718 CONTRIBUTIONS FROM THE NATIONAL HERBARIUM. 



91. P SILO STROPHE DC. 



Low, corymbosely branched, woolly perennial herbs with alternate, spatulate to 

 linear, often pinnatifid leaves and small heads of yellow flowers with persistent yellow 

 rays; involucre cylindric-campanulate, of 4 to 10 woolly bracts; achenes narrow, 

 terete, obscurely striate; pappus of 4 to 6 hyaline palese. 



KEY TO THE SPECIES. 



Stems covered with a dense matted tomentum; heads long-peduncu- 

 late; rays 15 mm. long or more 1. P. coo-peri. 



Stems not densely matted-tomentose, the pubescence loose; heads 

 short-pedunculate; rays 10 mm. long or less. 



Stems densely villous or floccose 2. P. tagetina. 



Stems scantily pubescent, often nearly glabrous, softly hirsute. 3. P. sparsiflora. 



1. Psilostrophe cooperi (A. Gray) Greene, Pittonia 2: 176. 1891. 

 Riddellia cooperi A. Gray, Proc. Amer. Acad. 7: 358. 1868. 

 Type locality: Gravelly banks at Fort Mohave, California. 

 Range: Southern California to southwestern New Mexico. 



New Mexico: Near Duncan (Davidson 1032). Dry plains and hills, in the Lower 

 Sonoran Zone. 



The handsomest species of the genus by its very large heads whose brilliant rays 

 contrast well with the white stems. 



2. Psilostrophe tagetinae (Nutt.) Britt. & Brown, Illustr. Fl. 3: 444. 1898. 

 Riddellia tagetinae Nutt. Trans. Amer. Phil. Soc. n. ser. 7: 371. 1841. 



Type locality: "The southern range of the Rocky Mountains, toward the sources 

 of the Platte." 



Range: Colorado to western Texas and southern Arizona. , 



New Mexico: West of Santa Fe; Cebolla Spring; Pajarito Park; Zuni; Reserve; 

 Sandia Mountains; Mangas Springs; Black Range; Gila Hot Springs; Magdalena; 

 San Luis Mountains; Strauss Station; Mesilla Valley; Organ Mountains; Tucumcari; 

 Tularosa; White Sands; Jarilla; Buchanan; Melrose; Guadalupe Mountains; west of 

 Roswell. Dry plains and low hills, in the Lower and Upper Sonoran zones. 



3. Psilostrophe sparsiflora (A. Gray) A. Nels. Proc. Biol. Soc. Washington 16: 



23. 1903. 

 Riddellia tagetina sparsiflora A. Gray, Syn. Fl. I 2 : 318. 1884. 

 Type locality: Southern Utah. 



Range: Southern Utah to northern Arizona and New Mexico. 

 New Mexico: Mesa La Vaca (Marsh). Dry hills, in the Upper Sonoran Zone. 



92. BAILEYA Harv. & Gray. 



Densely floccose-woolly biennial or perennial with alternate pinnatifid leaves and 

 long-pedunculate heads of yellow flowers with showy, bright yellow, persistent rays, 

 these reflexed in age; involucre hemispheric, of numerous linear bracts in 2 or 3 series, 

 very woolly; achenes oblong-linear or clavate, angled, striate; pappus none. 



1. Baileya multiradiata Harv. & Gray in Emory, Mil. Reconn. 144. pi. 6. 1848. 



Baileya pleniradiata Harv. & Gray, Mem. Amer. Acad. n. ser. 4: 105. 1849. 



Type locality: Along the Rio Grande, New Mexico. Type collected by Emory. 



Range: Western Texas to southern Utah and California, southward into Mexico. 



New Mexico: Albuquerque; Pajarito Park; Socorro; Mangas Springs; FloridaMoun- 

 tains; Dog Spring; Mesilla Valley; mesa west of Organ Mountains; Orogrande; Three 

 Rivers. Dry plains and low hills, in the Lower Sonoran Zone. 



A very handsome plant, common on the mesas in early spring. Sometimes the plants 

 continue flowering until late in the fall. 



