.^SCULUS 



^sculus, Linnaeus, Gen. PI. 109 (1737); Bentham et Hooker, Gen. PL i. 398 (1862). 

 Pavia, Boerhave. ex Miller, Gard. Diet. ed. 6 (1752). 



Deciduous trees and shrubs, belonging to the natural order Sapindaces, some 

 authorities, however, making the genus the type of a distinct order Hippocastaneae. 

 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 ^sculus ' 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, whicli have tri-foliolate leaves, are now separated as a distinct genus, Billia. 



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