Chestnut trees are beautiful shade trees with often fragrant flowers and interesting spiky fruits with a tasty treat inside.
True chestnuts all belong to the Castanea genus in the Fagaceae or Beech family of trees, with eight currently accepted species, all native to temperate regions of the Northern Hemisphere.
Sadly, the Chestnut Blight has devastated most North American chestnuts, but some resistant trees have been found, and breeding programs are underway to revive those iconic trees. Asian varieties that evolved with the blight are much more resistant to it.
Horse Chestnuts are from an unrelated genus, Aesculus, in the Sapindaceae family. They have spiky fruits that resemble chestnuts but are poisonous. There are 13 currently accepted species of Aesculus native to the temperate Northern Hemisphere.
Let’s learn about the different types of chestnut trees and how to identify them!
Guide to Chestnut Tree Varieties – 10 Types and Their Key Characteristics
1. American Chestnut – Castanea dentata
The American Chestnut is a tree few North Americans have seen in its full form because it was so badly devastated by the Chestnut Blight that arrived in 1904 with imported Asian chestnuts. It spread so rapidly that by the 1950s, only a handful of the original billions of trees remained.
Now, all that remains of this once dominant tree are re-sprouting stumps, aside from some isolated individuals found mostly outside of the tree’s historical range.
It is Critically Endangered and considered ‘functionally extinct’ because even though it survives from resprouting stumps, it cannot grow large enough to reproduce before the blight knocks it back.
Scientists have been developing American-Asian hybrids to try to revise the species.
American Chestnuts are tall deciduous trees with rounded, spreading crowns.
They are self-incompatible and require more than one tree for pollination.
Identifying Features of the American Chestnut
American Chestnuts were tall trees with rounded, spreading crowns, but now mostly persisting as multi-stemmed resprouting shrubs.
Twigs are hairless.
The bark is smooth and gray, becoming grooved with age.
Leaves are simple, narrowly obovate to oblanceolate, 3.5 – 11” long, and about ⅓ as wide, with a cuneate base, acute or acuminate tip, and margins that are sharply serrate with teeth that taper to a long, fine awn.
The lower leaf surface appears hairless but has embedded glands and sparse, straight hairs along veins; stellate and tufted hairs are absent. Petioles are 0.3 – 1.6” long.
Staminate flowers have whitish or yellowish hairs in the center.
Pistillate flowers have three flowers per cupule.
Fruits are 4-valved, mostly hairless but densely spiny cupules that enclose 3 obovate true nuts encased in a woody pericarp ¾ – 1” long and wide. Cupules dehiscing irregularly along four sutures when mature.
Often Confused With: The American Chestnut is mostly confused with the Chinese Chestnut, but that one has hairy twigs, hairy leaves, and spiny cupules that are also pubescent. Sometimes it is confused with the Sweet Chestnut, but that has elliptic-ovate to lanceolate leaves that are less variable in size, and its grooved bark is usually v-grooved and or spirally grooved rather than regularly grooved.
Other Common Names: American Sweet Chestnut
Native Area: Eastern North America from Mississippi east to Georgia, USA, and north to Ontario, Canada, and Maine, USA.
USDA Growing Zones: 4 – 8
Average Size at Maturity: 50 – 75 ft (to 100 ft) tall, 50 – 75 ft spread**
**These are pre-blight sizes – now resprouting stumps reaching a maximum height of 30 ft.
2. Chinese Chestnut – Castanea mollissima
Chinese Chestnuts are medium-sized trees that usually only grow to about 40 ft tall, making them suitable for the home garden, orchards, or as a street or shade tree.
They produce sweet, edible, and delicious nuts that are often harvested for human consumption but are also important food for wildlife, including deer, small mammals, and birds.
They also produce their edible crops very early, just four years after planting, twenty years earlier than the American Chestnut.
In the fall, its dark green leaves turn yellow or yellow-brown.
Best grown in full sun in medium to wet, well-drained loamy soils that are fairly acidic in the 4.5 – 6.5 pH range.
Once established, they are low-maintenance trees that are moderately resistant to the Chestnut Blight.
Outside their native habitat, they have shown little invasive potential.
Identifying Features of the Chinese Chestnut
Chinese Chestnuts are medium-sized trees with low branches and an open, rounded crown.
The bark is gray and becomes irregularly grooved when mature.
Twigs are puberulent to pubescent, sometimes with pilose hairs.
