A452 
choff of 1871; Lemmon 305; Palmer 800; Rothrock 101, 584; Pringle of 
1881; Vasey of 1831; Palmer of 1890, It. Huachuca; Nealley of 1891, 
Silver City; Wileox of 1894, Ft. Huachuca; Dr. Loew, Chloride): 
SONORA (Thurber 336): CoamuiLa (Palmer 377 of 1880): also cult. 
in Mo. Bot. Gard, 1862, growing in 1893, 
A Mexican species of wide range and extending northward to the plains of Colorado, 
covering extensive tracts. Nealley’s specimens, from Silver City, Arizona, have 
shorter perpendicular and suberect central spines, shorter than the radials, Vasey’s 
from 1 Paso have tubercles 25 to 30mm, long, which so separate the bunches of 
spines that the joints have not their usual spiny appearance. Palmer 377 from 
Coahuila was distributed as imbricata, and I doubt not that much Mexican arbores- 
cens has been mistaken for that species, The 1 or 2 white spines of imbricata,as well 
as its clavate joints, should easily distinguish it from arborescens, although it is 
very doubtful whether it deserves specific separation. 
89. Opuntia imbricata (Haw.) DC. Prodr. iii, 471 (1828). 
Cereus imbricatus Haw. Rev. 70 (1812). 
An irregular branching shrub 9 to 15 dm. high, with trunk often 7.5 
em. in diameter, branching above, solitary or forming thickets: joints 
more or less clavate, with prominent compressed-cristate tubercles, and 
elongated subulate leaves: pulvini with straw-colored wool: spines 1 
or 2, white, setaceous or rigid, sheathed: flowers rose-colored, crowded 
near the summit of late branches: fruit depressed-globose, umbilicate : 
seed thick, irregular, 3 to 3.5 mm. in diameter. (1. Cact. Mex. Bound. 
t. 73, f. 7,8)—Type unknown. 
From Coahuila and San Luis Potosi to southern Mexico. 
Specimens examined: COAHUILA (Palmer 370 of 1880; Parry & 
Palmer 281): STATE OF MEXICO (Gregg 568, 677, 684, 685 of 1849): 
ZACUALCO (Bourgeau 264 of 1865-66): Mexico, with no state indicated 
(Wright of 1847): also cult. Gard. Montpel. 1126. 
Very closely related to arborescens, and possibly only a small sparsely armed form 
of it, but in the absence of type material or even complete material it is for the 
present kept separate. 
90, Opuntia versicolor Mngelm. MSS. 
Arborescent, with spineless trunk 5 to 7.5 em, in diameter, irregu- 
larly much branched: joints cylindrical, 12 to 18 em. long or more, about 
1,5 em, in diameter, with linear rather prominent tubercles (when young) 
1 to 2.5 em. long, soon flattening and disappearing on older branches, 
and round-ovate cuspidate leaves: pulvini with short gray wool, and 
usually a small cluster of bristles at upper edge: spines 4 to 13 on 
young joints, 15 to 20 on older ones, stellate, reddish-brown, with 
straw-colored sheaths (close and soon disappearing), the inner 1 to 4 
usually detlexed and unequal (6 to 13 min.), the radials shorter: flowers 
yellow, 2 to 2.5m, broad: fruit becoming clavate, 2 to 2.5 em. long, at 
length reddish or yellowish and apparently dry: seeds irregular, angu- 
lar, about 5mm. broad, with narrow commissure.—Type, specimens of 
Parry, Pringle, G. Engelmann, and Miller, in Werb. Mo. Bot. Gard. 
