542 MISC. PUBLICATION 4 2 3, TJ. S. DEPT. OF AGRICULTURE 



17. Euphorbia exstipulata Engelm. in Torr., U. S. and Mex. Bound. 

 Bot. 189. 1859. 



Zygophyllidium exstipulatum Woot. and Standi., Contrib. U. S. 

 Natl. Herbarium 16: 146. 1913. 



Coconino, Mohave, Cochise, and Pima Counties, 4,200 to 5,900 

 feet. New Mexico, Arizona, and northern Mexico. 



*18. Euphorbia platysperma Engelm. ex S. Wats., Bot. Calif. 2: 482. 

 1880. 



Euphorbia eremica Jepson, Man. Fl. PL Calif. 600. 1925. 



An extremely rare species known only from the type, collected by 

 Edward Palmer in 1869 "near the mouth of the Colorado River, 

 Arizona," and from a single collection by Jepson in the Colorado 

 Desert, California. The plant may not occur in Arizona but should 

 be sought in the Yuma region. 



19. Euphorbia ocellata Dur. and Hilg., Acad. Nat. Sci. Phila. Jour. 



ser. 2, 3: 46. 1855. 



Virgin River, Mohave County, about 1,500 feet (Purpus 6187). 



The Arizona plant is var. arenicola (Parish) Jepson (E. arenicola 

 Parish), which ranges from Utah to southeastern California. 



20. Euphorbia parryi Engelm., Amer. Nat. 9: 350. 1875. 



Euphorbia flag elliformis Engelm. in T. S. Brandeg., U. S. Geol. 



Geog. Survey Terr. Bui. 2: 243. 1876. 

 Chamaesyce flagelliformis Rydb., Colo. Expt. Sta. Bui. 100: 



223. 1906. 

 Chamaesyce parryi Rydb., Torrey Bot. Club Bui. 40: 53. 1913. 



Apache County to northern Mohave County, south to Graham and 

 Cochise Counties, 1,600 to 5,500 feet, sandy soil. Colorado and 

 western Texas to California and Chihuahua. 



21. Euphorbia florida Engelm. in Torr., U. S. and Mex. Bound. Bot. 



189. 1859. 



Chamaesyce florida Millsp., Field Museum Nat. Hist. Bot. Ser. 

 2: 409. 1916. 



Yavapai, Graham, Gila, Pinal, Cochise, Santa Cruz, and Pima 

 Counties, 2,000 to 5,000 feet, type from west of the Chiricahua 

 Mountains, Cochise County (Wright in 1851). Arizona and north- 

 western Mexico. 



22. Euphorbia trachysperma Engelm. in Torr,, U. S. and Mex. 



Bound. Bot. 189. 1859. 



Chamaesyce trachysperma Millsp., Field Museum Nat. Hist. 

 Bot. Ser. 2: 412. 1916. 



Maricopa (Pinal County), San Pedro River valley (Cochise County), 

 Tucson (Pima County), near La Paz (Yuma County), very rare, 300 

 to 4,000 feet, type from along the San Pedro River {Wright 1832). 

 Southern Arizona and Sonora. 



