Common Horse Chestnut

Arbor walk #64, Treekeeper ID #5490

Despite being widely planted as an easy-to-grow shade tree for streets and landscapes throughout the Midwest, the Common Horse Chestnut is originally native to the Balkan region of Europe. The tree features showy white flowers in spring which in summer transition into fruit, consisting of one or two seeds encased in a spiny husk.

Horse Chestnuts are actually part of the soapberry family and are entirely unrelated to chestnuts, which are part of the beech family. Like the closely related buckeyes, the fruit of these trees is not edible and is poisonous. On this particular specimen one can see the remains of an invasive Euonymus vine which had been growing on the tree. It is not uncommon to see many of these vines wrapped around the surface of a tree causing damage to the tree and its bark; however, in this instance the Euonymus vine fully pierced through the heartwood at the base of the tree. Despite this, the tree recovered speedily once the vine was killed.

Common Name	Common Horse Chestnut, European Horse Chestnut
Latin Name	Aesculus hippocastanum
Indigenous Name(s)
Cultivar/Variety
Commercial Name

Global Distribution

Where to find Arbor Walk #64 on WashU campus

Our Common Horse Chestnut in space

GPS Coordinates

N/A

Percent Concrete

N/A

Distance to Buildings

Year	Close Building #1	Close Building #2	Close Building #3
2020	Whittemore House, 1.62 m	Stix International House, 51.82 m	Harbison House, 53.96 m

Distance to Other Species

Year	Close Species #1	Close Species # 2	Close Species # 3
2020	Japanese Maple, 7.15 m	Eastern Redbud, 7.32 m	Eastern Arborvitae, 9.35 m

Our Common Horse Chestnut through time

Standard Measurements

Year	Height (m)	DBH (cm)	Caliper (m)	Crown Diameter N-S (m)	Crown Diameter E-W (m)	Average Crown Diameter (m)
2020	15.35	57.00	N/A	13.92	13.92	13.92
2023	19.41	58	N/A	13.06	12.53	12.795

Nests and Pests

Year	Description
2020	Advanced bacterial rot at some spots, with reddish weeping ‘sap’ present at these wounds 1 white, saucer-shaped spider eggscase fused to trunk Some old wounds have been chewed open into larger hollows, housing lots of fungal/algal growth

How to identify a Common Horse Chestnut

Leaf Identification

The leaves of the Common Horse Chestnut are palmately compound with 7 obovate to ovate leaflets that are 4″ to 10″ long. The middle leaflet is almost always the longest, and they progressively get shorter the closer it gets to the petiole. The margins are doubly serrated, and the venation is pinnate. They are a light green in spring, dark green in summer, and turn yellow and brown in the fall. The leaf arrangement is opposite (leaf stems always branch off the stem opposite from another leaf stem).

Diseased Leaf of Arbor Walk #64
Underside of Leaf from Arbor Walk #64
Leaflet of Arbor Walk #64

Twig and Bud Identification

The twigs of the Common Horse Chestnut are brownish-gray and have raised lenticels (pores). The buds are large, shiny, and reddish-brown.

Twig of Arbor Walk #64
Branch & Twigs of Arbor Walk #64
Bud of Arbor Walk #64
Twig of Arbor Walk #64

Bark Identification

The Common Horse Chestnut’s bark is grayish-brown to black broken into scaly plates.

Bark of Arbor Walk #64

Fruit Identification

The fruit of the Common Horse Chestnut is a shiny, dark brown nut with a tan scar. It is surrounded by very spiny and leathery husk. They ripen in the fall.

Fallen, Old Fruit without Husk of Arbor Walk #64
Immature Fruit of Arbor Walk #64

Flower Identification

The flowers of the Common Horse Chestnut are upright terminal panicles. They bloom in mid spring. They are white with red or yellow markings.

[photo forthcoming]

Relationship of Aesculus hippocastanum to other species in the arboretum

Additional resources on the Common Horse Chestnut