Leaves are dark green, elliptic-oblong to oblong-lanceolate, 4 – 8” long, with rounded to truncate bases, acute to acuminate tips, and coarsely serrated margins.
Lower leaf surfaces are tomentose to pubescent along veins and may be pubescent on the surface; the upper surface may or may not have scale-like glands. Petioles are 0.4 – 0.8” long.
Aromatic creamy yellowish flowers appear in catkins, with male flowers at the top of the catkin and female flowers in cupules at the base.
The fruit has 2 – 3 roughly 1” wide nuts per cupule.
Cupules are densely covered with pubescent spiny bracts.
Often Confused With: Chinese Chestnut is mostly confused with the American Chestnut, but that one has hairless twigs, mostly hairless leaves, and the spines on its cupules are also hairless. Sometimes it is confused with Sweet Chestnut, which has tomentose young twigs, leaf bases that are often oblique, and lower leaf surfaces that are pale green and puberulent.
Other Common Names: 板栗 (Chinese), bǎnlì (Pinyin)
Native Area: China, Taiwan, Korea.
USDA Growing Zones: 4 – 8
Average Size at Maturity: 30 – 40 ft (to 60 ft) tall, 30 – 40 ft (to 60 ft) spread
3. Hybrid Chestnut Tree – Castanea dentata x mollissima
The Hybrid or Dunstan Chestnut is the result of hybridizing an American Chestnut discovered in Ohio in a grove of otherwise dead chestnut trees with the more resistant Chinese Chestnut to create the best blight-resistant chestnut currently available.
They are beautiful ornamental trees for any home garden or landscape, with lush green leaves that turn yellow in the fall.
They also produce abundant annual crops of large, sweet nuts that are easy to peel and are never bland or bitter.
They start to produce nuts only three years after planting, a trait they received from their Chinese parent.
Best grown in full sun in well-drained soil with medium moisture.
They do not like soggy roots, so it is recommended to mulch heavily around the roots to reduce watering frequency, and it will also protect them from both heat and cold.
Identifying Features of the Hybrid Dunstan Chestnut
The Hybrid Dunstan Chestnut is a medium-sized tree with leaf and flower characteristics that are a mix of both the American and Chinese Chestnut.
The bark is gray and grooved when mature.
Leaves are simple, roughly elliptical, with serrated margins that are not as coarse or sharp as either parent.
Flowers are in showy inflorescences of creamy white flowers.
Fruits are spiny cupules with 2 – 4 nuts within.
Often Confused With: The Hybrid Chestnut can usually be differentiated from its American Chestnut parent by its less sharply serrated teeth that do not taper to such a fine point. It can usually be differentiated from its Chinese Chestnut parent by its cupules that are not nearly as pubescent. Being a hybrid, however, means that the traits can vary. If you see variable traits on a spectrum between two parent species, that is usually a great clue that you are looking at a hybrid.
Other Common Names: Dunstan Chestnut
Native Area: N/A
USDA Growing Zones: 5 – 8
Average Size at Maturity: 40 – 60 ft tall, 30 – 40 ft spread
4. European Chestnut – Castanea sativa
The European Chestnut is often called the Sweet Chestnut.
It is a large tree with a straight trunk and branches that emerge low on its often very broad trunk.
It is a long-lived tree, easily surviving 500 – 600 years. The oldest known living tree is somewhere between 2000 – 4000 years old and is found on the eastern slope of the Mt Etna volcano in Sicily.
They produce huge crops of delicious edible nuts with two nuts per fruit.
They are easy-to-grow trees that grow in most soil types, including poor soils, but they prefer mildly acidic to neutral, well-drained soils.
Best grown in full sun.
It shows little invasive potential outside of its native habitat.
Identifying Features of the European Chestnut
European Chestnuts are tall trees with straight trunks with branches that emerge low on their trunks.
It has gray bark that becomes grooved as it matures, where the grooves sometimes interlace each other, creating V or diamond-shaped grooves but also tend to run spirally up the trunk rather than straight up and down.
Young twigs are tomentose.
Leaves are elliptic to ovate-lanceolate, 5.5 – 8.9” long, and about ⅓ as wide, with prominent lateral veins on the lower surface that end at the coarsely serrated marginal teeth with small awns. The tip is acuminate, and the base is often oblique.
Leaves are leathery green and hairless above and pale green puberulent below.
Inflorescences are 5.5 – 7.5” long and are pubescent. Female flowers are solitary or in clusters of three at the base of the male catkin.
Fruit is a densely spiny cupule encasing 2 – 3 nuts.
