CACTUS FAMILY 149 



of several hundred stems. Joints orbicular to obovate, 1-5 cm. long, often greatly thickened, 

 subglobose, dark green, the terminal ones breaking off very easily ; areoles 2-3 mm. in diameter, 

 approximate, filled with white wool and a few light yellow glochids 1-4 mm. long ; spines (2) 

 5-7, straight, brown throughout or ashy yellow below, brown at tips, 1-3.5 cm. long, spreading, 

 or usually 1-3 subporrect; flowers yellow, 3-4 cm. long, 2.5-5 cm. broad w-hen expanded, fila- 

 ments reddish brown ; areoles on ovary bearing wool, glochids, and the upper ones a few acicular 

 spines 5-10 mm. long; fruit dry, 1.5-2 cm. long, sparsely spiny, with a slightly depressed 

 umbilicus ; seeds 5-6 mm. broad. 



Dry flats and hillsides. Transition and Upper Sonoran Zones; southern British Columbia east to Wisconsin 

 and Kansas, south to Siskiyou County, California, Arizona, and Texas. May-July. 



13. Opuntia hystricina Engelm. & Bigelow. Rock Tuna. Fig. 3313. 



Opuntia hystricina Engelm. & Bigelow in Engelm. Proc. Amer. Acad. 3: 299. 1856. 

 Opuntia rhodantha of authors, not Shum. 1896. 



A low, prostrate plant with numerous few- jointed stems forming mound-like clumps 2-3 dm. 

 high. Joints obovate to oblong or infrequently orbicular, 2.5-12 cm. long; areoles 10-15 mm. 

 apart, the lower ones of the joint containing brownish glochids and short wool only, the upper 

 ones spinose; spines 5-7, stout, subulate, brownish, 3-4 of them 1.5-3 cm. long, 2-3 accessory 

 ones shorter, less spreading; flowers (including the ovaries) 5-6 cm. long, 6-8 cm. wide when 

 expanded; petals pink or salmon color, obovate, 1.5-2.5 cm. long, apiculate; filaments yellow or 

 reddish; fruit dry, armed with brownish, spreading spines 1-2 cm. long; seeds flattened, 4-5 

 mm. in diameter. 



Rocky mountain sides and talus slopes, Canadian and Hudsonian Zones; vicinitv of Pinon Flats, San Tacinto 

 Mountains, Riverside County, and White Mountains, northeastern Inyo County, California, to -western Nebraska. 

 Aug. 



14. Opuntia polyacantha Haw. Plains Tuna. Fig. 3314. 



Cactus ferox T>!iin. Gen. PI. 1 : 296. 1818. Not Willd. 1813. 

 Opuntia polyacantha Haw. Suppl. Syn. PI. Succ. 82. 1819. 

 Opuntia missouriensis DC. Prod. 3: 472. 1828. 

 Opuntia Schwcriniana Schum. Monatss. Kakteenk. 9 : 148. 1899. 

 Tunas polyacantha Nwd. & Lunell, Amer. Midi. Nat. 4: 479. 1916. 



Low, spreading, freely branching plants forming small rounded clumps, 1-2 dm. high, 1 . 5-3 

 dm. in diameter. Joints orbicular to obovate or oblong, 3-10 cm. long, light green, glabrous ; 

 areoles circular to broadly elliptic, 2-3 mm. in diameter, 1 cm. or less apart, bearing dingy wool, 

 yellowish to reddish brown glochids, and ashy gray to dark brown spines ; spines 5-11, 7-20 mm. 

 long, on some plants 1-3 of these slender, somewhat flexuous, up to 6 cm. long ; marginal areoles 

 usually bearing 1-3 flexuous white, gray, or reddish brown spines 3-8 cm. long ; flowers 4-7 cm. 

 long; sepals tinged with red, apiculate; petals yellow, 2.5-4 cm. long, obovate, obtuse to emar- 

 ginate; fruit dry, oblong, 2-3 cm. long, bearing 1-7 light yellow or white spines 5-15 mm. long; 

 seeds 6 mm. long, the margins acute. 



Dry plains, hills and mountain valleys, in open or sparse pine woods. Arid Transition to Canadian Zones; 

 British Columbia to Alberta, North Dakota, eastern Oregon, Arizona, Utah, and Texas. June-July. 



15. Opuntia erinacea Engelm. & Bigelow. Old Man Prickly Pear. Fig. 3315. 



Opuntia erinacea Engelm. & Bigelow in Engelm. Proc. Amer. Acad. 3: 301. 1856. 



Low plants with prostrate stems and ascending or erect branches in dense clumps, 1-6 dm. 

 high, 1-3 m. in diameter. Joints suborbicular to ovate, 6-15 cm. long, light yellowish green; 

 areoles prominent, 7-12 mm. apart, 3-5 mm. in diameter, bearing ashy wool, numerous sordid- 

 yellow to reddish brown glochids 3-6 mm. long, and slender acicular spines; spines 3-11, white, 

 ashy or dark reddish brown, straight, 1.5-7 cm. long, spreading, 1-2 spines in each areole usually 

 1.5-3 times as long as the others; flowers, including the ovaries, 4-6 cm. long, nearly as broad, 

 greenish yellow tinged with pink to light red, the yellow flowers fading pink; outer petals 

 broadly obovate, apiculate, the inner 2-3 cm. long, obovate, the margins erosulate; fruit ovoid, 

 2.5-3 cm. long, closely covered with woolly areoles bearing stiff acicular spines 5-15 mm. long; 

 seeds 5-6 mm. broad. 



Gravelly washes and stony slopes, in desert mountains from 5,000 to 6,100 feet altitude. Upper Sonoran 

 Zone; Mono County, San Bernardino Mountains and eastern Mojave Desert, California, to southern Utah and 

 northern Arizona. April-June. 



Opuntia erinacea var. paucispina Dunkle, Bull. S. Calif. Acad. 34: 3. 1935. Joints bluish green; areoles 

 bearing 1-5 spines 0.5-4 cm. long. Vicinity of Ribbonwood, San Jacinto Mountains. 



16. Opuntia ursina Weber. Grizzly Bear Cactus. Fig. 3316. 



Opuntia ursina Weber in Bois, Diet. Hort. 2: 896. 1898. 



Opuntia erinacea var. ursina Parish in Jepson, Fl. Calif. 2: 542. 1936. 



A low, decumbent, branching plant 2-5 dm. high, forming dense mats 1-6 dm. wide. Joints 

 obovate to oblong, 5-8 cm. wide, 8-15 cm. long, light green; areoles orbicular to ovoid, 3 mni. 

 wide, 3-5 mm. long, 6-10 mm. apart, woolly when young, filled with yellowish to brownish 

 glochids 1-5 mm. long; spines 8-15, ashy gray to white, 2-20 cm. long bnstle-like reflexed. 

 flexuous, usually copious and concealing the surface; flowers 6-7 cm. long and wide; petals 



