FLOWERING PLAXTS AND FERNS OF ARIZONA 463 



3. Corolla rose-colored or purplish; blade of the banner shorter than the 

 claw (4). 



4. Stems and leaves sparsely villous or glabrate: stems very leafy almost 

 to the inflorescence, with additional leaves often fascicled in the 

 axils: leaflets commonly 5, narrowly linear, about 1 mm. wide, 

 mucronate, strongly involute; peduncles commonly not more than 

 2 cm. long: calyx tube densely silky-villous 4. " P. purpureum. 



4. Stems and leaves glabrous: stems not very leafy, naked for a consider- 

 able distance below the inflorescence: leaflets 5 to 9, elliptic to 

 obovate, 2 to 4 mm. wide, not strongly involute: peduncles up to 

 15 cm. long; calyx tube loosely pilose or villous, _ 5. P. searlsiae. 



1. Petalostemum candidum Michx., Fl. Bor. Amer. 2: 49. 1803. 



Apache County to Coconino County, south to Cochise, Santa Cruz, 

 and Pima Counties. 3.000 to 7,000 feet, mesas and openings in pine 

 forests, rather common, May to September. Indiana to Saskatche- 

 wan and Montana, south to Mississippi, Texas, Arizona, and northern 

 Mexico. 



White prairieclover. The species is represented in Arizona by a 

 western form (Petalostemon oligophyllus (Torr.) Rydb., P. sonorae 

 Rydb.). in which the leaflets are usually smaller and narrower than in 

 P. candidum as it occurs farther east. The plant is reported to be 

 used by the Hopi Indians as an emetic. 



2. Petalostemum exile A. Gray, PL Wright. 2: 41. 1853. 

 Cochise, Santa Cruz, and Pima Counties, 5,000 to 7.000 feet, mostly 



among pines, September. Southern Xew Mexico and Arizona, and 

 northern Mexico. 



3. Petalostemum flavescens S. Wats., Amer. Xat. 7: 299. 1873. 

 Navajo and Coconino Counties. 5,000 to 8,000 feet, apparently 



rare, June. Southern Utah and northernmost Arizona. 



The corolla was described as yellow by Watson but is white in fresh 

 specimens. The crushed foliage is lemon-scented. 



4. Petalostemum purpureum (Vent.) Rydb., X. Y. Bot. Gard. Mem. 



1:238. 1900. 



Dalea purpurea Vent., PI. Jard. Cels. pi. 40. 1800. 



Near Prescott. Yavapai County (Peebles et al. 4253) at roadside, 

 July. Indiana to Saskatchewan, south to Texas and central Arizona, 

 where perhaps irtroduced from farther east. 



5. Petalostemum searlsiae A. Gray, Amer. Acad. Arts, and Sci. 



Proc. 8: 380. 1873. 



Petalostemon rothrockii Rydb., Xorth Amer. Fl. 24: 134. 1920. 



Coconino, eastern Mohave, and northern Yavapai Counties, 3.000 

 to 7.000 feet, June. Southern Utah and Nevada, northern Arizona. 



The type of P. rothrockii was collected in Arizona (Roth rock in 1874, 

 without definite locality). It differs from most specimens of P. 

 searlsiae in the broader, more abruptly acuminate bracts, but inter- 

 gradations occur. 



Petalostemon pilosulus Rydb. was described from a specimen collected by 

 Xealley (Xo. 237 >, probably in the Rincon Mountains, Pima County. The type 

 appears to be a form of Dalea alhi flora. 



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