Aesculus hippocastanum (Horse Chestnut)

Plant Info
Also known as:
Genus:Aesculus
Family:Sapindaceae (Soapberry)
Life cycle:perennial woody
Origin:Europe
Habitat:sun; urban landscapes
Bloom season:May - June
Plant height:30 to 50(100) feet
Wetland Indicator Status:none
MN county distribution (click map to enlarge):Minnesota county distribution map
National distribution (click map to enlarge):National distribution map

Pick an image for a larger view. See the glossary for icon descriptions.

Detailed Information

Flower: Flower shape: 4-petals Flower shape: 5-petals Flower shape: irregular Cluster type: panicle

[photo of flowers] Showy, loose to dense, rounded to semi-pyramidal branching clusters 6 to 10+ inches long at branch tips. Flowers are intermixed staminate (male), pistillate (female) and perfect (both male and female parts), 1 to 1¼ inches across with 4 or 5 petals. Petals are spreading, irregularly rounded, white with a red to pink or yellowish blotch towards the base, the outer surface smooth or covered in white woolly hairs. The 7 stamens are longer than the petals, flaring out and up from the center, hooking up near the tip, and white with deep orange tips (anthers). The single style is white with an obscure stigma at the tip and longer than the stamens. The calyx cupping the flower is bell shaped with 5 lobes, about ¼ as long as the petals.

Leaves and bark: Leaf attachment: opposite Leaf type: compound Leaf type: palmate

[photo of leaves] Leaves are opposite, long stalked, palmately compound with 5 to 9 leaflets, commonly 7. Leaflets are 4 to 9½ inches long, 2 to 4½ inches wide, somewhat wedge-shaped, widest near the tip (obovate), rounded at the tip end with an abrupt taper to a short point, and a long taper to the base. Edges are a bit wavy, finely toothed or double-toothed. The upper surface is hairless or with sparse white hairs, the lower densely covered in rust-colored hairs, more so near the base and in vein axils. Fall color is gold to red-orange.

[photo of twig, bud and leaf scar] Young twigs and branches are stout, brown with very fine short hairs and scattered lenticels (pores), becoming smoother with age, the lenticels more pronounced. Terminal buds are very large especially in full sun specimens, to 1½ inches long, smaller below, egg shaped with a blunt tip. Bud scales are also broadly egg-shaped, tips rounded, dark reddish brown with a sticky, resinous coat, tight against the bud. Leaf scars are broadly smiley faced with 6 to 8 conspicuous vascular bundle scars.

[photo of trunk] Branch bark becomes rougher with conspicuous light and darker gray vertical lines, older bark breaks up into thick, flaky gray plates. There are few specimens to observe a typical trunk diameter for Minnesota, but in its native European range it can reach 16 feet diameter at breast height (dbh) though 6 feet is more typical.

Fruit: Fruit type: capsule/pod

[photo of developing fruit] Fruit is a fleshy, globular capsule 2 inches diameter, golden brown, the surface leathery and covered in stiff spines to 1/3 inch long. Seed is a large, shiny, dark reddish-brown nut with a large circular "eye" that sometimes covers nearly half the surface. Each fruit has 1 to 3 nuts.

Notes:

Introduced to North America for ornamental purposes from milder, temperate regions of southeastern Europe and Asia, Horse Chestnut has historically performed poorly in much of Minnesota due to winter hardiness problems. Where it is successful as a specimen tree, the site is typically sheltered from weather extremes. The specimen we photographed was on the University of Minnesota's St. Paul campus, sheltered in between classroom buildings. Still relatively small, it has already suffered some trunk die-out and, as can be noted in our winter image below, it also did not have an adequate growing season to fully harden off and shed its leaves before the onset of winter. Where it is hardy, it is noted for its extremely broad, dense crown and beautiful spring floral display. Interestingly, Horse Chestnut is considered Threatened or Endangered in much of its native range, where it is a tree of deciduous forests and the rocky slopes of valleys and canyons.

It is published here in our field guide mostly to prevent confusion with the far more common US native Ohio Buckeye (Aesculus glabra). Horse Chestnut has white flowers and leaflets are all typically widest near the tip with an abrupt taper to a short point, where Ohio Buckeye has pale yellow flowers and leaflets have a longer taper at the tip. Horse Chestnut buds are also up to 1½ inches long, rather shiny and sticky with 6 to 8 vascular bundles in the leaf scar, where Ohio Buckeye buds are about ½ inch long, dull and smooth and have 3 bundles in leaf scars.

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More photos

Photos by Peter M. Dziuk taken at the University of Minnesota St. Paul campus.

Comments

Have you seen this plant in Minnesota, or have any other comments about it?

Posted by: Jan Kulda - near Willow Lake, SD
on: 2020-06-11 00:04:46

About 50 miles to the west of the Minnesota border, my parents' farm has a lovely horse chestnut tree that is at a minimum 60 years old. My Dad could give you a better estimation of it's age. Please let me know if you'd like more information about the tree. (I live in Maple Grove, MN.)

Posted by: Pam Macik - Hector, MN. South central
on: 2020-07-24 07:42:09

We have a horse chestnut in our backyard and just wondered what you do with the nut??

Posted by: Steve Clayton - St. Louis Park
on: 2020-09-04 14:18:19

We have a 25- to 30-foot tall chestnut tree that volunteered in our vegetable garden about 25 years ago. It has leaves with 5 "fingers". The flowers are white with yellow highlights. The pods are egg-shaped with minor spikes, generally tan-colored and can contain up three chestnuts. The bark is gray and relatively smooth. Two blocks away is a decidedly different version of our tree: Larger leaves with seven "fingers"; Larger flowers with pinkish highlights; smaller, bright green, round pods with larger spikes; rough, flaky bark. Anyone know the difference or origin of the two?

Posted by: K. Chayka
on: 2020-09-04 18:46:07

Steve, the number of leaflets varies from 5 to 9. Read the Notes section above, comparing horse chestnut and Ohio buckeye.

Posted by: Courtney Hall - MINNEAPOLIS
on: 2020-09-07 10:47:12

Saw 2 young trees on a walking path in Theo Wirth on a trail ascending away from the Quaking Bog.

Posted by: Jeff Hartmann - Crow Wing County south of the small town of Pine Center.
on: 2021-09-27 10:06:33

As an elementary school teacher, in the fall I sent every student in our school home with a horse chestnut every year and told them to be a squirrel and plant the nut in the ground. Much to me surprise, 20 years into my teaching career, I received a photograph of a former student standing next to a 15 foot tall chestnut tree that he had planted some years before. What a "teacher's moment" that was. I have continued in my retirement to plant the nuts - give the nuts away to anyone that will plant them - and give young trees in pots for people to plant. My yard is full of young and teenage horse chestnut trees. Now my question - when is the best time to plant chestnuts - before or after the first frost. Any planting tips would be appreciated.

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