OPUNTIA. 



87 



at hand, they had the appearance of large, rounded, flattened cushions, some five or six feet in diam- 



unwary stranger who should be tempted to use one of these 



glistened with a silvery lustre. The 



ment. 



family 



needle-like spines, that penetrate the flesh, easily break, and are most difficult to extract. Unfor- 



A j1 jII** * 1*1T A A ^T^ 1*1 A * j1 * 



survive 



Dr. Rose found the plant very abundant in the Andes from 3,600 to 4,260 meters 

 altitude, while others have reported it as high as 4,570 meters altitude. It is very common, 

 forming everywhere great, conspicuous, usually white mounds. Dr. Rose also found it 

 quite common between Cuzco and Juliaca, in southwestern Peru. 



Mr. O. F. Cook, in the Journal of Heredity (8: 113. 1917), who has named this plant 

 the polar bear cactus, wrote of it as follows: 



Many exposed slopes on the bleak plateaus of the high Andes are dotted with clumps of pure 

 white cacti that look from a distance like small masses of snow. On closer view, the shaggy wliite 

 hair of these cacti make them appear Hke small sheep or poodle-dogs, or like reduced caricatures 

 of the denizens of the arctic regions. We are so accustomed to think of cacti primarily as desert 

 plants, peculiarly adapted to hot, dry deserts, that they seem distinctly out of place on the cold 

 plateaus of the high Andes of southern Peru. 



the plants are covered with long white hairs, plants without hairs 

 These naked plants, which are characteristic of the whole clump 



While most 



uncommon 



forms 



the same kind 



developed 



Weber seems to be only one of these naked forms 



(Salm 



' I 



^/ 



Opuntia involuta Otto (Forster, Handb. Cact. 505. 1846) was 

 given as a synonym of this species. It was used the year before 

 tenz. 13: 388. 1845) as a synonym of 0. vesiita. 



Illustrations: Engler and Drude, Veg. Erde 12: pi. 14; Monatsschr. Kakteenk. 11: 41, 

 44, these last two as Opuntia hempeliana; Journ. Heredity 8: f. 3 to 8. 



Plate XIII, figure 2, is from a photograph taken by Mr. O. F. Cook in the high moun- 

 tains of eastern Peru. Figure loi is from a photograph of a fragment of the plant col- 

 lected by Dr. Rose in 19 14, at Araranca, Peru. 



4- 



57. Opuntia lagopus Schumann, Gesamtb. Kakteen Nachtr. 151. 190^. 



Plants cespitose, growing in compact mounds; joints stout, cylindric, 10 cm Jong, 3 to 3.5 cm. in 

 diameter, densely covered with long white hairs; leaves minute, hidden under the wool 7 ^m. long; 

 spines sohtary. white, 2 cm. long, slender; glochids white, bnstle-like; flowers probably red. fruit 

 not known. 



Type locality: Mountains of Bolivia above Arequipa, Peru. . 



Distribution: On the plains of the high Andes of Peru and Bohvia (altitude 4,000 



meters). . , ^ •. ^ 1 



This species is related to 0. jloccosa, with which it often grows, but it takes on a very 

 different habit, growing in very dense, pecuHar rounded mounds much higher than those 



formed by O. fi 



W \y V ^^ * 



Engler and Drude, Veg. Erde 

 5 from a photograph by H. L. 



GLOMERATAE 



Plants low, composed of globose or oblon, joints t^^^^ t^^Z.^""' "°'"'"'^' '"" 



flat papery processes. We 



Key to SPEcms. 



Central spines papery; radial spines subulate 



Spines, when present, all developed into long papery processes 



58. 0, austral is 



59. 0. glomerata 



f^ 



