Aesculus hippocastanum is a tree to 25 m tall; bark brown, flaky; winter buds large, blackish, sticky.
Leaves deciduous, opposite, palmately compound with 7 leaflets, 10-25 cm long, widest above middle, tapered to base, tip abruptly pointed, secondary veins numerous, parallel, margin toothed.
Flowers white, marked with red or yellow, irregular, sepals 5 overlapping, fused to form a lobed tube, petals 5; inflorescence cone-shaped, large, many flowered.
Fruit spiny, rounded, a 3-parted capsule, to 5 cm with one large brown seed.
Wetland status: NL.
Frequency in New York City: Occasional.
Habitat: Escaped from cultivation, usually in regenerated woodlands.
Notes: Nut is apparently poisonous. Toxicity is due the glycoside aesculin (6-beta-glucosido-7-hydroxycoumarin) (Kingsbury 1964). A host tree of the Asian longhorn beetle, Anoplophora glabripennis (see Norway maple).