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



21. Opuntia stanlyi Engelm. in Emory, Mil. Reconn. 158. 1848. 



Corynopuntia stanlyi Knuth in Back, and Knuth, Kaktus- 

 ABC 114. 1935. 



Greenlee, Graham, Gila, and Pinal Counties, common, 2,000 to 

 5,000 feet, June. Southwestern New Mexico and Arizona. 



22. Opuntia kunzei Rose, Smithsn. Inst. Misc. Collect. 50: 505. 1908. 



Pinal and Pima Counties, 1,300 to 2,000 feet, June, type from Pima 

 County. Known only from Arizona. 



23. Opuntia wrightiana (Baxter) Peebles, Desert Plant Life 9: 43. 



1937. 



Grusonia wrightiana Baxter, California Cactus 58. 1935. 



Western Pima County and Yuma County, 500 to 2,000 feet, May 

 and June, type from Yuma County. Arizona, southeastern California, 

 and Sonora. 



Closely related to Opuntia kunzei, but the joints are larger, differ- 

 ently shaped, and even more heavily armed. The distinguishing 

 characters are not well marked in plants found in extreme western 

 Pima County. 



24. Opuntia ramosissima Engelm., Amer. Jour. Sci. ter. 2, 14: 339. 



1852. 



Cylindropuntia ramosissima Knuth in Back, and Knuth, Kak- 

 tus-ABC 122. 1935. 



Mohave, Maricopa, and Yuma Counties, 500 to 2,000 feet, May to 

 September. Southwestern Utah and Nevada to Sonora and California. 



25. Opuntia arbuscula Engelm., Amer. Acad. Arts and Sci. Proc. 3: 



309. 1856. 



Cylindropuntia arbuscula Knuth in Back, and Knuth, Kaktus- 

 ABC 123. 1935. 



Maricopa, Pinal, Pima, and Yuma Counties, 1,000 to 3,000 feet, 

 May and June, type from Pinal County. Arizona and Sonora. 



Pencil cholla (pi. 26). Typically an arborescent shrub with com- 

 pactly branched crown and well-developed trunk, but not infrequently 

 the plant is less than 1 m. high and openly branched. The Papago 

 Indians utilized the young joints of the pencil cholla and similar 

 species as a boiled vegetable, but probably only in times of want. 



The obscure tubercles and large fruits of Opuntia vivipara Rose, which is known 

 only from a few plants in the vicinity of Tucson, Pima County, indicate relation- 

 ship with O. arbuscula. On the other hand, O. vivipara resembles O. tetracantha 

 in having 1 to 4 spines at an areole, these only 2 to 4 cm. long, and purplish 

 flowers. 



26. Opuntia tetracantha Tourney, Gard. and Forest 9: 432. 1896. 



Cylindropuntia tetracantha Knuth in Back, and Knuth, Kaktus- 

 ABC 124. 1935. 



Cochise, Pinal, and Pima Counties, infrequent, May, type from 

 Pima County. Known only from Arizona. 



