Aesculus spp.—Horse-chestnut; buckeye
FAMILY: Hippocastanaceae—the Horse-chestnut Family
This family consists of trees or shrubs with opposite, palmately compound leaves composed of 5 to 7 serrated leaflets. Flowers are zygomorphic, perigynous with an extra staminal, often 1-sided disk; sepals: 5, united at least half their length; petals: 4 or 5, white, yellow, or red, clawed; stamens: 5-8. with elongated and often exserting filaments; ovary: 3-celled, 2 ovules in each chamber; style: elongate; fruit: a leathery, globose capsule bearing sharp spines when young, becoming smooth in some species, eventually opening by 3 valves; seeds: 1 (subglobose), 2 (hemiglobose), or 3 (flattened sides), glossy brown, bearing a large conspicuous, light-brown scar, usually about 2.5 cm in diameter.
PHENOLOGY: Depending on the species, the flowering period can be May to June.
DISTRIBUTION: Some species are cultivated; of these a few occasionally escape and become established. Other taxa occur naturally on moist, alluvial soil, in rich moist woods, or along streams.
PLANT CHARACTERISTICS: Aesculus hippocastanum L. is the common horse-chestnut. Widely cultivated, it is a tree to 25 m with variously colored, double-flowered and hybrid forms available. Older stock has the white upper and lateral petals marked with red or yellow at the base; petals number 5. Aesculus glabra Willd. (Ohio buckeye) is a small tree with yellow flowers found predominantly along river banks and in moist woods in western Pennsylvania and now introduced in the eastern part of the state; it has 4 greenish-yellow petals, long-exserted stamens, and spined fruit; Aesculus octandra Marsh. (sweet buckeye) has 4 yellow (sometimes purple or red) petals, stamens barely exserted, and smooth fruit. Cultivated species of Aesculus include the dwarf or bottle brush buckeye (A. parviflora Walt.) with white flowers and long-exserted stamens and the red horse-chestnut (A. carnea), a hybrid tree from A. hippocastanum x A. pavia
POISONOUS PARTS: Nuts (seeds), stump sprouts, bark, flowers, leaves, dried fruits, and young growth are dangerous.
SYMPTOMS: Experimental feeding of A. pavia L. produced the following symptoms on ingestion at the rate of 1% of the animal's weight: incoordination, nervous twitching of muscles, sluggishness, and excitability. It is reported that flowers are poisonous to honey bees; poisoning of humans eating honey produced from the nectar of California buckeye has been reported. In Europe, ingestion of the seeds has reportedly killed children, and leaves and dried fruits have caused loss of cattle. Other symptoms may include dilated pupils, vomiting, diarrhea, depression, paralysis, and stupor.
POISONOUS PRINCIPLES: Alkaloids, glycosides and saponins are responsible for toxicosis. One important constituent is aesculin (esculin), a lactone glycoside and hydroxy derivative of coumarin, This molecule shows a chemical relationship with the toxic substance in spoiled sweetclover hay (Melilotus spp,), which also contains coumarin glycosides. Sweet-clover poisoning is a hemorrhagic disease fatal to cattle. Loss is due to internal or external hemorrhage.
CONFUSED TAXA: The erect, large, many-flowered inflorescences may superficially resemble those of catalpa trees (Cata/pa spp.), which have large, simple, heart-shaped leaves, and the Princess Paulownia tree (Paulownia tomentosa (Thunb.) Steud.), which also has large, simple leaves. Aesculus fruits may be confused with those of several species of trees. American beech (Fagus grandifolia Ehrh.) has small, sharply 3-angled fruits. They are l-seeded and normally born in pairs within an accrescent, 4 valved involucre. The prickles of the fruit are 4-10 mm, erect to spreading or recurved and numerous. Another genus, Castanea, the chestnut, bears solitary 2-or 3-seeded fruits. These are enclosed within an accrescent, long-spined, 2-to 4- valved involucre; the stiff spines are numerous, more than 10 mm long, and often branched from the base.
SPECIES OF ANIMALS AFFECTED: All classes of livestock and humans are potential victims of Aesculus poisoning upon consumption of this plant.
TREATMENT: (11a)(b); (26)
OF INTEREST: Aesculus was a source of medicinal preparations in past years. The common name horse-chestnut is derived from the belief that Turks fed a kind of "chestnut" to their horses to enable them to breathe more easily.