Often Confused With: The European Chestnut is often confused with the American Chestnut, which has hairless twigs, narrowly obovate to oblanceolate leaves with well-developed awns, and fruits with 3 nuts per cupule. It is also sometimes confused with the Chinese Chestnut, which has shorter elliptic-oblong to oblong-lanceolate leaves with rounded to truncate bases, and bark that is irregularly grooved rather than v-grooved or spirally grooved.
Other Common Names: Sweet Chestnut, Portuguese Chestnut, Italian Chestnut, Spanish Chestnut, Marron (French)
Native Area: Southern Europe, Asia Minor.
USDA Growing Zones: 5 – 7
Average Size at Maturity: 65 – 100 ft tall, 30 – 50 ft spread
Some Cultivars Available:
5. Japanese Chestnut – Castanea crenata
Japanese Chestnut trees are medium-sized trees that are resistant to the Chestnut Blight and are also being used to develop disease-resistant hybrids of the American Chestnut.
They are sometimes grown for the large nuts with pointed tips they produce that are edible, and depending on who you ask, they are either bitter or sweet and delicious.
They are more often grown ornamentally and make a lovely shade, border, or specimen tree.
Easy to grow, they are adaptable to any soil type, including poor, but they prefer well-drained loams that are mildly acidic to neutral, although they will also grow well in very acidic soils.
They can be grown in partial shade or full sun.
Fortunately, this tree also shows little invasive potential outside its natural habitat.
Identifying Features of the Japanese Chestnut
Japanese Chestnut is a medium-sized tree with low branching and an open, rounded crown.
Leaves are oblong-lanceolate, 3.2 – 7.5” long, with a broadly cuneate, rounded, or rarely almost cordate base and an acuminate to acute tip. Petioles are 0.2 – 1” long.
Leaf margins are finely serrated with leaf veins ending at the teeth that often narrow to fine bristly awns. Lower surfaces are tomentose with brown to yellow-gray scaly glands.
Male inflorescences are 2.75 – 7.9” long. Female flowers have three per cupule.
Fruits are a 2 – 2.5” wide cupule with spiny bracts about ½” long and 2 – 3(4) nuts per cupule that are about 1” wide and whose tip is sparsely appressed-pubescent.
Often Confused With: The Japanese Chestnut is mostly confused with the European Chestnut, which has longer elliptic to ovate-lanceolate leaves that are pale green and puberulent on the lower surface and often have oblique bases.
Other Common Names: Korean Castanea, Korean Chestnut, Kuri
Native Area: Japan, South Korea
USDA Growing Zones: 4 – 8
Average Size at Maturity: 35 – 50 ft tall, 30 – 40 ft spread
6. Dwarf Chestnut – Castanea pumila
Dwarf Chestnut trees are native to the southeastern USA and grow up to 30 ft tall but sometimes also remain as large shrubs.
It has dull to glossy green leaves that turn yellow to golden brown in the fall.
Creamy-white flowers appear in catkins in spring.
They produce edible nuts that are sweet to bland but are loved by wildlife, including squirrels, chipmunks, birds, and opossums. Deer enjoy feeding on the leaves.
Best grown in full sun in dry, sandy loam. It does not like wet soil, and once established, these trees can tolerate hot, dry summers.
This tree is somewhat resistant to the Chestnut Blight and often recovers if infected.
Identifying Features of the Dwarf Chestnut
Dwarf Chestnut is a large shrub to small tree with gray to brown bark that may be smooth to lightly grooved.
Twigs are puberulent with spreading hairs but occasionally become hairless with age.
Leaves are on short petioles 0.1 – 0.3” long. They are narrowly elliptic, narrowly obovate, or oblanceolate, 1.6 – 8.3” long, and ½ to ⅓ as wide, with a rounded to cordate base.
Leaf margins are obscurely to sharply serrated with a very small awn. Lower surfaces are densely hairy with appressed stellate or villous whitish to brownish hairs or sometimes hairless on shady leaves. Veins are typically puberulent.
Female flowers are only one per cupule.
Fruits are 1.5” wide with a 2-valved cupule with short spines, usually less than 0.4” long, and have one nut per cupule. Nuts are ovoid-conical and 0.3 – 0.8” long and about as wide.
Often Confused With: Dwarf Chestnut is often confused with the American Chestnut, but that one has hairless twigs, grooved bark, and usually larger leaves on much longer petioles; its fruit also has 4-valved cupules with three nuts instead of one.
