HIPPOC AST AN ACE^ 



643 



Acer Negundo, var. Californicum, Sarg. Box Elder. 



Leaves trifoliolate, with larger more coarsely serrate and more frequently lobed 

 leaflets densely coated at maturity on the lower surface with pale pubescence. 



A tree, 50-60 high, with darker colored bark, winter-buds covered with thick 

 tomentum, and pubescent branchlets and ripe fruit. 



Distribution. Valley of the lower Sacramento River and the interior valleys 

 of the coast ranges from the Bay of San Francisco to about latitude 35^, and in high 



canons on the western slopes of the San Bernardino Mountains, California; connected 

 by intermediate forms from Arizona to Texas, the Indian Territory, and Missouri, 

 with the eastern tree. 



Often planted in the United States as an ornamental tree or for wind-breaks in 

 the treeless central part of the continent, and largely, with numerous varieties, as an 

 ornamental tree in western and northern Europe. 



XXXIV. HIPPOCASTANACEiE. 



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

 triangular leaf-scars, fetid bark, thick fleshy roots, and large scaly winter-buds, 

 the outer scales sometimes coated with resin, the inner accrescent with the 

 young shoots and often brightly colored. Leaves opposite, digitately compound, 

 without stipules, deciduous ; leaflets 5-9, lanceolate or ovate, serrate, pinnately 

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

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

 nearly unilateral on the branches of large terminal thyrsi or panicles, appear- 

 ing later than the leaves, only those near the base of the branches of the inflo- 

 rescence perfect and fertile ; calyx 5 or rarely 2-lobed, the lobes imbricated in the 

 bud, unequal ; calyx campanulate or tubular, 5-lobed, the lobes imbricated in 

 the bud, mostly oblique or posteriorly gibbous at the 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 one often abortive, unguiculate, the margins of the claw commonly 

 involute ; stamens 6S, rarely 5, generally 7, inserted on the disk, free, unequal ; 

 filaments filiform ; anthers elliptical, gland ular-apiculate, attached on the back 



