620 CONTRIBUTIONS FROM THE NATIONAL HERBARIUM. 



Flowers yellow or white. 



Achenes tapering upward; pap- 

 pus white; bracts in fruit 

 more or less thickened at 

 the base or on the mid- 

 rib 16. Crepis (p. 629). 



Achenes not tapering upward; 

 pappus usually sordid or 

 reddish, rarely white; 

 bracts not thickened 14. Hieracium (p. 627). 



1. PTILORIA Raf. 



Nearly or quite glabrous annuals or perennials with branched stems, a tuft of usu- 

 ally pinnatifid basal and small, often scalelike cauline leaves; heads small, 3 to 20- 

 flowered, paniculate or corymbose, with pink flowers; involucre cylindric, of several 

 narrow appressed bracts and a few short calyculate outer ones; achenes 5-angled, 

 often with intermediate ribs; pappus a single series of soft plumose bristles. 



KEY TO THE SPECIES. 



Annuals; pappus dilated at the base. 



Plants stout, simple at the base; stems very glaucous or nearly 



white 1. P. bigelovii. 



Plants slender, much branched from the base; stems green. . . 2. P. exigua. 

 Perennials; pappus not dilated at the base. 



Heads large, 10 to 20-flowered, 11 to 12 mm. high 3. P. thurberi. 



Heads smaller, 5 to 8-flowered, 9 mm. high or less. 



Plants low, seldom more than 20 cm. high, diffusely and 



densely branched 4. P. neomexicana. 



Plants taller, usually more than 30 cm., sparingly and not 

 diffusely branched. 



Pappus white, plumose to the base 5. P.ramosa. 



Pappus tawny, only scabrous at the base 6. P. pauciflora. 



1. Ptiloria bigelovii (A. Gray) Woot. & Standi. Contr. U. S. Nat. Herb. 16: 17G. 



1913. 

 Hemiptilium bigelovii A. Gray in Torr. U. S. & Mex, Bound. Bot. 105. 1859. 

 Type locality: Frontera, western Texas. 

 Range: Western Texas to Arizona. 



New Mexico: Farmington; mesa west of Organ Mountains. Dry hills and mesas, 

 in the Lower and Upper Sonoran zones. 



2. Ptiloria exigua (Nutt.) Greene, Pittonia 2: 132. 1890. 

 Stephanomeria exigua Nutt. Trans. Amer. Phil. Soc. n. ser. 7; 428. 1841. 

 Type locality: "On the Rocky Mountain plains, toward the Colorado." 

 Range: California and Nevada to Wyoming and New Mexico. 



New Mexico: Carrizo Mountains; Mesilla Valley. Dry hills and plains, in the 

 Lower and Upper Sonoran zones. 



3. Ptiloria thurberi (A. Gray) Greene, Pittonia 2: 133. 1890. 

 Stephanomeria thurberi A. Gray, Mem. Amer. Acad. n. ser. 5: 325. 1854. 

 Type locality: Sierra de las Animas, Sonora or New Mexico. 

 Range: Southwestern New Mexico to southern Arizona and southward. 

 New Mexico: Mangas Springs; Kingston. Lower and Upper Sonoran zones. 