Other Common Names: Alleghany Chinkapin, Chinquapin, American Chinquapin, Common Chinquapin, Ozark Chinkapin
Native Area: Endemic to the southeastern USA from New Jersey west to Ohio, south to Florida, west to eastern Texas, and Oklahoma.
USDA Growing Zones: 4 – 9
Average Size at Maturity: 15 – 30 ft tall, 10 – 20 ft spread
7. Ozark Chinkapin – Castanea ozarkensis
The Ozark Chinkapin is a rare chestnut endemic to the Ozark-Ouachita Mountains in the southeastern USA.
It grows naturally in full sun on rocky, dry soils on mountain slopes with rapid drainage. It doesn’t tolerate standing water.
You can start them by seed, but they must be stratified in the fridge in coconut coir or peat moss for them to germinate. They are best planted where they are meant to grow so that you avoid damaging the sensitive taproot.
They are drought-tolerant trees that should not be watered often and should not be planted anywhere the water stands after heavy rains. Also, avoid mulching, which may encourage their sensitive taproot to rot.
It’s sometimes called Castanea pumila var. ozarkensis, but plant authorities consider that a synonym.
It is not resistant to blight, but the Ozark Chinquapin Foundation discovered some resistant trees and is breeding them now.
Identifying Features of the Ozark Chinkapin
The Ozark Chinkapin is a tree or shrub that used to grow to 65 ft tall but now rarely exceeds 30 ft, mostly growing as multi-stemmed resprouts following blight.
The bark is brownish and slightly to deeply grooved.
Twigs are hairless.
Leaves are narrowly obovate or oblanceolate, usually 4.7 – 7.9” long but can vary, are ⅓ – ¼ as wide, and have about ½” petioles. Bases are rounded, somewhat cordate, or slightly cuneate; tips are acute or acuminate.
Leaf margins are sharply serrated with a long awn. Lower surfaces are densely to sparsely covered with appressed, whitish, minute, stellate hairs but maybe mostly hairless on shaded leaves.
There is one female flower per cupule.
Fruits are a 2-valved cupule with spines typically greater than 0.4” long and enclosing a single nut. Nuts are ovoid-conical, ⅓ – ¾” long, and almost as wide.
Often Confused With: The Ozark Chinkapin is a rare tree that is mostly confused with the Dwarf Chestnut, which has puberulent twigs, smoother bark, shorter petioles, shorter awns on the serrated teeth on its leaves, and shorter spines on its cupules.
Other Common Names: Ozark Chinquapin
Native Area: Narrow endemic of the Ozark-Ouachita Mountain regions of Missouri, Arkansas, Louisiana, Mississippi, and Oklahoma. It may have been native to Alabama but has been extirpated (locally extinct).
USDA Growing Zones: 5 – 9
Average Size at Maturity: 40 – 60 ft tall, 30 – 40 ft spread
8. Seguin’s Chestnut – Castanea seguinii
Seguin Chestnut is a small tree or shrub that is occasionally cultivated as an ornamental or for its small edible nuts.
It grows naturally in forests and thickets at moderate to high elevations in southern China, providing important food for the local people and animals.
Golden Snub‑Nosed Monkeys eat the bark as a winter food source.
In China, it is often planted as a hedge around the Chinese Chestnut orchards as a trap crop for the gall wasps Dryocosmus kuriphilus. The wasps attack the less valuable Seguin Chestnut, and the galled twigs are cut off and destroyed, allowing the more valuable Chinese Chestnut to produce bigger crops.
Identifying Features of the Seguin’s Chestnut
Seguin’s Chestnut is a small tree or shrub.
Leaves are oblong‑obovate or elliptic‑oblong, 2.4 – 5.5” long, with rounded or sometimes almost cordate bases that are cuneate when young and have acuminate tips.
Leaf margins are coarsely serrated, and lower surfaces are covered with yellowish-brown or gray scaly glands and have sparse hairs along the veins when young.
Petioles are 0.2 – 0.5” long, and there are narrowly lanceolate stipules at their base that are nearly as long as the petioles but are shed when the plant is in fruit.
Catkins are 2 – 4.7” long with 1 – 3 female flowers in cupules at their base.
Cupules are 1.2 – 2” wide and covered with sparsely pilose spiny bracts 0.2 – 0.4” long. Each cupule contains 1 – 3 nuts that are 0.5 – 0.8” wide.
Often Confused With: Seguin’s Chestnut is sometimes confused with the Chinese Chestnut, which is a larger tree with longer elliptic-oblong to oblong-lanceolate leaves with much longer petioles and larger nuts encased in a cupule with densely pubescent spiny bracts.
