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138 



THE CACTACEAE. 



In 1885 C. G. Pringle again collected this species near Chihuahua City and it was dis- 



3:428). 



filipendula, and there Coulter leaves Pringle s specimen 

 E. Palmer collected an abundance of material in 1908 v 

 pottsii, which Coulter omits and Schumann lists under i 

 'hihuahua specimens are the same as the Texas plants, i 



Herb 



Dyck. 



them, then Opuntia filipendula must give place to the older name of Salm 



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Illustrations: 



n _ 



Mex. Bound, pi. 68; Forster, Handb 

 : f. 60"; : W. Watson. Cact. Cult, f . 



fil 



Figu 



El 



135. Opuntia setispina Engelmann in Salm-Dyck, Cact. Hort. Dyck. 1849. 239. 1850. 



-' 



Stem branching and spreading, sometimes 9 to 12 dm. broad, with some of the branches com- 

 posed of 3 or 4 joints, erect and 6 dm. high; joints deep bluish green, somewhat glaucous, often 

 purpUsh at the areoles, sometimes more or less tinged with purple throughout, obovate to orbicular, 

 5 to 15 cm. in diameter; leaves minute, subulate; spines i to 6 from an areole, white, 2 to 3 cm. 

 long ; glochids yellow, very conspicuous on old joints; flowers yellow; fruit purplish, about 4 cm. long. 



f: 



Fig. 173.— Opuntia pottsii. X0.4. 



Type locality: 

 mann, Proc. Amer 



1856). 



Fig. 174. — Opuntia setispina. X0.4. 



mountains west of Chihuahua, Mexico (fide E 



stnbutton: Western Chihuahiia, Mexico. 



is species has long been known only from the type specimens; but in 1908 Dr. Rose 

 western Chihuahua, where this species is quite common ; our description is based 

 upon the specimens he then collected. 

 Figure 1 74 represents a joint of the plant collected by Dr. Rose near Mifiaca, Chi- 



1911 



huahua, in 1908. 



136. Opuntia mackensenii Rose, Contr. U. S. Nat. Herb. 13: 310. 



Plants low, with thick, tuberous roots, spreading, usually resting on the edges of the joints, but 

 some of the branches^often erect; joints orbicular to obovate, 10 to 20 cm. long, rarely broader than 

 long, pale and glaucous when young, deep green when older; areoles small, the lower ones without 

 spmes, the upper ones with i to 4 spines; spines white or brown, or brown at base and white above, 

 somewhat flattened and tvyisted, slender, 5 cm. long or less; glochids brown; flowers of medium size, 

 7 to 8 cm. broad, yellow with a reddish brown center; stigma-lobes 7 to 9, white; fruit spineless, 4 to 

 6 cm. long, truncate or nearly so at apex, rose-purple; seeds suborbicular, 5 to 6 mm. broad, acute 

 on the margin. ^ . 



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