0001 ۰ 53 
About Albuquerque, where Dr. Wislizenus had already collected it in 1846; apparently 
extending into Mexico, as Dr. Gregg collected what seems to be the same species about San 
Luis Potosi. Shrub 3-5 feet high; lower part of stem 1-1} inch thick, covered with scaly, 
light-yellowish-brown bark ; older branches smooth terete, younger ones 3-4 lines in diameter, 
strongly tuberculated; tubercles 6-9 lines long; leaves slender, about 3 lines long, and appa- 
rently somewhat persistent, as they are sometimes found adhering, though withered, even to 
fruit-bearing branches, which, of course, are over a year old. The same, though to a less extent, 
is sometimes seen in O. frutescens. Pulvilli unusually large; bristles in the young ones form- 
ing a small but distinct bunch at the upper edge of the areola, but disappearing on the older 
joints, contrary to the usual occurrence, when the bristles become stouter and more numerous 
in older joints. Spines 1-2} inches long, dark, with very loose and glistening sheaths; second 
or smaller spine sometimes lateral, but usually above the principal one, not below it, as in most 
others. Flower unknown. Fruit ovate, 8 or 9 lines long, the pulvilli often bear 2-5 obtuse 
bodies, almost hidden in the tomentum, apparently glandular, but of a fibrous structure. Seeds, 
12-15 in each fruit, about 2 lines or a little more in diameter, commissure broad, prominent, 
forming a distinct, somewhat spongy, rim. (See plate XX, fig. 1, and plate XXIV, figs. 13- 
15.) In Dr. Wislizenus' report, the long-spined form of O. frutescens was confounded with this 
species. It is possible, however, that O. vaginata, as described here, may be a stouter, tuber- 
culated form of O. frutescens, with lighter colored, tuberculated fruit, and larger seed. 
27. O. FRUTESCENS, Engelm. This well known species was observed from Laguna Colorado, 
60 miles east of the Pecos, to Williams’ river, a branch of the great Colorado, always with the 
same characters. The bark is scaly, almost papery, with a silvery reflection ; the wood shows 
the medullary rays very distinctly, especially 5 of them; much less the annual layers. Fruit 
deep scarlet, smooth, small, sometimes almost obliterated pulvilli, 5-9 lines long ; seeds 5-10, 
about 14 lines in diameter, with a narrow and often acute margin. The forms collected on the 
expedition belong to var. a. longispina; the var. ۵. brevispina has been observed only in Texas 
and northeastern Mexico. (See Plate XX, fig. 2-5, and Plate XXIV, fig. 16-19.) 