Other Common Names: Dwarf Asian Chestnut, Chinese Dwarf Chestnut, Chinese Chinquapin
Native Area: Endemic to southern China.
USDA Growing Zones: 5 – 9
Average Size at Maturity: 30 – 40 ft (to 60 ft) tall, 30 – 40 ft spread
9. Horse Chestnut – Aesculus hippocastanum
Horse Chestnut gets its common name from its chestnut-like spiny fruits. The horse part in the name comes from it being used to help horses that are coughing or panting.
Their nut-like seeds are called conkers and are used in the traditional children’s game “conkers’ throughout Britain and Ireland. They are poisonous and should never be eaten.
It is widely cultivated throughout the temperate world, often planted in parks, streets, and home gardens.
It is hardy and able to grow well down to USDA zone 3.
Best grown in full sun in moist but well-drained, humus-rich soil. They will not tolerate droughts or areas with very hot summers.
Bleeding canker is a bacterial infection that is becoming a serious problem in Britain. It causes the infected tree’s bark to bleed a dark, sticky fluid.
It has been widely introduced in North America and is considered invasive in Oregon, USA.
Identifying Features of the Horse Chestnut
Horse Chestnut is a large tree with a rounded and domed crown with stout branches that may become pendulous with ascending tips in older specimens.
Leaves are oppositely arranged and palmately compound, up to 2 ft wide on 3 – 8” long petioles. They have 5 – 7 leaflets, each 5 – 12” long, with narrow to broadly cuneate bases, usually abruptly acuminate tips and irregularly serrated or repand margins.
Leaf scars on twigs have a distinctive horseshoe shape that can help identify them.
Flowers are showy white with a yellow or pink blotch at the petal base, with 20 – 50 flowers in erect panicles (branched inflorescences) 4 – 12” long.
Fruits are green spiky capsules that appear in groups of 1 – 5 per panicle. Each capsule contains one, or rarely 2 – 3 glossy nut-brown seeds that are ¾ – 1 ½” in diameter and have no woody pericarp.
Often Confused With: The Horse Chestnut is mostly confused with the Red Horse Chestnut, which is a smaller tree with 5 (7) ovate-oblong leaflets, each 6 – 10” long with doubly-serrated margins (the teeth have teeth), and showy red flowers in 6 – 8” long terminal panicles.
Other Common Names: European Horsechestnut, Buckeye, Conker Tree, Common Horsechestnut
Native Area: Albania, Bulgaria, mainland Greece, and North Macedonia.
USDA Growing Zones: 3 – 8
Average Size at Maturity: 50 – 75 ft tall, 40 – 70 ft spread
10. Red Horse Chestnut – Aesculus x carnea
Red Horsechestnut is a pretty hybrid cross of the Horse Chestnut from Europe and the smaller Red Buckeye native to eastern North America.
Its pink or red flowers and its medium size make it suitable as a park or border tree or a lovely shade or specimen tree for any home lawn or garden.
The fruits it produces can be messy and undesirable in some landscapes where maintenance is deemed an issue.
It can be propagated from seeds that will come out true.
Best grown in fertile, acidic soils, though it will tolerate less fertile soils with good drainage.
It is more drought-tolerant than other members of its genus but does not thrive in drought-prone environments.
It is more resistant to most diseases that affect other horse chestnuts, but occasionally powdery mildew causes early leaf drop.
So far, this tree seems to have little invasive potential.
Identifying Features of the Red Horse Chestnut
Red Horse Chestnut is a small to medium-sized tree with a pyramidal habit when young that becomes oval to rounded with age.
Leaves are dark green and palmately compound with 5 or occasionally 7 spreading ovate-oblong leaflets; each 6 – 10” long with doubly-serrated margins (the teeth have teeth of their own).
Showy red flowers appear in erect terminal panicles 6 – 8” long.
Fruit is a prickly capsule 1.5” wide, each containing 2 – 3 nuts.
Often Confused With: Red Horse Chestnut is often confused with Horse Chestnut, which is a larger tree with larger leaves with irregularly serrated or repand margins and larger terminal panicles of white or yellow flowers. It is also sometimes confused with Red Buckeye (Aesculus pavia) when it is young, but that one rarely grows more than 20 ft tall and usually remains as a multi-stemmed shrub, and it has slightly smaller leaves and terminal panicles of red flowers, but they are very tubular in shape.
