BIGNONIACE^E 869 



CONSPECTUS OF THE ARBORESCENT GENERA OF THE UNITED STATES. 



Fruit a linear woody capsule; ovary 2-celled; leaves thin, deciduous. 



Stamens 4; staminodium 1; leaves linear, often alternate or scattered. 1. Chilopsis. 



Stamens 2; staminodia 3; leaves oblong-ovate, mostly opposite. 2. Catalpa. 



Fruit a berry; stamens 4; staminodium 1; ovary 1-celled; leaves coriaceous, persistent. 



3. Enallagma. 



1. CHILOPSIS D. Don. 



A tree, with slender terete branches, without a terminal bud, minute compressed rusty- 

 pubescent axillary buds covered by several imbricated scales, those of the inner rows ac- 

 crescent, deeply furrowed bark, soft coarse-grained dark-colored wood, and fibrous roots. 

 Leaves opposite, alternate or scattered, involute in the bud, linear or linear-lanceolate, 

 long-pointed, entire, 3-nerved, the lateral nerves obscure, reticulate-venulose, thin, light 

 green, smooth or glutinous, short-petiolate or sessile from an enlarged base, deciduous, in 

 falling leaving small elevated suborbicular scars. Flowers on slender pedicels from the 

 axils of ovate acute scarious tomentose deciduous bracts and bibracteolate near the middle, 

 in short puberulous crowded racemes or rarely panicles terminal on leafy branches of the 

 year; calyx pale pubescent, puberulous or rarely glabrous, closed before anthesis into an 

 ovoid rounded apiculate bud splitting to the base into 2 ovate divisions, minutely toothed 

 or long-pointed at apex, the upper with 3, the lower with 2 rigid teeth, membranaceous, 

 dark green; corolla white shaded into pale purple or rarely white, slightly oblique, enlarged 

 and blotched with yellow in the throat, the limb undulate-margined, the upper lip 2-lobed, 

 the lower unequally 3-lobed, the central lobe much longer than the others; stamens 4, in- 

 serted in 1 row near the base of the corolla in pairs, introrse; filaments filiform, glabrous, 

 the anterior nearly twice as long as the posterior; anther oblong, the cells divergent in an- 

 thesis; staminodium 1, posterior, linear, acute; disk thin, nearly obsolete; ovary 2-celled, 

 conic, glabrous, divided at apex into 2 ovate flat rounded lobes; ovules inserted in many 

 series on a central placenta. Fruit a slender elongated thin-walled capsule gradually nar- 

 rowed from the middle to the ends, splitting into 2 concave valves. Seeds numerous, in- 

 serted in 2 ranks near the margin of the thin flat woody septum free from the walls of the 

 capsule, compressed, oblong; seed-coat thin, light brown, longitudinally veined, produced 

 into broad lateral wings divided at their rounded ends into a long fringe of thin soft white 

 hairs; cotyledons plane, broader than long, slightly 2-lobed, and rounded laterally; radicle 

 short, erect, turned toward the oblong basal hilum. 



The genus is represented by a single species, a native of the region adjacent to the bound- 

 ary between the United States and Mexico. 



The generic name, from x^os and fr/'ts, is without special significance. 



1. Chilopsis linearis DC. Desert Willow. 



Leaves unfolding in early spring, 6'-12' long and \'-\ r wide; deciduous during the fol- 

 lowing winter. Flowers appearing in early summer in racemes or narrow panicles 3'-4' 

 long, and continuing to open for several months in succession, f '-1|' long and f '-!' across 

 the expanded lobes of the corolla. Fruit ripening in the autumn, 7 '-12' long, \' thick in 

 the middle, persistent on the branches during the winter; seeds \' long and \' wide. 



A tree, 20-30 high, with a trunk usually more or less reclining, often hollow, and some- 

 times a foot in diameter, slender upright branches forming a narrow head, and branchlets 

 glabrous or covered with dense tomentum when they first appear, light chestnut-brown 

 during their first season, later becoming darker and tinged with red, or sometimes ashy 

 gray; or often a straggling shrub. Bark of the trunk \'-\' thick, dark brown, and divided 

 into broad branching ridges broken on the surface into small thick plate-like scales. Wood 

 soft, not strong, close-grained, brown streaked with yellow, with thin light-colored sap- 

 wood of 2 or 3 layers of annual growth. 



Distribution. Banks of streams, and depressions in the desert, usually in dry gravelly 



