709 TREES OF NOKTIi A.MKIiU'A 



rounded at base, coarsely serrate above the middle, or nearly entire, when they unfold 

 hoary-tomentose below and densely pubescent above, occasionally deeply lobed, glabrous 

 on the upper surface except along the midrib and veins, thickly coated on the lower sur- 

 face with matted pale hairs and furnished with large axillary tufts. Fruit on pubescent 

 pedicels, puberulous or nearly glabrous, not constricted or rarely slightly constricted at 

 base. 



A tree, 20-50 high, with dark bark, hoary-tomentose bi-aiichlets and winter-buds. 



Distribution. California, valley of the lower Sacramento River and the interior valleys 

 of the coast ranges from the Bay of San Francisco to Santa Barbara County and in ele- 

 vated canons on the western slopes of the San Bernardino Mountains; widely distributed 

 but nowhere abundant. 



Occasionally planted in California. 



XXXVI. HIPPOCASTANACE^E. 



Trees or rarely shrubs, with stout terete branchlets conspicuously marked by triangu- 

 lar leaf-scars, fetid bark, thick fleshy roots, and large scaly winter-buds, the inner scales ac- 

 crescent with the young shoots and often brightly colored. Leaves opposite, digitately 

 compound, without stipules, deciduous; leaflets 3-9, lanceolate or ovate, serrate, pin- 

 nately veined. Flowers polygamo-moncecious, showy, white, red, or pale yellow, on 

 stout jointed pedicels from the axils of minute caducous bracts, racemose or nearly uni- 

 lateral on the branches of large terminal thyrsi or panicles, appearing later than the leaves, 

 only those near the base of the branches of the inflorescence perfect and fertile; calyx 5 

 or rarely 2-lobed, the lobes imbricated in the bud, unequal, campanulate or tubular, 

 the lobes imbricated in the bud, mostly oblique or posteriorly gibbous at base; disk 

 hypogynous, annular, depressed, lobed, more or less gibbous posteriorly; petals 4 or 5, 

 imbricated in the bud, alternate with the lobes of the calyx, deciduous, the anterior 

 petal often abortive, unguiculate, the margins of the claw commonly involute; stamens 

 6-8, rarely 5, generally 7, inserted on the disk, free, unequal; filaments filiform; anthers 

 ellipsoid, glandular-apiculate, attached on the back below the middle, introrse, 2-celled, the 

 contiguous cells opening longitudinally; ovary sessile, oblong or lanceolate, 3-celled, echi- 

 nate or glabrous, rudimentary in the staminate flower; style slender, elongated, generally 

 more or less curved; stigma terminal, entire, mostly acute; ovules 2 in each cell, borne on the 

 middle of its inner angle, amphitropous, the upper ascending, the micropyle inferior, the 

 lower pendulous, the micropyle superior. Fruit an echinate or smooth coriaceous capsule, 

 3-celled and loculicidally 3-valved, the cells 1-seeded by abortion, often by suppression 1 

 or 2-celled, and then 1 or 2-seeded, the remnants of the abortive cells and seeds commonly 

 visible at its maturity. Seeds without albumen, round when one is developed, or, when 

 more than one, flattened by mutual pressure; seed-coat coriaceous, dark chestnut-brown 

 or pale orange-brown, smooth and lustrous, with a broad opaque light-colored hilum; em- 

 bryo filling the cavity of the seed; cotyledons very thick and fleshy, often conferruminate, 

 unequal, incurved on the short conic radicle, remaining under ground in germination; 

 plumule conspicuously 2-leaved. 



The Horsechestnut family is composed of the widely distributed genus Aesculus and 

 of Billia Peyr., a genus of two species of Mexican and Central American trees, differing 

 from Aesculus in its 3-foliolate leaves. 



1. AESCULUS L. 



Characters of the family ; leaves 5-9-foliolate. 



Aesculus with fifteen or sixteen species, is represented in the floras of the three conti- 

 nents of the northern hemisphere and is most abundant in the southeastern United States. 

 It produces soft straight-grained light-colored wood and bitter and astringent bark. The 

 seeds contain a bitter principle, aesculin. Aesculus Hippvcastauum L., of the mountains 



