CACTACEAE. 
39 
subinde erecto; flore flavo, ovario tubercula pulvilli-gera conferta sub-50 gerente; sepalis tubi 
sub-20 oblanceolatis cuspidatis, petalis sub-10 obovato spathulatis, obtusis mucronatis, stigmati- 
bus 8 patulis; bacca obovata tuberculosa profunde umbilicata. (Plate VI, figs. 1-3.) 
On both sides of the Colorado, from the San Francisco mountains to the headwaters Wil¬ 
liams’ river, sometimes called “Bill Williams’ fork,” and to the Mojave creek. The only erect, 
flat-jointed Opuntia in this section of country, 4-5 and sometimes even 7 feet high, forming 
large bushes, on one of which upwards of one hundred joints were counted. The large trunks 
have a scaly, grayish, or light-red brown bark; the pulvilli are not obliterated on it, as they 
are on 0. Engelmanni , but are largely developed, 4-6 lines in diameter, pulvinate, densely 
covered with a thick brown tomentum, surrounded by numberless straw-colored bristles, 4 lines 
in length, and bearing 20-30 or more yellow, compressed spines, often 1-2 inches in length, 
stellately radiating in every direction, and covering and shielding the whole surface of the stem. 
The only Opuntia which I find described as having a similarly armed stem is 0. Karwinskiana, 
Salm., which is said to have 18-20 gray spines on the oldest pulvilli. 
Joints 8-10 inches long by 6-8 wide, always of a very pale glaucous, or rather more yellowish 
green color, which is strikingly characteristic, even at a distance, and which has procured our 
name for the plant; pulvilli about 1 inch apart, strongly pulvinate; bristles two-fold and dis¬ 
tinct, the upper and outer, and by far the most numerous ones are shorter and thinner, and 
cover the upper semi-lunar area of the areola; inside of them is a semi-circular row of stouter 
and longer bristles, 4-6 lines long, which unite with the outer and shorter spines of the outer 
and lower margin of the areola. This arrangement is most distinct on the upper and more 
fully developed pulvilli; among our Opuntice it is only seen again, as far as known, in the 
obscure 0. dulcis from Presidio del Norte. Spines proper 1-1^ inches long, pale straw color, 
with faint transverse markings, hardly darker at base; shorter spines 4-9 lines long. 
The description of the flower was drawn from an old withered specimen gathered in winter; 
it seems pale yellow, between 2 and 3 inches in diameter; sepals and petals remarkably narrow, 
the latter about 1 inch long, and not half as wide. The ovary and fruit (all the specimens 
found were sterile) are quite tuberculous ; pulvilli crowded, bearing brown wool and short, 
yellow bristles. Specimens of sterile fruit seen 1|--1| inches long. 
5. Op. procumbens, (sp. nov.): prostrata, articulis orbiculato-obovatis grandibus pallide viridi- 
bus, pulvillis remotissimus griseo-tomentosis, setis flavis robustis valde inmqualibus, aculeis 
validis 2-4 subinde (in articulis vetustioribus ?) 7-9 compressis angulatis imequalibus, strami- 
neis s. pallidioribus versus basin obscurioribus, smpe rufis fuscisve, deflexis. (Plate VII, 
figs. 4-5.) 
From the San Francisco mountains to the Cactus Pass, at the head of Williams’ river, in 
rocky localities. Joints 9-13 inches long, 7-9 broad, prostrate, always on edge; pulvilli 11,-2 
inches apart; bristles 2-4 lines long, comparatively stout; spines 1-2 inches long; no flower or 
fruit seen. Very similar to 0. Engelmanni; but prostrate, with even more distinct pulvilli, and 
stouter and often more numerous spines. 
6. Op. angustata, E. & B.: prostrata s. adscendens, articulis elongato-obovatis versus basin 
•sensim angustatis suberectis; pulvillis remotis griseo-tomentosis, setis fulvis gracilibus; aculeis 
paucis (2-3) validis compressis albidis s. stramineis, versus basin rufis s. fulvis, adjectis smpe 
infra 1-2 debilioribus omnibus deflexis; bacca obovata, tuberculata rubella, late profundeque 
umbilicata pulvillis 24 stipata seminibus magnis subregularibus late marginatis. (Plate VII, 
figs. 3-4.) 
From'the foot of the Inscription rock, near Zuni, to Williams’ river, and westward as far as 
the Cajon Pass of the California mountains. Prostrate in the first and last-mentioned localities, 
but sub-erect in the bottoms of Williams’ river. Joints 6-10 inches long, and at the upper 
third 3-4 inches wide, gradually narrowed downwards, rounded above; puluilli over 1 inch 
