ÆSCULUS
- Æsculus, Linnæus, Gen. Pl. 109 (1737); Bentham et Hooker, Gen. Pl. 1. 398 (1862).
- Pavia, Boerhave, ex Miller, Gard. Dict. ed. 6 (1752).
Deciduous trees and shrubs, belonging to the natural order Sapindaceæ, some authorities, however, making the genus the type of a distinct order Hippocastaneæ. Leaves in opposite decussate pairs, without stipules, stalked, digitately compound; leaflets five to nine, serrate in margin, pinnately veined. Branchlets stout, terete, with large triangular leaf-scars. Buds large, of numerous decussately opposite scales which are homologous with leaf-bases, the outer deciduous, dry or resinous, the inner accrescent and often brightly coloured.
Flowers in large terminal racemes or panicles, appearing later than the leaves, of two kinds, hermaphrodite and staminate, on the same plant; placed in the axils of minute caducous bracts on stout jointed pedicels. Calyx imbricate in bud, five- or two-lobed, the lobes unequal, united with an hypogynous annular disc in the hermaphrodite flowers. Petals four to five, imbricate in bud, alternate with the calyx lobes and inserted on the disc. Stamens five to eight, usually seven, inserted on the inner margin of the disc, unequal in length; filaments filiform; anthers two-celled, sometimes glandular at the apex. Ovary three-celled, rudimentary in the staminate flowers, each cell containing two ovules. Style slender, elongated, generally curved. Fruit a capsule; prickly, roughened, or smooth; coriaceous; three-celled, three-seeded, and three-valved, or by abortion one- to two-celled and one- to two-seeded, the remains of the abortive cells and seeds usually remaining visible. Seeds without albumen, rounded or flattened by mutual pressure; seed-coat brown and coriaceous, marked by a large whitish hilum. Cotyledons thick and fleshy, unequal, cohering together by their contiguous faces, remaining in the seed-coat during germination.
About twelve species of Æsculus[1] are known to occur in the wild state. They are natives of North America, Europe, and Asia. The genus was formerly divided into two sections, Pavia, with smooth fruit, and Hippocastanum, with spiny fruit; but this division is not a natural one. The following synopsis groups the species under sections, which are more natural, being dependent on the characters of the flowers and buds:—
I. Hippocastanum. Buds viscid. Calyx irregularly campanulate, four- to five-
- ↑ The two Mexican species, which have tri-foliolate leaves, are now separated as a distinct genus, Billia.
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