OPUNTIA 



OPUNTIA 



2365 



joints 4-7 in. long and ^-J^in. thick: areoles with 

 short, white wool and numerous straw-colored bristles; 

 spines usually 8-13, exterior J^in. or less long; interior 

 4-7, triangular, brownish, with lighter tips, %-lM in. 

 long, very loose-sheathed, fls. greenish yellow, 2-2 % 

 in. wide: fr. clavate, 1 in. or more long, often sterile, 

 spiny. Texas to Calif. 



46. acanthocarpa, 

 Engelm. & Bigel. Fig. 

 2606 (adapted from 

 Pacific R. R. Report). 

 An arborescent, erect 

 plant, 4-8 ft. high, with 

 dense reticulate-tubular 

 skeleton and ascending, 

 spreading branches: 

 joints usually 4-10 in. 

 long, sometimes 20, and 

 %-l in. diam.: areoles 

 with short, white wool 

 and scanty bright yel- 

 low bristles; spines very 

 variable in length and 

 numbers on different 

 plants, usually 8-25, 1 J^ 

 in. or less long, with 

 loose straw-colored or 

 brownish -sheaths: fls. 

 greenish yellow, with 

 reddish centers, con- 

 spicuous for stamens 

 with stout red filaments, 

 globose to pyriform, 1 in 



2607. Opuntia Bigelovii. 



%-1}4 in. wide: fr. sub- 

 diam. and usually armed 



with many long, stiff spines. Ariz, and Calif. A fac- 

 tory has been established at Tempe, Ariz., where the 

 wood of this species is made into light furniture, 

 picture-frames, and the like. 



47. echinocarpa, Engelm. & Bigel. A low, spreading 

 shrub, with reticulate woody skeleton, rarely more than 

 1% ft. high: joints lJ^-3 in. long, rarely 4-6 in., %in. 

 thick, somewhat clavate: areoles with short white 

 wool and a few coarse, straw-colored bristles, spines 

 very variable in length and number, exterior 8-16, \% 

 in. or less long; interior usually 4, forming a cross, 

 1-1 ^ in. long, with loose white or straw-colored 

 sheaths: fls. greenish yellow, IJ^-IM in- wide: fr. 

 depressed-globose or hemispherical and armed with 

 many long (1-1J^ in.) spines on the upper areoles. 

 Utah, Ariz., and Calif. The fr. of this species, like 

 most others with dry fr., ripens in the early summer, 

 while most species with fleshy fr. do not mature them 

 until fall or the following spring. 



48. Bernardina, Engelm. A slender, branched, 

 upright shrub, 3-5 ft. high, usually with several long, 

 straight sts. arising from the base: joints 4-24 in. long 

 and %in. thick, armed with numerous short spines: 

 areoles with grayish white wool and numerous yellow 

 bristles; spines yellow or brownish, 8-14, usually with 

 inconspicuous sheaths, %in. or less long: fls. greenish 

 yellow, 1-1 J^ in. wide: fr. obovate, 1 in. long, armed 

 with numerous rather short spines. S. Calif. 



49. serpentina, Engelm. A prostrate, rarely ascend- 

 ing, sparingly branched shrub, a few inches to 2 ft. 

 high: joints much elongated, 6-20 in. long and 3^-1 in. 

 thick: areoles with short white wool and whitish bris- 

 tles; spines comparatively short, usually 7-9, sometimes 

 15 or more, yellowish or rusty, J^in. or less long: fls. 

 greenish yellow, 1-1 ^j in. wide: fr. hemispherical, H~/4 

 in. diam., armed with numerous short spines and long 

 woolly hairs. S. Calif., Low. Calif. 



50. prolifera, Engelm. An arborescent, thick- 

 stemmed plant, 3-8 ft. high, with numerous horizontal, 

 spreading branches, the erect trunk sometimes 8 in. 

 diam : joints short-cylindrical, rounded at the ends, 

 very succulent, tumid and readily detached, bright 



green, 2-6 in. long and 1J4-2 in. thick: areoles with 

 white wool and on older joints with numerous straw- 

 colored bristles; spines variable, usually 6-10, with con- 

 spicuous, loose, yellowish or rusty sheaths and much- 

 barbed, usually about 1 in. long: fls. IM-l^j in. wide, 

 greenish red: fr. subglobose, %-l}4 in. diam., light 

 green, with few small spines and bristles, pendulous in 

 clusters, frequently sterile. Calif., Low. Calif. 



51. fulgida, Engelm. A numerously branched arbor- 

 escent plant, often 10-12 ft. high, with erect trunk 8-14 

 in. diam., having a thick, grayish, scaly, unarmed bark: 

 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: 

 areoles with white wool and bright straw-colored bris- 

 tles; spines on young growth 5-8, increasing yearly 

 until ultimately 30-50, finally deciduous, with loose, 

 glistening, white or straw-colored sheaths 1 J/ in. or less 

 long: fls. %-l in. wide, pink: fr. obovate to globose, light 

 green, pendulous, in large, proliferous clusters, some- 

 times 50 in a single cluster. S. W. II. S. and N. Mex. 

 The common "cholla" of the Ariz, plains, where it 

 often becomes a fair-sized tree and notable for its 

 formidable armor of barbed spines completely hiding 

 the surface of the plant. Var. mamillata, Coult. Differs 

 in having fewer, shorter spines. 



52. Bigelovii, Engelm. Fig. 2607 (adapted from 

 Pacific R. R. Report). 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 cylindrical opuntias: joints readily 

 detached and forming formidable burs, ovate, short- 

 elliptical to long and cylindrical, with rounded ends, 

 readily breaking from the plant and taking root, pale 

 green, fragile, tumid, terminal ones frequently 3-5 in. 

 long and half as thick: areoles close together, with white 

 wool and pale yellow bristles; spines 10-20, some very 

 small, increasing in number as sts. become older, straw- 

 colored, loose-sheathed, 1 in. or less long, completely 

 hiding the surface of the plant: fls. greenish red, 1 in. 

 broad: fr. very spiny, ovate, 1)^-2 in. long and one- 

 third as wide, few-seeded, mostly sterile. Ariz., Calif. 



53. imbricate, DC. A wide-spreading, irregularly 

 branching shrub, rarely more than 5 ft. high, the trunk 

 and larger branches with dark, rough, unarmed bark: 

 joints frequently 12-14 in. long and 1-1 M in- thick, 

 with very prominent long, cristate tubercles: areoles 



with yellowish wool 

 and straw - colored 

 bristles; spines 2-5, 

 of variable length, 

 1 hi. or less long, 

 loosely sheathed, 

 white to straw- 

 colored: fls. 2-2 % 

 in. wide, light pur- 

 ple: fr. unarmed, 

 depressed - globose, 

 with large tubercles, 

 yellow, 1-1 Yi in. 

 diam., adhering to 

 the plant and dry- 

 ing on the sts. 

 during the winter. 

 Texas and N. Mex. 

 Usually confused 

 with O. arborescens, 

 from which it dif- 

 fers in its smaller 

 growth, different 

 habit, much longer 

 joints, larger, more 

 2608. Opuntia arborescens. prominent tuber- 



