OPUNTIA. 



60. Opuntia aoracantha Lemaire, Cact. Aliq. Nov. 34. 1838. 



Cereus ovatus Pfeiffer, Enum. Cact. 102. 1837. Not Opuntia mala PfeifTer, 1. c. 144. 

 Opuntia formidabilis Walton, Cact. Journ. i: 105. 1898. 



1837- 



Usually low, cespitose, forming clumps 2 to 5 dm. in diameter and sometimes i to 2 dm. high; 

 branches grayish, either erect or prostrate, made up of 5 to 10, perhaps even more, globular joints; 

 joints easily detached, freely rooting and starting new colonies, 5 to 8 cm. in diameter, strongly tuber- 

 culate especially when young, the lower part spineless, the upper areoles large, spine-bearing; spines 

 brown or blackish, i to 7, the longer ones 13 cm. long, straight, a little flattened, roughish to the 

 touch; flowers white; fruit short-oblong, 3 cm. long, red, weakly tuberculate, bearing numerous 

 areoles, usually naked but sometimes bearing a few short spines near the top, becoming dry; umbili- 

 cus of fruit broad and depressed; seeds white, flattened, 4 to 5 mm. broad, the margins thick and 

 corky. 



KlG. 105. Opuntia 



>.66. 



Type locality: Not cited, but doubtless from Mendoza. 



Distribution: Western provinces of Argentina, from Mendoza to Jujuy. 



Opuntia gilliesii Pfeiffer (Enum. Cact. 102. 1837, as synonym) and Tephrocactus 

 aoracanthus Lemaire (Cact. 89. 1868) are usually given as synonyms of this species, but 

 they were not described in the places usually cited, and as here given. Opuntia acra- 

 cantha Walpers (Repert. Bot. 2: 354. 1843) is a typographical error. 



0. aoracantha, although described nearly 80 years ago, is practically unknown in col- 

 lections and has been very poorly described. The fruit has heretofore been unknown. 

 Dr. Rose found it in 1915 in great abundance growing on dry, rocky hills west of Mendoza, 



