CACTACEAE (CACTUS FAMILY) 



'2. Opuntia camanchica Engelm. & Bigel. Proc. Amer. Acad. 3: 293. 1856. 



I'roMrate ;md extensively spreading, with ascending, obovate-orbicular joints 



5 cm. long by 13.5-17.5 cm. broad: pulvini about 3 cm. apart, with 



few greenish or yellowish-brown bristles, mostly armed: spines 1-3 (or mar- 



angular, with broad, thick, acute or obtuse margins and deeply notched at the 

 hilum, 4-0 m. broad. Colorado to Texas. 



:;. Opuntia Schweriniana K. Sch. Monatsschr. Kakt. 9: 148. 1899. Joints 

 oblong, tuberculate: spines 5-7, white: flower yellow. Reported from our 

 range. 



1. Opuntia tortispina Engeirn. 1. c. 293. Prostrate, with ascending, or- 

 bicular-obovate joints 15-20 cm. long: pulvini 2.5-3.5 cm. apart, with yel- 

 lowish bristles: spines 3-5, white, angular and channeled, often spirally 

 twisted, 3.5-6 cm. long, with 2-4 more slender ones (1-2.5 cm. long) added 

 In -low: flowers sulphur-yellow, 6-7.5 cm. broad: fruit ovate, with broad um- 

 bilicus, 4.5-5 cm. long: seeds orbicular, regular, and but slightly notched at 

 hilum, 4-6 mm. broad. Nebraska and Colorado to Oklahoma. 



5. Opuntia polyacantha Haw. Suppl. PI. Succ. 82. 1819. Prostrate, form- 

 ing large spreading masses: joints light green, orbicular, tuberculate, 5-10 cm. 

 (rarely 10-15 cm.) long: leaves minute, 3-4 mm. long: pulvini 8-12 mm. apart, 

 with reddish-brown bristles (fewer but longer and darker than in other forms), 

 all armed: spines 8-15; the 5-10 (generally 6-8) exterior ones radiant, seti- 

 form, whitish or reddish- variegated ; the 3-5 interior ones stout, reddish- 

 brown (paler-tipped), 3-5 cm. long, 2-4 of them deflexed, the other one 

 spreading or suberect and very stout: flowers yellow (orange within) or some- 

 times purple: stigmas 5-8: fruit ovate, dry, and spiny, with shallow, flat um- 

 bilicus, 2.5 cm. long: seeds irregular, large (5-6 mm. broad). Very variable; 

 some of the forms have been described. See Coulter's treatment in Contrib. 

 U. S. Nat. Herb. 3: 435. Plains on the eastern base of the Rocky Mountains. 



6. Opuntia xanthostemma K. Sch. Gesamtb. Kakteen 735. 1899. Very 

 branching, erect, low, obscurely green and sometimes purplish: joints ob- 

 ovate, tuberculate, subareolate: spines 2-4, with some accessory ones: flower 

 red, stamens yellow: ovary unarmed. Colorado. 



7. Opuntia rhodantha K. Sch. Gesamtb. Kakteen 735. 1899. Branching, 

 erect, low, green: joints obovate or oblong, subtuberculate : spines 2-4, some- 

 times with accessory ones: flowers and stamens red: ovary very spiny. 

 Colorado. 



s. Opuntia fragilis (Nutt.) Haw. 1. c. Subdecumbent, with small, ovate, 

 subcompressed or sub globose (even terete), scarcely tuberculate, shining green 

 joints, variable in size and shape (fruit-bearing ones compressed, 3.5-5 cm. 

 long by 2.5-3 cm. broad, the others smaller and more tumid): pulvini large, 

 >> 1'J mm. apart, with white wool, and very few, short, whitish bristles (on old 

 joints a little more abundant, coarser, and straw-colored): spines 1-4 (mostly 

 1 and cruciate), the uppermost one stout, angular, suberect or porrect, 

 yellowish-brown, 12-20 mm. long, the others weaker (6-16 mm.), paler, 

 .-pivadin^ or radiant, and 2-6 additional slender, white radiant ones below, 

 1 x nun. long: flowers pale yellow, about 5 cm. broad: fruit ovate, almost 

 naked, with funnel form umbilicus, about 2.5 cm. long: seeds few, large (6 mm.), 

 with broad and thick, obtuse, corky margin. From British Columbia to Utah 

 and 1 



'.. Opuntia rutila Nutt. T. & G. Fl. 1: 555. 1840. Ascending and diffuse: 



wollen, ovate or teretish, 5-10 cm. long by 2.5-7.5 cm. broad (some- 



iMimaii-d and almost cylindrical): pulvini very crowded (4-6 mm. 



with \\hitc wool, and at length straw-colored bristles, all armed: 



3 "). slender, reddish-gray, 1-4 cm. long (1-3 upper shorter and erect, 



central one longer, spreading or declined, the rest deflexed, sometimes larger 



1 ittened and often twisted), 2-1 smaller ones added below: flowers 



I or paler: fruit ovate, dry, and spinulose, with a deep funnelform urn- 