Other Common Names: Horsechestnut.
Native Area: Natural hybrid discovered in Europe in 1812.
USDA Growing Zones: 5 – 8
Average Size at Maturity: 25 – 40 ft tall, 25 – 35 ft spread
Some Cultivars Available:
- Fort McNair Horse Chestnut Aesculus x carnea ‘Fort McNair’ is a medium-sized tree (to 35 ft tall) with pink spring blossoms, golden yellow fall color, and great disease resistance. Makes a great ornamental shade tree. Image via Nature Hills
- Briotti Red Horsechestnut Aesculus x carnea ‘Briotii’ is a small to medium-sized tree (to 30 ft tall) with reddish-pink and yellow flowers that are darker and larger than the typical hybrid species; nuts are not edible to humans, but squirrels love them! Image via Nature Hills
*Images Combined by Lyrae Willis for Tree Vitalize
Chestnut Tree Identification (With Photos)
Identifying Chestnut Trees by Their Leaf Arrangement
All true chestnuts and horse chestnuts have deciduous leaves.
It is easy to tell a true chestnut from a horse chestnut by its leaves.
True chestnuts have thin, somewhat leathery, simple leaves that are not compound and are arranged alternately on the branches or twigs.
Horse chestnut leaves are palmately compound leaves on long petioles (leaf stalks) arranged alternately on the branches. Each compound leaf has 5 – 11 thin and papery or somewhat leathery leaflets that may be sessile (stalkless) or on up to 1” long petiolules (leaflet stalks).
Palmately compound leaves are a type of compound leaf where all the leaflets radiate from a single point at the tip of the petiole.
Identifying Chestnut Trees by Their Leaf Shapes
Chestnut leaves, or horse chestnut leaflets, can be variable in size and shape.
They may be ovate (egg-shaped, widest at the base), obovate (like ovate but widest at the tip), lanceolate (like egg-shaped 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), elliptic (widest in the middle and narrowing at both ends, like an ellipse), or oblong (both sides are elongated and parallel, and both ends are more or less rounded).
Identifying Chestnut Trees by Their Leaf Tip (Apex)
Chestnut leaf tips (apices) do not vary much. They can be used to help identify it as a chestnut but are not very helpful in identifying the different types of chestnuts.
Their tips are either acute (the two sides are more or less equal and meet at an angle of less than 90°) or acuminate (the two sides taper before meeting at a very narrow angle). Acuminate tips can be long or short, or sometimes abrupt, where the tip is mostly rounded but abruptly forms a pointy tip.
Identifying Chestnut Trees by Their Leaf Base
Chestnut tree leaf bases show more variability between species and can often be used to help identify the chestnut at the species level.
Their bases may be cuneate (wedge-shaped, angled at less than 90°, sometimes called acute), rounded (having no angles or edges), truncate (appears as though abruptly cut off with a pair of scissors), cordate (heart-shaped, with a cleft where the petiole attaches creating a lobe on either side), or sometimes oblique (asymmetrical with one side longer, larger, or differently shaped than the other side).
Identifying Chestnut Trees by Their Leaf Margins
The leaf margins of true chestnuts are always serrated (jagged-toothed, like a saw) with sharp teeth. The serrations may be fine (have small teeth closer together) to coarse (often larger teeth that are farther apart). Their lateral veins typically end at the tip of the tooth and may or may not form a well-developed awn – a fine hair-like tip that can be useful in identifying different types of chestnut trees.
Horse chestnut leaflet margins are often repand or wavy-edged. Repand is similar to sinuate but more irregular, or like undulate, but where the leaf blade itself remains more or less flat. It is much easier to see in three dimensions than in photos.
Sometimes, horse chestnut leaflet margins may be irregularly serrated (having different sizes and spacing of teeth) or rarely entire (without teeth).
Identifying Chestnut Trees by Their Hairs (Trichomes) and Other Surface Features
Chestnut trees have a lot of different types of hairs and other features on their leaves, twigs, and fruits that can be used to help identify the different types of chestnut trees.
Plant hairs are not like animal hairs; they only slightly resemble them. They are more correctly referred to as trichomes, but we will use hair because it is more familiar to most people. Botanists have a lot of different terms they use to describe trichomes, each representing a very specific type of ‘hair’.
Chestnut hairs may be pubescent (very straight and soft to the touch), puberulent (like pubescent but shorter), pilose (like pubescent but longer), tomentose (long and curled but matted against the plant surfaces), villous (long and curled but not matted as in tomentose, or straight but entangled), or stellate (hairs are branched and arranged in a star-like pattern).
