196 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 52 



throughout; areoles 1.5 cm. apart, bearing chestnut-brown bristles; 

 spines usually wanting, when present single or sometimes two, 2 

 to 4 cm. long, needle-like, chestnut-brown; ovary purplish, shortly 

 oblong; flowers very handsome, of deep yellow color, 6 to 7 cm. 

 broad. 



Collected by J. N. Rose in waste ground in Tucson, Arizona, 

 April 26, 1908 (no. 11922). This species is common on the foot- 

 hills about Tucson and extends south nearly or quite to the Mexican 

 border. 



This plant was described in 1906 by Griffiths and Hare as a sub- 

 species of Opuntia chlorotica, but it seems to me to be a distinct 

 species. 



Explanation of Plate xv. — Made from a photograph taken by 

 Dr. D. T. MacDougal at Surritas, Arizona, February, 1907, and 

 here used through the courtesy of the Carnegie Institution of Wash- 

 ington. 



