the top, Christmas tree-like) or conical (wider at the bottom and narrower at the top, like pyramidal but more compact, bullet-shaped).
Rarely do oaks maintain those forms. Mostly, oak branches become widely spreading, creating broadly rounded crowns.
Sometimes they are more narrowly rounded (oval) or spreading but a bit irregular and called spreading or irregular depending on how irregular it is.
Cultivars may have additional forms that are columnar (short and/or ascending branches creating a narrow column-like form) or fastigiate (branches that ascend so strongly they are nearly vertical, creating a very narrow form).
Oaks may grow as single-trunked or multi-trunked trees or shrubs.
Many oaks have very thick trunks, and some trunks flare strongly at the base.
Identifying Oak Trees by Their Bark
Finally, the bark can also be a useful tool in helping identify the different types of oaks.
All bark starts out smooth when it is young. Rarely will oak trees remain smooth as they mature, though some of the smaller shrubbier forms more commonly do.
The type of bark that develops is often dependent in part on the thickness of the bark.
Very thin bark sometimes becomes papery and somewhat exfoliating as it matures (rare in oak).
Those with relatively thin bark frequently develop flaky or scaly bark as it matures. Sometimes the scales are irregular, but often, it develops regular rectangular, squarish, or rounded plates that lift at the edges slightly and may occasionally peel off.
Those with thicker bark routinely develop vertical furrows or grooves that are separated by taller ridges. We usually describe furrows as being deep or shallow and ridges as being broad or narrow.
Finally, sometimes thick bark becomes cross-checked with both vertical and horizontal furrows creating rectangular or squarish blocky ridges that sometimes look like the skin on an alligator’s back.
Mighty Oak Trees
Growing Oak Trees in Your Garden
In botany, oak trees are revered for their extensive genus, which encompasses a wide variety of species each adapted to different environmental conditions.
Mighty oaks are gorgeous shade or specimen trees for any yard large enough for them to grow.
Shrub oaks make great hedges, borders, or additions to bird and butterfly gardens, and many are suitable for xeriscaping.
Some of the oak species are known to be invasive outside their native range.
You should always try to choose species native to your area to enhance biodiversity and wildlife values and reduce the risk of invasive species. Countless native insects are entirely dependent on your native oaks for their survival.
With so many native oaks worldwide to choose from, you should have no problem choosing a suitable native one for your yard.
Climate Requirements for Oak Trees
Most oak tree varieties tend to grow well in the temperate zones of USDA Zones 5 – 8, but some will grow well in colder climates down to USDA Zone 3, and still, others are very heat-tolerant and can be grown into USDA Zone 11.
Read up on your chosen variety and ensure it is compatible with your climate.
If you are unsure which zone you are in, check out the USDA Planting Zones for more information.
Soil, Water, and Light Requirements for Oak Trees
For the most part, oaks are sun-loving trees that should be planted in full sun.
Some will tolerate partial shade, so if you have partial shade, choose your tree carefully to ensure that species will handle partial shade.
None will grow in full shade; if you have full shade, hemlock trees are a great choice as they are one of the few trees that thrive in full shade.
In general, Oaks tend to prefer moderately fertile, deep, acidic, well-drained soils.
However, many will grow well in very poor soils, rocky soils, and clay soils, and some will tolerate or even thrive in alkaline soils.
As for moisture, oaks range from being extremely drought-tolerant trees or shrubs of semi-arid desert climates to trees that grow in humid climates in swampy wet soils.
Again, read carefully about your chosen tree for its requirements.
If you want more information on choosing the right tree for the right spot, check out How to Pick A Tree For Your Yard.
Harvesting Acorns
Most acorns are very bitter and considered inedible by humans.
White Oak, Bur Oak, Valley Oak, Mexican White Oak, and Holm Oak are some notable exceptions that produce sweet, edible nuts.
If you have one of the sweet-tasting oak tree varieties, you can harvest the nuts when they turn brown and just start to fall off the tree. If their cupules do not easily detach, they are likely not quite ready to be harvested.
Simply hand-pick them from the tree or shake the branches and collect the nuts from the ground.
