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



3. Chorizanthe rigida (Torr.) Torr. and Gray, Amer. Acad. Arts and 



Sci. Proc. 8: 198. 1870. 



Acanthogonum rigidum Torr., U. S. Rpt. Expl. Miss. Pacif 4 5 - 

 133. 1857. 



Pinal and Pima Counties to Mohave and Yuma Counties, 2,500 feet 

 or lower, March to April. Arizona, California, and Baja California. 



The blackened plants are persistent on the desert long after they 

 have died. 



4. Chorizanthe watsoni Torr. and Gray, Amer. Acad. Arts and Sci 



Proc. 8: 199. 1870. 

 Apparently only once collected in Arizona, at Chloride, Mohave 

 County (Jones in 1903). Washington to Arizona and California. 



5. Chorizanthe corrugata (Torr.) Torr. and Gray, Amer. Acad. Arts 



and Sci. Proc. 8: 198. 1870. 



Acanthogonum corrugatum Torr., U. S. Rpt. Expl. Miss. Pacif. 

 5 2 : 364. 1857. 



Western Maricopa and Pima Counties to Mohave and Yuma Coun- 

 ties, 1,000 feet or lower. Arizona, California, and Baja California. 



3. OXYTHECA 



Plant annual, small, slender-stemmed, dichotomously branched; 

 leaves with oblanceolate blades, the basal ones in a rosette, the stem 

 leaves opposite. 



1. Oxytheca perfoliata Torr. and Gray, Amer. Acad. Arts and Sci. 

 Proc. 8: 191. 1870. 

 Mohave Countv, at Fort Mohave (Lemmon in 1884) and north of 

 Chloride (Kearney and Peebles 11201), 500 to 2,000 feet, April. Ari- 

 zona, Nevada, and California. 



4. ERIOGONUM35 



Plants annual or perennial, herbaceous or shrubby; leaves alternate 

 or whorled, simple, entire, the larger ones often in a basal rosette and 

 the stem leaves often bractlike; flowers several or many in a campanu- 

 late, turbinate, or cylindric, toothed or lobed involucre, the involucres 

 arranged in cymose, racemose, or glomerate inflorescences, or some- 

 times solitary in the forks of the branches; perianth corollalike; sta- 

 mens 9; fruit an achene, usually triangular. 



This large genus is extraordinarily well represented in Arizona, in 

 number both of species and of individuals. Often the roads are 

 bordered for miles by plants of one species, notably skeletonweed (E. 

 dejiexum) in the low semidesert areas and E. wrightii in the foothills 

 and mountains. The shrubby species, known collectively as buck- 

 wheatbrush, furnish browse for livestock, and flat-top buckwheat- 

 brush or California-buckwheat (E. jasciculatum) is a valued honey 

 plant. 



35 Keference: Stokes, Susan G. the genus eriogonum, a preliminary study based on geographic 

 distribution. San Francisco. 1936. 



