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



28. Euphorbia serpens H. B. K., Nov. Gen. et Sp. 2: 52. 1817. 



Chamaesyce serpens Small, Fl. Southeast. U. S. 709, 1333. 

 1903. 



Santa Cruz River at La Noria, Santa Cruz County, about 4,900 feet 

 (Mearns 1192). Ontario and Montana, south to South America. 



29. Euphorbia fendleri Torr. and Gray, U. S. Rpt. Expl. Miss. Pacif. 



2 2 : 175. 1855. 



Chamaesyce fendleri Small, Fl. Southeast. U. S. 710, 1333. 

 1903. 



Apache County to Mohave and Yavapai Counties, also at Dragoon 

 (Cochise County), 4,000 to 7,000 feet. Nebraska to Texas, west to 

 California. 



The var. chaetocalyx Boiss. (Chamaesyce chaetocalyx Woot. and 

 Standi.) occurs in most of the range of the species in Arizona, inter- 

 grading with the typical form in Navajo and Coconino Counties. 



30. Euphorbia polycarpa Benth., Bot. Voy. Sulph. 50. 1844. 



Chamaesyce polycarpa (Benth.) Millsp. in Parish, Cat. PL 

 Sal ton Sink 6. 1913. 



Mohave, southern Yavapai, Maricopa, Pima, and Yuma Counties, 

 600 to 2,800 feet, sandy or gravelly plains and mesas. Nevada to 

 Sonora, California, and Baja California. 



A pubescent variant, var. hirtella Boiss. (Chamaesyce tonsita 

 Millsp.) occurs in Mohave and Yuma Counties, intergrading with the 

 species, which is glabrous. 



31. Euphorbia melanadenia Torr., U. S. Rpt. Expl. Miss. Pacif. 4: 



135. 1857. 



Euphorbia polycarpa var. vestita S. Wats., Bot. Calif. 2: 73. 



1880. 

 Chamaesyce melanadenia Millsp., Field Museum Nat. Hist. 



Bot. Ser. 2: 410. 1916. 



In the entire southwestern half of the State, eastward to Gila 

 County, 500 to 4,900 feet, common on dry sunny foothills, often 

 among shrubs. Arizona, southern California, Sonora, and Baja 

 California. 



The plants are generally erect or ascending, but on open flats, 

 particularly in disturbed soil, they may be nearly prostrate. 



32. Euphorbia pediculifera Engelm. in Torr., U. S. and Mex. Bound. 



Bot. 186. 1859. 



Chamaesyce pediculifera Rose and Standi., Contrib. U. S. 



Natl. Herbarium 16: 12. 1912. 

 Euphorbia vermiformis M. E. Jones, Contrib. West. Bot. 16: 



23. 1930. 



Southern Yavapai, Maricopa, Pinal, Cochise, Santa Cruz, Pima, 

 and Yuma Counties, 500 to 4,000 feet. Arizona, southeastern Cali- 

 fornia, and northwestern Mexico. 



Specimens from the deserts at low altitude often simulate Euphorbia 

 melanadenia in pubescence and leaf size, but the ovoid-oblong seeds, 

 encircled by 4 or 5 ridges, of E. pediculifera are readily distinguishable 



