Zygia brevifolia Sudw.
Leaves 2′—3′ long, 2′ wide, with eight to ten 10—20-foliolate pinnæ and slender terete petioles 1′ in length and furnished near the middle with a dark oblong gland, when they unfold coated with pale tomentum and at maturity glabrous with the exception of the puberulous petiole and rachis; persistent or tardily deciduous; leaflets oblong-linear, obtuse or acute at apex, oblique at base, very short-petiolulate, light green on the upper surface, paler on the lower surface, ⅙′—¼′ long. Flowers white to violet-yellow, in globose or oblong heads ½′ in diameter, on thin pubescent peduncles bracteolate at apex, coated at first, like the flower-buds, with thick white tomentum, developed usually in pairs from the axils of lanceolate acute scarious deciduous bracts, and arranged in short terminal racemes; calyx shortly 5-lobed, puberulous on the outer surface, about 1/24′ long and one fourth the length of the puberulous petals persistent with the stamens at the base of the mature legume; stamens nearly ½′ long. Fruit ripening at midsummer and often persistent on the branches after opening until the trees flower the following year, straight, slightly torulose, short-stalked, contracted at apex into a short slender point, 4′—6′ long and ⅔′ wide, its valves thin, thick-margined, reddish brown on the outer surface, yellow tinged with red on the inner surface, reticulate-veined; seeds suspended by a slender coiled and somewhat dilated funicle, compressed, ovoid to nearly orbicular, dark chestnut-brown, very lustrous, ¼′ long, and faintly marked by large oval depressions; seed-coat thin, cartilaginous.
A tree, 25°—30° high, with a trunk rarely 5′—6′ in diameter, slender upright branches forming a narrow irregular head, and branchlets slightly striately angled, covered with minute white lenticels, light gray and puberulous when they first appear, becoming dark brown in their second year, and armed with stout rigid stipular spines sometimes ½′ long and persistent for many years; more often a shrub, sometimes only 2°—3° tall. Bark of the trunk smooth, light gray somewhat tinged with red, and often marked by large pale blotches. Wood dark-colored, hard, and heavy.
Distribution. Bluffs and bottom-lands of the lower Rio Grande, and on the upper Nueces River in Uvalde County, Texas; usually a low shrub spreading into broad clumps, but occasionally in the rich and comparatively moist soil of the banks of river-lagoons a slender tree; in Mexico more abundant, and of its largest size from the mouth of the Rio Grande to the Sierra Madre of Nuevo Leon.
3. [Pithecolobium flexicaule] Coult. Ebony.
Zygia flexicaulis Sudw.
Leaves persistent, 1½′—2′ long, 2½′—3′ wide, long-petiolate with slender puberulous petioles glandular near the middle and furnished at apex with small orbicular solitary glands, and 4—6 usually 6-foliolate pinnæ, the lowest pair often the shortest; leaflets oblong-ovate, rounded at apex, reticulate-veined, thin or subcoriaceous, glabrous, dark green and lustrous on the upper surface, paler on the lower surface, ¼′—⅓′ long; petiolules short and broad. Flowers light yellow or cream color, very fragrant, sessile in the axils of minute caducous bracts, appearing from June until August, in cylindric dense or interrupted spikes 1½′ long, on stout pubescent peduncles fascicled in the axils of the upper leaves of the previous year; corolla four or five times as long as the calyx and like it puberulous on the outer surface, and about as long as the tube formed by the union of the filaments; stamens ⅛′ long; ovary glabrous, sessile. Fruit ripening in the autumn and remaining on the branches until after the flowering season of the following year, sessile, tardily dehiscent, thick, straight or slightly falcate, oblique at base, rounded and contracted into a short broad point at apex, pubescent, 4′—6′ long and 1′—1¼′ wide, with thick woody valves lined with a thick pithy substance inclosing and separating the seeds; seeds suspended on a very short straight funicle, bright red-brown, ½′ long and ¼′ wide, irregularly obovoid, faintly marked by short oblong depressions; seed-coat thick, crustaceous.
A tree, 20°—30° high, with a straight trunk 2°—3° in diameter, separating 8°—10° from the ground into short spreading branches forming a wide round head, and stout zigzag branchlets, puberulous, light green or dark reddish brown when they first appear, becoming in their second year glabrous or rarely puberulous, dark reddish brown or light gray, and armed with the persistent stipular pale chestnut-brown spines ¼′—½′ long. Wood exceedingly heavy, hard, compact, close-grained, dark rich red-brown slightly tinged with purple, with thin clear bright yellow sapwood; almost indestructible in contact with the ground and largely used for fence-posts; valued by cabinet-makers and for fuel, and considered more valuable than that of any other tree of the lower Rio Grande valley. The seeds are palatable and nutritious, and are boiled when green or roasted when ripe by the Mexicans, who use their thick shells as a substitute for coffee.