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 accrescent, 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, inserted 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 anthesis; 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 narrowed from the middle to the ends, splitting into 2 concave valves. Seeds numerous, inserted 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 boundary between the United States and Mexico.
The generic name, from χεῖλος and ὄψις, is without special significance.
1. [Chilopsis linearis] DC. Desert Willow.
Leaves unfolding in early spring, 6′—12′ long and ¼′—⅓′ wide; deciduous during the following winter. Flowers appearing in early summer in racemes or narrow panicles 3′—4′ long, and continuing to open for several months in succession, ¾′—1½′ long and ¾′—1¼′ across the expanded lobes of the corolla. Fruit ripening in the autumn, 7′—12′ long, ¼′ thick in the middle, persistent on the branches during the winter; seeds ⅓′ long and ⅛′ wide.
A tree, 20°—30° high, with a trunk usually more or less reclining, often hollow, and sometimes 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 ⅛′—¼′ 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 sapwood of 2 or 3 layers of annual growth.
Distribution. Banks of streams, and depressions in the desert, usually in dry gravelly porous soil; valley of the lower Rio Grande, and through western Texas, southern New Mexico, Arizona, southern Utah and Nevada to San Jacinto Valley, San Diego County, California; in northern Mexico and Lower California (Calamujuit).
Occasionally cultivated as an ornamental plant in the southern states, and in Mexico.