612 MISC. PUBLICATION 42 3, U. S. DEPT. OF AGRICULTURE 



County. Southern Utah to Baja California, New Mexico, Arizona, 

 and Sonora. 



Pancake-pear, silverdollar cactus. 



12. Opuntia santa-rita (Griffiths and Hare) Rose, Smithsn. Inst. 



Misc. Collect. 52: 195. 1908. 



Opuntia chlorotica var. santa-rita Griffiths and Hare, N. Mex. 

 Agr. Expt. Sta. Bui. 60: 64. 1906. 



Cochise, Pima, and Santa Cruz Counties, 2,000 to 4,000 feet, 

 flowering in spring, type from the Celero Mountains. Arizona and 

 probably Sonora. 



Santa-rita cactus. The combination of bright-yellow flowers and 

 purple joints is very attractive, and the plant is often grown for 

 ornament. 0. santa-rita is closely related to 0. gosseliniana Weber. 

 Specimen plants on the campus of the University of Arizona that 

 seem to belong to the latter species were collected by A. A. Nichol 

 in western Pima County. This species of Sonora and Baja Cali- 

 fornia has the erect habit of 0. santa-rita, but the joints are well 

 armed on the sides. In Nichol' s specimens, the principal spines are 

 long and brown, and the secondary spines, when present, are strongly 

 deflexed or appressed. 



13. Opuntia macrocentra Engelm., Amer. Acad. Arts and Sci. Proc. 



3:292. 1856. 

 Greenlee County to Gila, Cochise, and Pima Counties, 2,000 to 

 5,000 feet, April and May. Western Texas, southern New Mexico, 

 Arizona, and northern Mexico. 



14. Opuntia laevis Coult., Contrib. U. S. Natl. Herbarium 3: 419. 



1896. 



Gila, Pinal, Cochise, and Pima Counties, 2,500 to 4,500 feet, in- 

 frequent, April and May, type from Pima County. Known only from 

 Arizona. 



Spineless cactus. The plant sometimes attains a height of 3 or 4 

 m. in protected and otherwise favorable situations. 



15. Opuntia gilvescens Griffiths, Mo. Bot. Gard. Ann. Rpt. 20: 87. 



1909. 



Pima and Santa Cruz Counties, 3,500 to 4,500 feet, infrequent in 

 arroyos and on detrital slopes, type from Pima County. Known only 

 from Arizona. 



This species is closely related to 0. laevis Coult. 



16. Opuntia flavescens Peebles, Cactus and Succulent Jour. 9: 67. 



1937. 



Pima County, 2,500 to 3,500 feet, April and May, t3^pe from near 

 Sells. Known only from Arizona. 



Closely related to O. phaeacantha Engelm., but the plant is larger 

 and of bushy habit. In southeastern Arizona plants with the gen- 

 eral character of O. flavescens but with more numerous and longer 

 spines are not infrequently encountered. They should, perhaps, be 

 referred to 0. flavescens rather than to 0. phaeacantha. 



