LEGUMINOSE. SILVA OF.NORTH AMERICA. 43 
ROBINIA NEO-MEXICANA. 
Locust. 
FLowers pale rose-colored, in short crowded glandular-hispid racemes. Legume 
glandular-hispid. Branches naked. 
Robinia Neo-Mexicana, Gray, Mem. Am. Acad. n. ser. 491.— Watson, King’s Rep. v. 419.— Sargent, Forest 
v. 314 (Pl. Thurber.). —Torrey, Pacific R. R. Rep. iv. Trees N. Am. 10th Census U. S. ix. 56. — Coulter, Man. 
79; Bot. Mex. Bound. Surv. 53.— Walpers, Ann. iv. Rocky Mt. Bot. 59. 
A small tree, sometimes twenty or twenty-five feet in height, with a slender trunk six or eight 
inches in diameter; or more often a low shrub. The bark of the trunk is thin, slightly furrowed, and 
hight brown, the surface separating into small plate-like scales. The branchlets when they appear are 
pale and coated with rusty brown glandular hairs which increase in length during the summer and do 
not disappear until the autumn. In winter the branchlets of the previous season are slightly puberulous, 
bright reddish brown, often covered with a glaucous bloom, and marked by a few scattered small pale 
lenticels. The winter-buds are minute, depressed-globular, and protected by a scale-like covering coated 
with dark brown tomentum. The leaves vary from six to twelve inches in length, and are composed of 
from fifteen to twenty-one leaflets borne on a stout pubescent petiole grooved on the upper side and 
enlarged at the base. The leaflets are elliptical-oblong, mucronate, rounded, or sometimes slightly 
emarginate at the apex, usually wedge-shaped or sometimes rounded at the base, an inch and a half 
long and an inch broad; at first they are coated on the lower surface and the margins with soft brown 
hairs, and on the upper surface with silvery white pubescence ; and at maturity they are thin, pale blue- 
green, conspicuously reticulate-veined, with slender midribs and primary veins, and quite glabrous with 
the exception of the lower side of the midribs and the stout petiolules, which are slightly puberulous. 
The stipules are chartaceous when they appear, and are covered with long silky brown hairs, which 
also form a tuft at their apex; at maturity they become stout slightly recurved flat brown or bright 
red spines sometimes an inch or more in length.’ The stipels are membranaceous, a quarter of an inch 
long, often recurved, and sometimes do not disappear until the end of the season. The flowers, which 
are an inch in length, appear in May in short compact many-flowered glandular-hispid racemes with 
stout peduncles. The pedicels are slender, half an inch long, and, like the exterior of the calyx, 
DBD? 
covered with stout glandular hairs. The corolla is pale rose-colored or sometimes almost white, with a 
broad standard and wing-petals. The legume is three or four inches long with a narrow wing, and is 
covered with stout glandular hairs and conspicuously tipped with the remnants of the recurved style. 
The seeds are very dark brown, slightly mottled, and a sixteenth of an inch or rather more in length. 
Robinia Neo-Mexicana inhabits the banks of mountain streams from the valley of the Purgatory 
River in Colorado, through northern New Mexico to the Santa Catalina and the Santa Rita Mountains 
in Arizona, where it occurs at elevations varying from four thousand to seven thousand feet above the 
sea-level, and to southern Utah, where it has been found near Kanah and in Mt. Zion Canon of the 
west fork of the Rio Virgen. Only in the valley of the Purgatory River near Trinidad in Colorado is 
it known to grow into a small tree. 
The wood of Robinia Nceo-Aexicana is heavy, exceedingly hard, strong, and close-grained, with a 
satiny surface; it contains many evenly distributed open ducts and thin conspicuous medullary rays. 
1 The stipular spines of this species, which inhabits an arid re- and are usually well armed against them, are more constantly devel- 
gion where plants require special protection from browsing animals oped and generally much larger than those of the other Robinias. 
