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



Key to the species 



1. Disk purple; pales of the receptacle comparatively firm; plant usually much- 

 branched above, with several to many small heads. 1. H. microcephala. 

 1. Disk yellow; pales of the receptacle soft and mainly scarious; plants usually 

 simple or little branched, the heads solitary or few (2). 

 2. Heads small, the disk not more than 1.5 cm. wide, the rays 2 cm. long or less; 

 leaves thick and firm, the basal and lower ones not more than 2.3 cm. 



wide 2. H. parryi. 



2. Heads large, the disk usually 2 to 3 cm. wide, the rays usually 3 cm. long or 

 more; leaves thin, the basal and lower ones 2.5 to 7.5 cm. wide. 



3. H. QUINQUENERVIS. 



1. Helianthella microcephala A. Gray, Amer. Acad. Arts and Sci. 



Proc. 19: 10. 1883. 



Encelia microcephala A. Gray, ibid. 8: 657. 1873. 



Carrizo Mountains, Apache County (Standley 7350). South- 

 western Colorado, southern Utah, northwestern New Mexico, and 

 northeastern Arizona, July and August. 



2. Helianthella parryi A. Gray, Acad. Nat. Sci. Phila. Proc. 1863: 65. 



1863. 

 White Mountains, Apache County (Griffiths 5266, Eggleston 17051), 

 8,500 feet, mountainsides, often under aspens, July to September. 

 Wyoming to New Mexico and eastern Arizona. 



3. Helianthella quinquenervis (Hook.) A. Gray, Amer. Acad. Arts and 



Sci. Proc. 19: 10. 1883. 



Helianthus quinquenervis Hook., London Jour. Bot. 6: 247. 



1847. 

 Helianthella quinquenervis var. arizonica A. Gray, Syn. Fl. 



1 2 : 284. 1884. 



White Mountains (Apache and Greenlee Counties), Kaibab Plateau 

 and Flagstaff (Coconino County), Pinal eno Mountains (Graham 

 County), Johnston Ranch (Cochise County), Santa Catalina Moun- 

 tains (Pima County), 5,000 to 10,000 feet, mountain meadows and 

 woods, July to September. South Dakota to Idaho (?), south to New 

 Mexico, Arizona, and Chihuahua. 



69. ZEXMENTA 85 



Perennial herb, the roots tuberous-thickened ; leaves opposite, ovate, 

 toothed, subsessile; heads medium-sized, yellow, radiate, solitary, 

 long-peduncled; rays pistillate; achenes obovate, compressed, 2- 

 winged; pappus of 2 slender awns and several small intermediate 

 squamellae, or the latter wanting. 



1. Zexmenia podocephala A. Gray, Syn. Fl. 1 2 : 286. 1884. 



Verbesina podocephala A. Gray, PI. Wright. 2: 92. 1853. 



Mountains of Cochise and Santa Cruz Counties, and Santa Rita 

 Mountains (Pima County), 4,000 to 5,000 feet, August and Sep- 

 tember. Southeastern Arizona and northern Mexico. 



85 Reference: Jones, W. W. a revision of the genus zexmenia. Amer. Acad. Arts and Sci. Proc. 41 

 (Gray Herbarium Contrib. 30): 143-167. 1905. 