Any of these hairs may also be appressed or flattened against the surface. This differs from tomentose because they are not matted and are often one-directional).
Other surface features seen in chestnuts are gland dots that may appear like scales (flat trichomes that lack a stalk and sit directly on the plant surface) or more like obvious glands that may or may not show signs of secretion.
Identifying Chestnut Trees by Their Flowers
True chestnuts and horse chestnuts have very different flowers.
True chestnuts are monoecious, having separate male and female flowers on the same tree. In their case, they have many tiny white to yellowish, often fragrant, male flowers on a spike-like catkin of varying lengths.
Female flowers are held within a few cupules with 1 – 3 flowers per cupule, located at the base of the catkin. Those cupules later develop into fruits.
Horse chestnuts can be monecious like true chestnuts, or they can be bisexual, having both male and female organs in the same flower. Either way, their flowers are larger and much showier and may be white, pink, yellow, or red. They are arranged in erect terminal panicles (branched inflorescences) with many flowers per inflorescence.
Identifying Chestnut Trees by Their Fruits
Both true and horse chestnuts produce spiny fruits.
True chestnuts are true nuts; they have indehiscent hard shells (the pericarp) that encase a single seed. There are anywhere from 1 – 4 nuts produced per fruit that are encased in a cupule.
A cupule is a cup-like sheath that encases the nuts. Chestnut cupules are 2 – 4-valved and split open irregularly along these valves at maturity. Their cupules are densely spiny with branched and or interlocking spiny bracts that may or may not be hairy.
Horse chestnuts look superficially similar but are very different botanically. They are spiny capsules that contain 1 – 3 (rarely 4 – 6) seeds within. They are not nuts because the seeds within are not encased in a woody pericarp, and the capsule is formed differently than a cupule, even though they may appear somewhat similar.
Identifying Chestnut Trees by Tree Habit
Tree habit is the overall shape or form that a tree has when viewed from a distance.
Chestnut tree habit tends to be similar between species, but it can still be used to help identify the tree you are looking at as a chestnut tree.
As they mature, they tend to become open and spreading or rounded.
They typically have straight trunks but with branches fairly low on their trunk that contribute to these rounded and spreading forms.
Chestnuts resprouting after being hit by blight or other damage to the main trunk tend to remain as multi-stemmed shrubs.
Identifying Chestnut Trees by Their Bark
Chestnut bark can vary between species and is also sometimes used in conjunction with other clues to help identify the different types of chestnut trees.
All chestnut bark starts out smooth when it is young, and it is usually gray but is sometimes brown or brownish.
As it matures, the bark typically develops vertical grooves in characteristic patterns.
Some bark develops regular vertical grooves or furrows lengthwise down the tree. Other bark becomes more finely and shallowly grooved.
Sometimes the grooves are irregular without a distinguishable pattern.
Some bark has grooves and ridges that interlace with each other creating V or diamond-shaped patterns in the trunk surface.
Often the grooves develop vertically, but they twist spirally around the tree. This spiral groove pattern is fairly unique to true chestnut trees; it is not often seen in other tree genera or families and could be a useful clue that you are looking at a true chestnut tree.
Finally, some bark remains more or less smooth as it matures. This is typically seen in the more shrub-like species that do not develop bark thick enough to form ridges and furrows.
Horse chestnut bark tends to be smooth when young but develops scaly irregular to rectangular plates when it matures that often exfoliate slightly, lifting at the edges. Smaller, shrubbier members of the Aesculus genus often retain their smooth bark.
Cheerful Chestnut Trees
Growing Chestnut Trees in Your Garden
It is easy to grow a chestnut tree if the conditions are right. It is a low-maintenance tree that will provide you with beauty, shade, fruits, and wildlife values, all with relatively little effort.
If you are going to grow a chestnut tree, be sure to do a little research to ensure your tree establishes successfully.
The first thing to know is your USDA Planting Zone. Make sure that your chosen tree will survive in your climate.
All chestnuts generally do well in zones 5 – 8, some do well in 4 and others in 9, so read up on your chosen species or cultivar. Horse chestnuts are hardier, some to zone 3, but some of them are also invasive.
Next, you must check your chosen tree’s soil, light, and moisture requirements and compare that to your site. Check out How to Pick A Tree For Your Yard for more information on choosing the right tree for the right spot in your yard.
