OP0NTIA 



OPUNTIA 



1151 



in diain., having a thick, grayish, scaly, unarmed barli: 

 joints congested toward the ends of the larger branches, 

 ovate to ovate-cylindrical, 2-8 in. long and often 2 in. 

 thick, very fragile and tumid, easily becoming detached 

 and taking root, bluish green, somewhat glaucous : areo- 

 he with white wool and bright straw-colored bristles; 

 .spines on young growth 5-8, increasing yearly until 

 ultiiiKitely 30-50, finally deciduous, with loose, glisten- 

 i]ii;. white or .straw-colored sheaths IK in. or less long: 

 lis. '4-I in. wide, pink : fr. obovate to globose, light 

 grueii. pendulous, in large, proliferous clusters, some- 

 times 50 in a single cluster. Southwestern U. S. and 

 North Mexico. — The common "Cholla" of the Arizona 

 jiluins. where it tiftt-n become.s a fair-sized tree and nota- 

 lih' for its fiiniiichilili' armor of barbed spines completely 

 hidiui; till' suitMi-c of the plant. 



Viir. mamillata, Coult. Differs in having fewer, 

 shorter spines. 



52. Bigeldvii, Engelm. An erect, compact plant, 4-6 ft. 

 high, rarely higher, with fragile woody skeleton which 

 does not appear in .joints of the first year's growth, the 

 most densely spine-covered and difficult to handle of 

 the cyliiuirical Ujnmtias : joints readily detached and 

 f.irniiiii; furniidulile burs, ovate, short elliptical to long 

 and cylinclriiMl. with ri'uiiiled ends, readily breaking 

 from tlie plant and taking root, pale green, fragile, tu- 

 mid, terminal iines freqm-ntly 3-5 in. long and half as 

 thick: areolae close together, with white wool and pale 

 yellow bristles ; spines 10-20, .some very small, increas- 

 ing in number as stems become older, straw-colored, 

 loose-sheathed, 1 in. or less long, completely hiding the 

 .surface of the plant; fis. greenish red, I in. broad: fr. 

 very spiny, ovate, l'4'-2 in. long and one-third as wide, 

 few-seeded, mostly sterile. Ariz., Calif. 



5.1. imhricita, P. DC. A wide-spreading, irregularly 

 branidiing sliruli, rarely more than 5 ft. high, the trunk 

 and larger branches with dark, rough, unarmed bark: 

 joints frequently 12 or 14 in. long and I-IH in. thick, 

 with very prominent long, cristate tubercles : areolae 

 with yellowish wool and straw-colored bristles; spines 

 2-5, of variable length, 1 in. or less long, loosely 

 sheathed, white to straw-colored: fls. 2-2 J4 in. wide, 

 light purple : fr. unarmed, depressed globose, with large 

 tubercles, yellow, 1-1^^ in. in diam., adhering to the 

 plant and drying on the stems during the winter. Tex. 

 and northern Mex. — Usually confused with O. arbores- 

 cens, from which it differs in its smaller growth, differ- 

 ent habit, much longer joints, larger, more prominent 

 tubercles, and fewer spines. The fruit and flower also 

 show marked differences. 



51, arborSscens, Engelm. (0.s?e??iifa,Salm.). Anarbor- 

 isreut. nuiiieriiusly branched plant, 4-8 ft. high, with 

 trunk nf larger plants having very rough, dark, unarmed 

 bark: joints with moderately prominent, narrow, cristate 

 tubercles, verticillate, horizontally spreading on mostly 

 pendulous, moderately spiny branches, mostly 3-6 in. 

 itjug and ] in. or less thick : areola with dirty-white 

 wool and small yellow to light brown bristles; spines 

 6-20. vuri:tl>le in length. I in. or less, central ones more 

 loosely shoatlieil, horny or rcdilish brown, white to 

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

 unarmed or with few spines, conspicuously tuberculate, 

 subglobose, 1 in. in diam., yellow^ to yellowish red. 

 Southwest U. S. — Frequently confused with O. uiihri- 

 cata and O, spinosior, intermediate between the two. 

 Differs from the latter in having much larger, more 

 cristate tubercles, fewer spines and different fruit. 



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

 with numerous verticillate branches, forming a rounded 

 head, the cylindrical trunk tisually branching a few 

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

 grayish unarmed bark : joints verticillate and pendulous, 

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

 dark green, frequently more or less purplish, with 

 short, crowded rhombic tubercles: areolae with white to 

 reddish brown wool and tisually few, small, variously 

 colored bristles; spines 10-30, increasing in number 

 yearly as the joints become older until finally deciduous, 

 short, and rarely conspicuottsly sheathed, usually }4-% 

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

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

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



low, frequently remaining on the stems during the sec- 

 ond year. Ariz., northern Mex. 



56. Whipplei, Engelm. and Bigel. A spreading, sub- 

 prostrate shrub, rarely exceeding 2 ft. in height, with 

 numerous ascending secondary branches, having short, 

 crowded, prominent tubercles: joints variable, terminal 

 ones clavate, 2-5 in. long and -:i--'4 in. thicli. mostly 

 armed on upper half: areola' with short white wool and 

 a few short, light-colored bristh's; sjoTies white, very 

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

 spicuous loose - sheathed interior ones and several 

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

 crowded at the ends of the joints, 1-1^4 in. wide; fr. 

 unarmed or with few spines, pyriform to subglobose, 

 densely tuberculate, yellow or tinted with scarlet, K-1 

 in. in diam., drying and remaining attached to the plant 

 during the winter. Southwest U. S. and northwest Mex. 

 — This plant is frequently confused with O. Hpinosior, 

 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 brown, unarmed 

 bark : joints much elongated, usually 6-12 in. long, some- 

 times 20, %-% in. thick, deep green, more or less colored 

 with red and purple : areolae 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 numbers after the second year, 

 reddish brown, with inconspicuous, close-fitting sheaths, 

 iJ4 in. or less long; fls. bronze-colored, I-IJ4 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., northern Mex. 



58. tetrao&ntha, Toumey. An irregularly branching 

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

 right trunk 2—4 in. in diam., and bearing numerous 

 short lateral ones at irregular intervals : joints very 

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

 areoljB with whitish wool and a crescent-shaped tuft of 

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

 1% in. long, stout, loosely sheathed, straw-colored, 

 flattened, strongly deflexed, not increasing in numbers 

 on older joints: fls. greenish purple, J4-1 in. broad: fr. 

 obovate to stibglobose, J^-1 in. long, juicy, scarlet, un- 

 armed, or with a few stiff deflexed spines. Arizona.— 

 One of the most attractive of the cylindrical Opuntias 

 on account of its numerous bright scarlet fruits. 



,59. arbiiscula, Engelm. A short, numerously branched, 

 round-headed, arborescent plant, rarely reaching the 





1549. Opuntia ramosissima. Ko. Gl 



height of 5 ft., but always with an upright, well-defined 

 trunk, having rough, brown, unarmed bark: joints usu- 

 ally 2—4 in. long and % in. wide, easily broken from the 

 plant: areolae 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, %-!% in. long, loosely sheathed: fls. 

 bronze-colored, J-4-I in. wide: fr. unarmed, of same color 



