LEGUMINOS. SILVA OF NORTH AMERICA. 135 
PITHECOLOBIUM BREVIFOLIUM. 
Huajillo. 
FLowers perfect, in globose heads. Legume flat, straight, the valves not contorted 
after opening. Branches armed with rigid spinescent stipules. 
Pithecolobium brevifolium, Bentham; Gray, Smithsonian ley, Bot. Biol. Am. Cent. i. 359. —C. G. Pringle, Garden 
Contrib. iii. 67 (Pl. Wright. i.) ; Trans. Linn. Soe. iii. and Forest, ii. 393.— Sargent, Garden and Forest, ii. 
592 (Rev. Mim.).— Torrey, Bot. Mex. Bound. Surv. 400. — Coulter, Contrib. U. S. Nat. Herb. ii. 101 (Man. 
62.— Havard, Proc. U. S. Nat. Mus. viii. 500. — Hems- Pl. W. Texas). 
A tree, twenty-five or thirty feet in height, with a trunk rarely five or six inches in diameter and 
slender upright-growing branches which form a narrow irregular head ; or more often a shrub sometimes 
only two or three feet in height. The bark of the trunk is smooth, light gray somewhat tinged with red, 
and often marked with large pale blotches. The branches are armed with stout rigid stipular spines 
sometimes half an inch long and persistent for many years; the branchlets are slightly striately angled 
and covered with minute white lenticels ; when they first appear they are light gray and puberulous, and 
in their second year dark brown. The leaves are persistent or tardily deciduous, long-petiolate, two or 
three inches in length, two inches in breadth, and with eight to twelve pinne; when they unfold they 
are coated with pale tomentum, but at maturity are glabrous with the exception of a faint pubescence 
covering the petioles and rachises. The petioles are slender, terete, an inch long, and furnished near 
the middle with a dark oblong gland. The leaflets are in ten to twenty pairs and are oblong, linear, 
obtuse or acute at the apex, oblique at the base by the greater development of one of the sides, very 
short-petiolulate, from a sixth to a quarter of an inch in length, light green on the upper, and paler on 
the lower surface. The flowers are collected in globose or oblong heads half an inch in diameter and 
borne on thin pubescent peduncles which, when they first appear, are coated like the flower-buds with 
thick white tomentum; they are bracteolate at the apex, and are developed from the axils of lanceo- 
late acute scarious deciduous bracts, and arranged in short racemes on the ends of the branches. 
The flowers are white or pale yellow, and when the stamens are fully grown are nearly half an inch 
long. The calyx is shortly five-lobed, puberulous on the outer surface, and about a twenty-fourth of 
an inch long or one quarter the length of the petals, which are puberulous on both surfaces, and, with 
the stamens, are persistent at the base of the fully grown fruit. The legumes, which ripen in mid- 
summer and often remain on the branches after opening until the trees flower the following year, are 
straight, compressed, slightly torulose, short-stalked, contracted at the apex into a short slender point, 
four to six inches long and two thirds of an inch broad. Their valves are somewhat membranaceous, 
thick-margined, reddish brown on the outer, and yellow tinged with red on the inner surface, and 
reticulate-veined. The seeds are suspended transversely by slender coiled and somewhat dilated funi- 
cles, and are compressed, ovate, or nearly orbicular and a quarter of an inch long; the testa is thin, 
dark chestnut-brown, very lustrous, and faintly marked on the two sides of the seed with large oval 
depressions. 
Pithecolobium brevifolium is scattered in Texas along the bluffs and on the bottom-lands of the 
lower Rio Grande, occurring only at a few places between Rio Grande City and the mouth of the river. 
In Texas it is usually a low shrub spreading into broad clumps, but occasionally, in the rich and com- 
paratively moist soil of the river lagoons, a slender straggling tree. In Mexico, from the mouth of the 
Rio Grande to the Sierra Madre, it is much more common. Here it grows to its largest size and, with 