Most chestnut trees prefer moderately moist to dry soils in the acidic to neutral pH range, but otherwise, they tend not to be very picky about soil type. Some will tolerate drought very well, while others will not.
Most chestnuts require full sun, but some will tolerate a little shade, though all will do poorly in full shade.
You should always try to choose species native to your area to enhance biodiversity and wildlife values. Wherever native trees are available to you, I strongly encourage you to plant them. Sadly, in North America, if you want nut production, that could be challenging, but you could always choose one of the newer resistant cultivars.
Fortunately, none of the true chestnut species seem to have much invasive potential outside their native range, so they should be safe to plant.
The Horse Chestnut, on the other hand, has shown significant invasive potential.
About Chestnut Blight – History, Symptoms, Treatments
Chestnut Blight was accidentally introduced to North America in 1904 when Japanese Chestnut trees were introduced for commercial production. By 1905 it was already discovered in the New York Zoological Garden. By 1940, only a handful of the mature American Chestnut trees out of an estimated four billion trees were still healthy.
Chestnut Blight is caused by Cryphonectria parasitica, a parasitic fungus. The fungus spreads from tree to tree by ascopores from the fungus that are dispersed in the wind as well as birds and insects.
Since infection is limited to the spread of these ascopores, it has allowed the occasional isolated tree to survive, but there is virtually no resistance in most American Chestnuts.
Japanese and Chinese Chestnuts evolved with the fungus and are resistant to it; when they get infected, it is usually not fatal.
When the blight infects a tree, it forms cankers in the inner bark where its mycelium overwinters. These become visible when the bark expands and splits open, showing the canker and rotting wood beneath.
The following spring, the mycelium in the cankers produce fruiting bodies that allow the infection to spread.
Meanwhile, the cankers continue to form and expand and end up girdling the tree and stopping the flow of nutrients and water, and the tree dies even though the root system still remains alive.
Since chestnuts can resprout from their stumps, they are still alive in the forests, growing as resprouts. However, non-resistant varieties all tend to get re-infected before the resprouts reach sexual maturity.
Research is being done by hybridizing the American Chestnut with the Chinese Chestnut to try to get a mostly American Chestnut genetic profile with just enough Chinese Chestnut genetics to resist the blight.
Interesting Facts About Chestnut Trees
Chestnut trees produce more fruit in colder climates in their range, opposite to many food-producing trees, which tend to be more productive when warmer.
Chestnut trees typically live 200 – 800 years in the wild.
The Hundred-Horse Chestnut (not a Horse Chestnut, a European Chestnut!) is the oldest and largest chestnut tree in the world. It is found on the eastern slope of Mount Etna in Sicily. It is 2000 – 4000 years old and holds the Guinness World Record for the “Greatest Tree Girth Ever”, having a circumference of 190 ft when it was measured in 1780 before it split into multiple large trunks.
The American Chestnut was once a dominant large hardwood tree covering about 500,000 square miles of eastern North American forests. It was wiped out by an accidentally introduced blight in less than 40 years.
Human Uses of Chestnut Trees
Chestnuts are a valuable source of delicious and nutritious nuts. They are high in starch, Vitamin C, Vitamin B complex, magnesium, potassium, and iron. They can be consumed raw, roasted, or dried and ground into flour.
The bark and wood are rich in tannic acid and were routinely used in the past for tanning leather.
The wood is of high quality for lumber. It is hard, strong, dense, and light in color. It is used in furniture making and house construction, as well as fencing, barrels, and more.
Herbalists use the leaves to treat diarrhea, constipation, coughs, colds, flu, fever, hypertension, indigestion, and more.
Leaves are also used in the cosmetic industry and in shampoo products.
Horse Chestnut seeds are toxic but were once eaten in Japan after leaching the toxins out of them.
Wildlife Values Chestnut Trees Provide
Chestnut trees provide important structural diversity to the forests they often dominate(d), providing habitat and temporary shelter for countless native birds, mammals, arboreal rodents, and invertebrates.
Squirrels, bears, chipmunks, birds, and numerous other creatures routinely feed on the nutritious nuts, and deer sometimes feed on their leaves.
Flowers are an important source of nectar and pollen for numerous pollinating insects, including bees, butterflies, moths, and more.
Chestnut trees are beautiful, cheerful trees that can brighten any landscape and fill the hungry bellies of wildlife and people alike. I hope you have enjoyed learning about this beautiful tree.
Now you can go out and use your skills to identify the chestnut trees around you, or maybe grow your own in your yard for you and future generations to enjoy!
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