Distribution. River valleys in fertile soil, or as a shrub on dry barren ridges; valleys of the upper Marcos and of the Guadalupe Rivers, Texas, to the Rio Grande; often extremely common on the bottom-lands, and probably of its largest size in the United States on the Guadalupe and Nueces Rivers sixty or seventy miles from the coast; through Nuevo Leon and Coahuila to the mountains of San Luis Potosí.
Often planted as a shade-tree in the streets of the cities and towns of western Texas and northeastern Mexico.
LXII. VERBENACEÆ.
Trees or shrubs, with opposite simple entire persistent leaves, without stipules. Flowers perfect; calyx 5-toothed or parted, persistent under the fruit; corolla 4 or 5-lobed, the lobes imbricated in the bud; stamens 4, inserted on the tube of the corolla in pairs of different lengths, anthers 2-celled, introrse, the cells opening longitudinally; ovary sessile on the annular disk; style simple, 2-lobed and stigmatic at apex. Fruit a fleshy drupe or a capsule.
The Verbena family with seventy-eight genera, largely composed of herbaceous plants, is widely scattered through temperate and tropical regions. Some of the species are important timber-trees, the most valuable being the Teak, Tectoria grandis L. f., of southeastern Asia and the Malay Archipelago, and some of the tropical species of Vitex.
CONSPECTUS OF THE ARBORESCENT GENERA OF THE UNITED STATES.
Flowers in axillary or terminal racemes; staminodium 1; ovary imperfectly 4-celled; fruit a fleshy drupe.1. [Citharexylon.] Flowers cymose in pedunculate spikes or heads; staminodium 0; ovary 1-celled; fruit a capsule.2. [Avicennia.]
1. CITHAREXYLON L.
Trees or shrubs, with coriaceous lustrous leaves, slightly angled branchlets, without a terminal bud, and with minute axillary buds. Flowers small, on short ebracteolate pedicels, alternate or scattered on the filiform rachis of a slender raceme; calyx membranaceous, tubular-campanulate, truncate, minutely 5-toothed, spreading and cup-shaped under the fruit; corolla salver-form, usually white, the spreading limb somewhat oblique, 5-lobed, the lobes broad-ovate, rounded, slightly unequal, the 2 posterior exterior, sometimes reduced to staminodia; stamens included; filaments short, filiform, slightly thickened at base, the 2 anterior filaments longer than the others; anthers oblong; staminodium 1, posterior, linear, acute, rarely fertile; ovary ovoid, incompletely 4-celled by the development of two parietal placentas, gradually narrowed into a short included style; ovule solitary in each cell, erect, attached laterally near the base, ascending, anatropous; micropyle inferior. Fruit a 2-stoned 4-seeded fleshy drupe tipped with the remnants of the style, with thin flesh and a thick-walled bony stone separable into 2 2-seeded compressed smooth light brown nutlets rounded on the back and concave on the inner face. Seed erect, without albumen, filling the seminal cavity; seed-coat membranaceous, light brown; embryo subterete, straight; cotyledons thick and fleshy, oblong, much longer than the short inferior radicle turned toward the oblong basal hilum.
Citharexylon with about twenty species is confined to tropical America, where it is distributed from southern Florida through the West Indies to southern Mexico, Lower California, Bolivia, and Brazil.