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



This and the following species are very similar, short-stemmed, 

 with large pale yellow or cream-colored flowers. 



2. Mentzelia tricuspis A. Gray, Amer. Nat. 9: 271. 1875. 

 Western Mohave County, 2,000 feet or lower, dry sandy soil, April. 



Southern Utah to western Arizona and southeastern California. 



3. Mentzelia aspera L., Sp. PL 516. 1753. 



Santa Cruz and Pima Counties, about 4,000 feet, thickets, August. 

 Widely distributed in tropical and subtropical America. 



4. Mentzelia asperula Woot. and Standi., Contrib. U. S. Natl. 



Herbarium 16: 148. 1913. 

 Cochise, Santa Cruz, and Pima Counties, 4,000 to 6,000 feet, 

 slopes and mesas, usually among shrubs, sometimes on limestone, 

 August and September. Western Texas to southern Arizona and 

 northern Mexico. 



5. Mentzelia affinis Greene, Pittonia 2: 103. 1890. 



Canyon Lake (Maricopa County), near Tucson (Pima County), 

 1,500 to 2,500 feet, March to June. Southern Arizona and California. 



Arizona specimens have smaller petals than most of those from 

 California and are scarcely distinguishable from M. albicaulis except 

 by the seed character. 



6. Mentzelia nitens Greene, Fl. Francisc. 234. 1891. 



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

 Counties, 3,000 feet or lower, February to May. Southern Utah, 

 Arizona, and southeastern California. 



Differs from M. albicaulis chiefly in its larger flowers and is con- 

 nected with it by var. jonesii (Urban and Gilg) J. Darlington, a 

 relatively small-flowered form with petals not more than 12 mm. 

 long and the upper leaves mostly entire or few-toothed. This variety 

 occurs in Arizona throughout the range of M. nitens and intergrades 

 completely with the typical form. Resembling var. jonesii, but 

 with slenderer stems and narrower leaves, is var. leptocaulis J. Darling- 

 ton, known only from the type collection on Williams River (Palmer 

 157). 



7. Mentzelia albicaulis Dougl. ex Hook., Fl. Bor. Amer. 1: 222. 



1834. 



Acrolasia albicaulis Rydb., Torrey Bot. Club Bui. 30: 277. 

 1903. 



Throughout the State, 7,000 feet or lower, very common in sandy 

 soil on plains and along washes, March to August. Wyoming to 

 Washington, south to New Mexico, Arizona, and California. 



Coextensive in range in Arizona with the typical form, and almost 

 equally abundant, is var. veatchiana (Kellogg) Urban and Gilg (M. 

 veatchiana Kellogg, M. gracilenta var. veatchiana Jepson) which has 

 petals 4 to 6 mm. long, whereas in typical M. albicaulis they are not 

 more than 4 mm. long. This form seems scarcely distinguishable 

 from M. albicaulis var. gracilis J. Darlington. Parched meal made 

 from the seeds of M. albicaulis was eaten by the Arizona Indians. 