Allow them to dry for about a week, remove any remaining cupules still attached, and they can be stored whole in a dry location for about a year.
Pests and Diseases of Oak Trees
If your oak is thriving, it will generally remain disease-free. However, there are a couple of notable diseases that can be lethal to the trees.
Oak Wilt is the most common disease to affect oaks. It is caused by the fungus Bretziella fagacearum.
It is first observed near the top of the tree as browning and bronzing of the leaves from the veins and margins toward the petiole. After some time, the leaves drop prematurely, and eventually, the tree dies.
Healthy oaks will not succumb to the Oak Wilt even in an infected area. If your tree is planted in a suitable climate and location that meets its needs well, you should not have an issue. If you are concerned about the disease, Bur Oak and Mexican White Oak seem particularly resistant.
Sudden Oak Death is a newer disease that is devastating some North American oaks, particularly on the west coast.
It is caused by Phytophthora ramorum, an invasive protist, and is visible as bleeding cankers on the trunk followed by premature leaf drop, often killing the tree.
If you live in the Pacific Northwest of North America and want a native option, the lovely Garry Oak seems to be resistant. If you want more information about Sudden Oak Death, Oregon State University developed a terrific informative PDF.
Interesting Facts About Oak Trees
The Pechanga Great Oak is a Coastal Live Oak near Temecula, California, that might be the world’s oldest oak at around 2000 years old.
The Seven Sisters Oak in Louisburg, Louisiana, is a Southern Live Oak that is estimated to be at least 1000 years old with a 150 ft wide crown and a nearly 12 ft wide trunk.
The Major Oak in Sherwood Forest, England, is a massive English Oak that is believed to be 800 – 1000 years old. Legend has it that Robin Hood used this tree for shelter.
The mighty oak has been written about in poetry and literature throughout its range worldwide for thousands of years.
As a child growing up, I can still remember a funny poem my mom had on the wall:
“Don’t worry if your job is small,
And your rewards are few.
Remember that the mighty oak,
Was once a nut like you.”
Human Uses of Oak Trees
Oak trees are widely used in landscaping as shade, street, border, and specimen trees.
The shrub forms are used in hedges, gardens, and borders, as well as in ecological restoration to prevent soil erosion.
Some acorns are harvested and consumed by people, but only on a local scale. Holm Oak, White Oak, Bur Oak, and Valley Oak are some that varieties of oak that produce edible acorns.
Sweet acorns are often used for livestock feed.
Oak wood is very dense and popular for use in lumber, especially for furniture, boat-making, and other specialty products where strong wood is desired.
The USA used to build their warships with Southern Live Oak, and their hulls were reportedly so tough that cannonballs from the British warships would literally bounce off of it.
Oak wood chips, or oak barrels, are often used to impart a mildly smoky flavor to wines (especially red wine) and hard liquors.
Quercus suber, The Cork Oak, native to Europe and Africa, is the main source of cork used for wine bottles, cork flooring, and cricket balls.
Wildlife Values Oak Trees Provide
The mighty oak is a beautiful tree with value in its own right. However, they also bring immense wildlife and ecosystem values that are so vital to the survival of so many other species.
Oak trees are critical components of mixed forests around the temperate world, providing important structural diversity.
While humans seldom eat acorns, they are rich in protein, carbs, fats, and minerals and make an excellent food source for wild animals. Countless animals use them regularly for nutrient-dense food, including pigs, bears, deer, raccoons, wild turkeys, waterfowl, quail, squirrels, and more.
Deer and rabbits routinely graze on leaves in the summer and twigs and buds in the winter.
Birds and squirrels routinely nest in mature oak trees, and larger animals use the trees for cover.
Oak trees support more moth and butterfly species than any other native or non-native tree species, making these trees critical to the survival of our native Lepidoptera.
They are also host or habitat for countless other native insects and invertebrates that are vital to the proper functioning of forest ecosystems throughout the northern hemisphere.
Mature oaks often provide critical habitats for countless epiphytic mosses, lichens, bromeliads, and plants.
I hope you have enjoyed learning about these amazing and sometimes mighty trees. Now you can use your newfound skills to go out and identify the oaks around you or choose the perfect (hopefully native) one to plant in your yard!
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