2366 



OPUNTIA 



OPUNTIA 



cles, and fewer spines. The fr. and fl. also show marked 

 differences. 



54. arborescens, Engelm. (O. stellata, Salm-Dyck). 

 Fig. 2608 (adapted from Pacific R. R. Report). An arbo- 

 rescent, numerously branched plant, 4-8 ft. high, with 

 trunk of larger plants having very rough, dark, unarmed 

 bark: joints with moderately prominent, narrow, cris- 

 tate tubercles, verticillate, horizontally spreading on 

 mostly pendulous, moderately spiny branches, mostly 

 3-6 in. long and 1 in. or less thick: areoles with dirty- 

 white wool and small yellow to light brown bristles; 

 spines 6-20, variable in length, 1 in. or less, central ones 

 more loosely sheathed, horny or reddish brown, white to 

 straw-colored sheaths: fls. purple, 2-3 in. wide: fr. 

 unarmed or with few spines, conspicuously tuberculate, 

 subglobose, 1 in. diam., yellow to yellowish red. S. W. 

 U. S. Frequently confused with O. imbricata and O. 

 spinosior, and intermediate between the two. Differs 

 from the latter in having much larger, more cristate 

 tubercles, fewer spines and different fr. 



55. spindsior, Tourney. A small tree, 6-12 ft. high, 

 with numerous verticillate branches, forming a rounded 

 head, the cylindrical trunk usually branching a few 

 feet above the ground, and with rough, dark brown or 

 grayish unarmed bark: joints verticillate and pendu- 

 lous, ultimate ones usually 4-8 in. long and about 1 in. 

 thick, dark green, frequently more or less purplish, with 

 short, crowded rhombic tubercles: areoles with white to 

 reddish brown wool and usually^ few, small, variously 

 colored bristles; spines 10-30, increasing in number 

 yearly as the joints become older until finally deciduous, 

 short, and rarely conspicuously sheathed, usually H~M 

 in. long: fls. showy, bright to dark purple, 2-2 J^ in. 

 wide, in whorls at the ends of the joints: fr. elliptical to 

 oblong, rarely obovate to globose, 1H~2J^ in. long, yel- 

 low, frequently remaining on the stems during the 

 second year. Ariz., N. Mex. 



56. Whipplei, Engelm. & Bigel. Fig. 2609 (adapted 

 from Pacific R. R. Report) . A spreading, sub-prostrate 

 shrub, rarely more than 2 ft. high, with numerous 

 ascending secondary branches, having short, crowded, 

 prominent tubercles: joints variable, terminal ones 

 clavate, 2-5 in. long and %-%in. thick, mostly 

 armed on upper half: areoles with short white wool 

 and a few short, light-colored bristles; spines white, 



Mex. This plant is frequently confused with 0. 

 spinosior, probably from confusion in the original 

 description. 



57. versicolor, Engelm. A small, numerously 

 branched tree, 6-10 ft. high, with rounded head and a 

 short trunk, having smooth, light brown or reddish 



2609. Opuntia Whipplei. 



very variable, on terminal joints, usually from 1-3 

 conspicuous loose-sheathed interior ones and several 

 small, deflexed or radiating ones: fls. greenish yellow, 

 crowded at the ends of the joints, 1-1)4 m - wide: 

 fr. unarmed or with few spines, pyriform to subglobose, 

 densely tuberculate, yellow or tinted with scarlet, 

 \4r\ in. diam., drying and remaining attached to 

 the plant during the winter. S. W. U. S. and N. W. 



2610. Opuntia ramosissima. 



brown, unarmed bark: joints much elongated, usually 

 6-12 in. long, sometimes 20, %-%in. thick, deep green, 

 more or less colored with red and purple: areoles with 

 short gray wool and lighter colored bristles; spines 

 variable, on terminal joints, usually from 5-13, older 

 joints with 10-20, rarely, however, increasing in num- 

 bers after the second year, reddish brown, with incon- 

 spicuous, close-fitting sheaths, %in. or less long: fls. 

 bronze-colored, 1-1 % in. wide: fr. pyriform to clavate. 

 of same color as joints, never yellow, sometimes tinged 

 with red or purple, unarmed or with a few persistent 

 short spines, 1-2 in. long. Ariz., N. Mex. 



58. tetracantha, Tourney. An irregularly branching 

 shrub, 2-5 ft. high, primary branches from a stout, 

 upright trunk 2-4 in. diam., and bearing numerous 

 short lateral ones at irregular intervals: joints very 

 variable in length, usually 4-10 in. long and ^in. thick: 

 areoles with whitish wool and a crescent-shaped tuft of 

 light brown bristles; spines 4, rarely more or less, 

 %-lJ^ in. long, stout, loosely sheathed, straw-colored, 

 flattened, strongly deflexed, not increasing in numbers 

 on older joints: fls. greenish purple, H-l in. broad: fr. 

 obovate to subglobose, Y^-\ in. long, juicy, scarlet, 

 unarmed, or with a few stiff deflexed spines. Ariz. 

 One of the most attractive of the cylindrical opuntias 

 on account of its numerous bright scarlet frs. 



59. arbuscula, Engelm. A short, numerously 

 branched, round-headed, arborescent plant, rarely 

 reaching the height of 5 ft., but always with an upright, 

 well-defined trunk, having rough, brown, unarmed 

 bark: joints usually 2-4 in. long and ^$in. wide, easily 

 broken from the plant: areoles comparatively large, 

 with white wool and brush-like tufts of long, slender, 

 yellow bristles; spines yellow, usually 1, frequently a 

 small, slender, additional one at either side, %-lK in- 

 long, loosely sheathed: fls. bronze-colored, %-l in. 

 wide: fr. unarmed, of same color as joints, long, clavate, 

 1-2 in. long and one-third as wide, mostly sterile, 

 fertile ones with a few remarkably large, irregular- 

 spheroidal seeds. Ariz., Sonora. 



60. leptoca&lis, DC. (O. frulescens, Engelm.). An 

 erect shrub, 2-4 ft. high, with long, slender, flexible 

 sts. branching from near the ground, and numerous 

 lateral secondary ones, very short, usually unarmed and 

 easily detached: joints about K~J4i n - thick: areoles 

 with short white wool and numerous reddish brown con- 

 spicuous bristles; spines usually 1, sometimes wanting, 

 erect, stout, frequently 2 in. long, brownish or horny, 

 with a loose yellow sheath: fls greenish yellow, ^j-M" 1 - 



