2362 



OPUNTIA 



OPUNTIA 



2601. Opuntia Engelmannii. ( X 3 o) 



18. Engelmannii, Salm-Dyck. Fig. 2601. An erect to 

 semi-prostrate, profusely branching, coarse plant^ 2-5 

 ft. high, forming large, impenetrable thickets, usually 

 with a short, more or less terete, woody trunk, with 

 grayish bark which becomes unarmed with age: joints 

 broadly obovate to orbicular, pale to bluish green, very 



variable in size, 

 in large specimens 

 12-14 in. long and 

 nearly as wide, 

 moderately thick: 

 areoles remote, 

 about 1 in. apart, 

 with gray wool 

 and large, rigid, 

 gray to yellow, 

 unequal bristles: 

 spines mostly 2-4, 

 sometimes 13 

 small additional 

 ones, very vari- 

 able, horny, vari- 

 ously colored, 

 mostly yellow, or 

 white with reddish 

 base, usually com- 

 pressed or angular 

 and curved or 

 twisted: fls. yel- 

 low, red within, fading to red, 2J^-3 in. diam.: fr. 

 broadly pyriform to globose, frequently 2 in. diam., 

 dark purple, with insipid purple flesh. U. S. and Mex. 

 This species, with its numerous varieties, is the most 

 widely distributed and abundant of the large, flat- 

 stemmed opuntias in the U. S. It varies greatly in dif- 

 ferent localities, and its many forms have not as yet 

 been adequately defined. 



19. phaeacantha, Engelm. A diffuse, semi-prostrate 

 plant, 1-2 ft. high, and freely rooting from lower mar- 

 gin of joints: joints broadly obovate, moderately thick, 

 4-6 in. long: areoles about 1 in. apart, with short wool 

 and reddish or brownish bristles; spines mostly toward 

 margin or on apex of joints, 2-5, straight and stiff, 

 reddish brown to almost black with lighter tips, 1-2 J^ 

 in. long: fls. 2J^ m - broad, yellow: fr. usually long- 

 pyriform, 1 in. or less diam. and twice as long, purple, 

 with greenish acid pulp. S. W. U. S. and Mex. Var. 

 major, Hort., is a good form. This species and a 

 number of the following become deep purplish green 

 during autumn and winter. In the spring they lose 

 their purplish color to a large extent and take it on 

 again in the fall. The spines are also much darker in 

 whiter than in summer. 



20. Caminchica, Engelm. & Bigel. A prostrate, 

 widely spreading plant 1-2 ^ ft. high, and freely root- 

 ing at the lower margin of the joints: joints broadly 

 obovate to orbicular, 4-6 in. long, moderately thick: 

 areoles about 1 in. apart, with light brown short wool 

 and yellowish brown bristles, mostly armed; spines 

 very variable, usually 1-3, sometimes 3-6, on marginal 

 areoles, reddish to blackish brown with lighter tips, 

 variable in length, sometimes 2J^ in. long: fls. 2J^-3 in. 

 wide, yellow, with reddish center: fr. oval to globose, 

 sometimes pyriform, deep red, sweet, edible, 1-1 ^ in. 

 diam. S. W. U. S. Var. gigantea, Hort., of the trade 

 proves to be 0. phaeacantha. 



21. macrocentra, Engelm. A semi-prostrate, spread- 

 ing plant, 2-3 ft. high: joints strikingly purple-green, 

 very thin, broadly obovate to nearly orbicular, 5-9 in. 

 diam., with a few remarkably long spines on the mar- 

 ginal areoles: areoles about 1 in. apart, grayish wool 

 and short grayish yellow bristles; spines rarely wanting, 

 usually 1-2, reddish brown to almost black, annulate, 

 3-5 in. long, slender and straight or variously twisted, 

 sometimes 1-3 much smaller, lighter colored, secondary 



spines: fls. 3 in. wide, yellow: fr. oval to globose, rarely 

 ovate, 1 in. diam., red; pulp sweet, edible. S. W. U. S., 

 Mex. This species is remarkable for its exceedingly 

 long, dark spines and purple joints. 



22. nigricans, Haw. A large, robust, upright plant, 

 2-5 ft. high: joints usually obovate, dark green, rarely 

 tinged with purple, about 10 in. long and 6 in. wide, 

 moderately thick: areoles with short, grayish wool and 

 yellowish brown bristles; spines 1-2, awl-shaped, 1-2 

 in. long, strong, dark brown, at first yellowish: fls. 

 lJ^-2 in. wide, yellow with red center. Mex. Fre- 

 quent in cult. 



23. filipendula, Engelm. A small, semi-prostrate 

 plant, freely branching from the base of the joints, rarely 

 10 in. high and with thick, tuberous, moniliform roots: 

 joints small and thin, bluish, glaucous, rarely 3 in. 

 greatest diam., orbicular to broadly obovate, sometimes 

 diamond-shaped, frequently flattened at the top and 

 broader than long: areoles orbicular and with an abun- 

 dance of whitish wool and many long, slender, yellowish 

 green bristles, which are very conspicuous, particularly 

 on the older joints; spines sometimes wanting, when 

 present usually 1-3, rarely more, white, very slender 

 and flexible, 1-2 in. long, mostly marginal: fls. yellow, 

 lJ^-2 in. diam.: fr. clayate to narrowly obovate, 1% 

 in. long and half as wide, greenish yellow, with few 

 seeds. Texas to Ariz., extending into Mex. 



24. humifusa, Raf. (0. Rafinesquii, Engelm. 0. 

 mesacdntha, Raf.). Fig. 2602 (adapted from Pacific R. 

 R. Report). A wide-spreading, prostrate plant, freely 

 rooting from the lower margin of the joints, roots some- 

 tunes tuberous: joints obovate to orbicular, usually 

 2-5 in. long and 2-4 in. wide, sometimes twice as large, 

 dark to light green: areoles with gray wool and bright 

 reddish brown bristles; spines sometimes wanting, when 

 present 1-3 and mostly marginal, stout, 1 in. long, 

 white with darker tips and bases, frequently 1-3 small 

 secondary spines also present: fls. 3 in. or less diam., 

 golden yellow, frequently with reddish center: fr. 

 slender-clavate or broader, 1^-2 in. long, yellowish red 



2602. Opuntia humifusa. 



