210 CACTACEH OF THE BOUNDARY. 
Subgen. 3. CYLINDROPUNTIA. [53] 
Articuli teretes, clavati seu cylindrici. Aculei plerumque vaginati. 
Flores parvi seu majores, Petala obovata seu orbiculata, rubra seu purpurea, rarius flava. 
Bacca umbilicata, sicca seu subsicca, rarissime pulposa ; inermis, seu setosa, seu aculeata; floris rndimentis 
dejectis seu persistentibus. 
Semina-sutura commissurali cincta, plerumque immarginata. 
Embryo circa albumen copiosius subcircularis- Cotyledones contrari#, incumbentes, haud raro oblique, 
interdum parallela, accumbentes. 
The species forming this subgenus have an appearance so striking, and at the same time so distinct from the 
common type of Opuntia, that a generic separation has been attempted ; but the flowers are so entirely identical, and 
in the fruit so little difference is observed, that it had to be abandoned. The only real distinction, and a permanent 
one as far as my observation goes, I find in the embryo. In Cylindropuntia it is less curved, not completing an entire 
circle, and surrounds a more copious albumen ; in Platopuntia, on the contrary, it is somewhat spirally coiled, and the 
space for the albumen is thereby much smaller. It is worthy of remark that in Cylindropuntia the direction of the 
cotyledons is by far less constant than in other Cactaceew ; though usually incumbent, as in all other Opuntie, they are 
very often oblique, and not rarely accumbent, like those of Echinocactus. In O. echinocarpa I have found them 
invariably so. 
§ 1. Clavate. 
Stems prostrate ; joints short and clavate, tuberculate, proliferous near the base; the ligneous tissue loosely 
reticulated, much like that of Platopuntia; spines more or less compressed and striate, the epidermis not or but 
slightly separating from them; flowers yellow and rather large; fruit always dry, crowned by the persistent remains 
of the flower, beset on the pulvilli with numberless spiny bristles. 
12.. O. Parry, E. in Sillim. Journ. Dr. Parry observed this species on the eastern slope of the California 
mountains near San Felipe, and sent notes about it, an extract of which I published in Silliman’s Journal. Since then 
Dr. Bigelow has collected it eighty or one hundred miles northeast of that place, near the Mojave River, and in his 
report a full account of the plant is given. Dr. Parry describes the joints as 4-8 inches long, ascending, with white 
es oe 6 lines long ; flowers greenish-yellow, 1} inch in diameter ; stigmata green. 
O. Emoryi, sp. nov. : prostrata ; articulis cylindricis basi clavatis glaucis adscendentibus ; tuberculis — 
gatis ; Se magnis se aucas rigidas gerentibus ; aculeis plurimis rufis seu fuscis demum cinerascentibus 
interioribus 5-9 validioribus didatigtlaitin compressis porrectis seu deflexis, superioribus solum suberectis ; cralebe 
exterioribus 10-20 szpe pluriserialibus undique radiantibus, superioribus gracilioribus teretiusculis, inferioribus 
rigidioribus compressis ; floribus flavis extus rubellis; bacca ovata basi clavata flava pulvillis 35-50 setosissimis, stipata 
omnibus seu solum inferioribus aculeatis ; seminibus numerosissimis valde inequalibus plerumque transversis indis- 
XI 
Arid soil south and west of El Paso, especially between the Sand-hills and Lake Santa Maria (Wright, Bigelow), 
in Sonora (Wright), and on the lower (tila and in the Colorado desert (Schott). Flowers in August and Sep- 
tember. — This is the largest and stoutest of our clavate Opuntie, with very numerous and long spines, spreading [54] 
largely, and growing 6-12 inches high, — forming a welcome retreat for the smaller Rodentia, snakes, etc., which, 
under the protection of its powerful spines, are secure against the attacks of their enemies. Joints curved, 4-6 inches 
long, 1-1} inch in diameter. The tubercles are 1-14 inch long, very prominent, and might be termed cylindric if 
they were not longitudinally attached to the stems. The upper tubercles of each joint and their spines are more fully 
developed than the others in this, as in all Opuntie. In those we distinguish 4 larger central spines ; the upper one 
more erect, the lower one elope longer, broader, and deflexed. We often find a second upper one above, and a 
second lower one below the other; or the 4 central spines are surrounded by a circle of 6 or 8 somewhat smaller 
spines, which may be shectens an interior series of radiating ones ; the exterior series consists of 10-20 shorter 
and more slender spines. But the arrangement of spines in this genus is never so regular as it is in other genera, 
especially in Echinocactus. Stoutest spines 1}-2} inches in length, 3-1 line wide, striated, flat on the upper, strongly 
carinate on the lower surface, so as to appear triangular ; other interior spines 1-2 inches, exterior ones 3-14 inch long. 
Fruit 2-24 inches long, an inch in diameter ; er pulvilli 2-23 lines in diameter ; bristles whitish or reddish, 
3-4 lines long ; ; 10 or 12 spines, 4-8 lines in length, are mixed with the bristles on all or only on the lower pulvilli. 
Seeds, very t in size and shape, in the same fruit, 21-3 lines in diameter or more, often transverse or an 
— or beaked ; cotyledons generally oblique, sometimes accumbent, contrary to the usual arrangement in this genus. 
The i from the lower Gila and the Colorado must, I have little doubt, also be referred here. Plant 
re inches high, far-spreading, of a dull grayish-green color; joints similar to those described above ; spines only 
