524 SMITHSONIAN MISCELLANEOUS COLLECTIONS [VOL. 50 



OPUNTIA PLUMBEA Rose, sp. nov. 



Plant low, creeping, 10 cm. high, 20 to 30 cm. broad, few-jointed; 

 joints small, nearly orbicular, 3 to 5 cm. in diameter, of a dull lead 

 color, the surface somewhat wrinkled in dead specimens ; areoles 

 rather large for the size of the joints ; spines pale brownish, slender, 

 usually porrect, often 3 cm. long, mostly 2 in number, rarely as 

 many as 4, sometimes 1 or even wanting; flowers very small, red; 

 ovary naked; fruit 1.5 to 2 cm. long with a few small areoles and 

 these simply woolly ; seeds small, rather turgid, smooth, and with a 

 shallow obtuse margin. 



Type U. S. National Herbarium, no. 399,804, collected by Mr. 

 F. V. Coville in the San Carlos Indian Reservation, Arizona, altitude 

 1,500 meters, June, 1904, and for a time growing in Washington. 



The fruit and seeds suggest 0. stenochila Engelm. 



OPUNTIA HUMIFUSA Raf. 



Cactus humifusus Raf. Ann. Nat. 15. 1820. 



Opuntia humifusa Raf. Med. Bot. 2:247. 1830. 



Opuntia mcsacantha Raf.; Ser. Bull. Bot. Geneva 216. 1830. 



Opuntia rafincsquii Engelm. Proc. Am. Acad. 3:295. 1856. 



Type locality : United States. 



Distribution : Central United States. 



Illustrations: Pac. R. Rep. 4: pi. 10. figs. 5-5; pi. 11; Fl. des 

 Serres pi. 2328; Bot. Mag. pi. 7041; 111. Fl. 2528; W. Watson, 

 Cactus Cult. fig. 84; Am. Entom. & Bot. 2 : fig. 160; Forst. Handb. 

 Cact. ed. 2. fig. 126, as 0. rafinesquii arkansana. 



The following forms, referred to O. mesacaiitha by Dr. Coulter, 

 we have not studied sufficiently to enable us to form opinions as to 

 their relationships : 



OPUNTIA MESACANTHA PARVA Coult. 



Opuntia mcsacantha parva Coult. Contr. Nat. Herb. 3:429. 1896. 



OPUNTIA MESACANTHA MICROSPERMA (Engelm.) Coult. 



Opuntia rafincsquii microsperma Engelm. Proc. Am. Acad. 3: 295. 1856. 

 Opuntia mcsacantha microsperma Coult. Contr. Nat. Herb. 3:429. 1896. 



OPUNTIA MESACANTHA OPLOCARPA Coult. 



Opuntia mesacaiitha oplocarpa Coult. Contr. Nat. Herb. 3:431. 1896. 



OPUNTIA GRANDIFLORA Engelm. 

 Opuntia grandiflora Engelm. Proc. Am. Acad. 3:295. 1856. 

 Opuntia rafincsquii grandiflora Engelm. Pac. R. Rep. 4: 55. 1856. 



