172 CACTACEZ OF WHIPPLE’S EXPEDITION. 
who, by his zealous and liberal co-operation, afforded every facility in his power in the various collections of natural 
history. (Plate XVII. figs. 5-6, and Plate XVIII. fig. 4.) 
23. O. ARBORESCENS, Engelm. Found first 200 miles east of the Pecos, and from there abundantly as far west 
as Zui, where other cylindric Opuntie take its place. In this region it does not grow higher than 5-8 feet, and can 
scarcely be called arborescent. It is always well characterized by the verticillate often somewhat pendulous branches, 
the cristate-tuberculate spineless fruit, and the smooth seeds with a distinct and broadly linear commissure. Seeds of 
specimens collected at Zuni smaller than others, only 14 line in diameter. 
24. O. ACANTHOC » sp. n aule arborescente erecto reticulato-lignoso, ramis adscendentibus divaricatis 
articulis eylindricis oa pallid rinse, orn oblongo-linearibus sa ovato-orbiculatis breviter 
tomentosis vix setosis, aculeis numerosis s, plurim 25) stramineo-vaginatis undique porrectis, stellatis; bacca 
subglobosa late nr tuberculata ; pulvillis a tomentosis parce setosis saat validis 8-10 snndilies 
seminibus ae multangulis late commissuratis. (Plate XVIII. figs. 1-3.) 
the untains of Cactus Pass, about 500 miles west of Santa Fé. Stout; stem 5-6 feet high, wood forming 
a hollow aie tube, solid at base ; branches few, never verticillate, separating at acute angles. Joints 4-6 inches 
long, 1 inch in diameter ; tubercles 9-10 lines long ; pulvilli, in some with 1 central and 6 or 8 exterior spines, in 
others with 3-7 interior and 10-20 exterior stallateby radiating spines. Central spines 1-1} inch, exterior 4-10 lines 
long, with a yellowish or brownish sheath. Fruit 1 inch long, with a large but not deep nbehcem a nd 12-15 rather 
shallow tubercles ; spines of fruit stout, 3-6 lines long, stouter and more crowded toward the top of the fruit. Seeds 
pie any other of our Opuntiz, 24-3 lines in diameter, with rather ng ucrapeani often spongy on the margin, 
on the sides with many even or concave faces separated by sharp ri 
This peculiar species cannot be confounded with any other, Sir comes, in the arrangement of spines, [52] 
nearest to O. arborescens, from which it is easily distinguished by its manner of growth, its elongated tubercles, 
and especially the much less tuberculated and spiny fruit and the peculiar seed. 
25, O. TesseLaTaA, Engelm.: caule frutescente erecto s. diffuso, dense lignoso, ramosissimo, ramis divaricatis, 
articulis gracilibus teretibus, plano-tuberculatis casiis, tuberculis 5-6 angulatis confertissimis depressis, planiusculis ; 
pulvillo lineari tomentoso vix setis paucis deciduis instructo, inermi s. medio s. versus basin aculeo elongato porrecto 
s. subdeflexo albido flavido s. fulvo vagina laxi basi constricta flava s. e flavo fulva indusiato, singulo s. rarissime binis ; 
-aculeis paucis brevibus setaceis infra seepe adjectis ; floris purpurei ovario obovato s. clavato pulvillis 30-50 villoso- 
tomentosis inermibus s. parce aculeolatis dense stipato ; sepalis tubi sub-8 obovato-orbiculatis cuspidatis petalis 5 late 
obovato-orbiculatis emarginatis ; filamentis exterioribus latioribus persistentibus, stigmatibus revibus ovatis — 
ad is ; bacca ovata basi apiceque contracta sicca pulvillis villosis wala: latissimis confertissimis stipata, floris 
rudimentis coronata ; seminibus subregularibus margine spongioso crasso parum prominente cinctis. O. ramosissima, 
E. in cate Journ, November, 1852. (Plate XXI. figs. 1-7.) 
of the lower Colorado, and from thence to the California mountains. First discovered by Dr. Parry in 
the Colorado desert ; afterwards found by Dr. Bigelow from the valley of Williams’s River to 70 miles east of 
Cajon Pass, in the California mountains. The flower was first noticed by Mr. A. Schott, in western Sonora, toward 
the lower Colorado. Flowers May to September. Stems 2-6 feet high, mostly branching from the base below, 
1-3 inches in diameter, covered with a dark-gray scaly bark ; wood of young branches reticulate, very soon becoming 
solid, but even then the reticulated structure remains visible in the different layers of wood. Annual layers not as 
distinct as the medullary rays, but more so than in 0. frutescens; in a stem of near 2 inches diameter we counted 
35 annual layers, 8 or 9 of which belong to the alburnum. Branches numerous and slender, of an ashy or grayish- 
green color ; younger ones 3 or 3} lines in diameter, well diedetan by the remarkable flattened tubercles, which, 
by closely crowding together, become 5 or 6 angular, diamond-shaped. The areola is linear, extending down to the 
geet on “si tubercle ; its short tomentum usually — upwards between the next adjoining tubercles. Tubercles 
small bristly spines at the base of the pulvillus, 2-3 sometimes even 5 in number, 1-4 lines long. Flower purple, 
about 6 lines in diameter, lowest part of the tube naked. Fruit 9-10 lines long, resembling much the fruit of the 
te Opu shape, being contracted above, with a narrow and deep umbilicus, and retaining the dead remains 
of the flower, of eka the cad, scale-like exterior filaments are most conspicuous ; pulvilli large yee woolly, almost 
entirely covering the fruit, and beset with 30 to 50 reddish-brown, bristly, flexuous spines, 2-3 lines long. Seeds few, 
oe nearly or quite 2 lines in diameter. 
O. vaarnata, Engelm.: caule frutescente erecto dense lignoso, ramis virgatis demum teretibus junioribus 
égihceas oblongo-elongata. subprominentia gerentibus lete viridibus ; foliis subulatis pulvillis orbiculatis magnis 
in 
