Horse-chestnut, the popular name of a genus of trees belonging to the order Sapindaceae, probably derived from the resemblance of their seeds to the fruits of the true or sweet chestnut, a totally distinct tree, whilst this is inedible - "horse" being a contemptuous prefix signifying "coarse," as in horse-radish, or as the "dog" in "dog-violet." They have smooth bark; opposite, exstipulate, palmate leaves of 5 to 9 leaflets; a five-lobed calyx; 4 to 5 petals; 5 to 8 stamens; and a three-chambered single-styled ovary, which forms a leathery dehiscent capsule containing several large exalbuminous seeds. The common horse-chestnut, AEscnlus Hippocastaneum, is not certainly known in a wild state. It grows 50 or 60 feet high, with branches which ascend and then curve downwards and outwards, and very large buds, which are very glutinous in spring. There are typically 7 obovatecuneate leaflets, which are somewhat exceptional in hanging downwards in the bud and rising as they expand. The inflorescence is a conspicuous pyramidal raceme of cymes, terminating a branch:
the petals are white, flecked with pink and yellow; and the stamens are generally of the exceptional number seven, two being intercalated between the norrneil five. Only the lower flowers produce fruit, the upper ones being staminate. The fruit is spinous, and the six ovules only give rise to one, two, or three of the dark-brown seeds. The soft white wood is of little use. The "nuts" are too bitter for human food, but are eaten by goats and deer. Pure starch can be prepared from them, and, when mixed with twice the quantity of wheat flour, they afford a strong bookbinder's paste. Several species are natives of North America, where they are known as Buck-eyes, some of them, having yellow, pink, or scarlet blossoms.