1610 CONTRIBUTIONS FROM THE NATIONAL HERBARIUM 



Coahuila and Durango; type from Chihuahua. Texas to New Mexico and 

 Nevada. 



Similar to D. pentachaeta, and distinguished chiefly by the diflFerence in pappus. 



15. Dyssodia aurantiaca (T. S. Brandeg.) Robinson, Proc. Amer. Acad. 49: 



507. 1913. 



H ymenatherum aurantiacum T. S. Brandeg. Zoe 5: 258. 1908. 



Thymophylla aurantiaca Rydb. N. Amer. Fl. 34: 175. 1915. 



Puebla; type from Cerro de Santa Lucia. 



Suffruticulose, ascending, 10 to 20 cm. high, glabrous; leaves chiefly alternate, 

 1.5 to 3 cm. long, pinnatisect with soft, linear-fihform, merely cuspidulate 

 divisions; heads l.S cm. wide; free portions of phyllaries ciliolate; pappus paleae 

 all split into 3 to 5 awns. 



16. Dyssodia setifolia (Lag.) Robinson, Proc. Amer. Acad. 49: 508. 1913. 

 Thymophylla setifolia Lag. Gen. & Sp. Nov. 25. 1816. 

 Hymenatherum setifolium A. Gray, Proc. Amer. Acad. 19: 42. 1883. 



H ymenatherum setifolium radiatum T. S. Brandeg. Univ. Calif. Publ. Bot. 4: 

 279. 1912. 



Coahuila and Nuevo Le6n, south to Queretaro; type from Mexico, without 

 definite locality. 



Suffruticulose, much branched, 7 to 20 cm. high, canescent-tomentose; leaves 

 pinnatisect, with 3 to 7 lobes, rather soft, about 1.5 cm. long; heads small, discoid 

 or rarely radiate; phyllaries with rather long triangular-subulate tips; pappus 

 of 5 to 10 free paleae, all short and blunt or the inner sometimes aristate. "Par- 

 ralena." 



17. Dyssodia greggii (A. Gray) Robinson, Proc. Amer. Acad. 49: 507. 1913. 

 Thymophylla greggii A. Gray, Mem. Amer. Acad. n. ser. 4: 92. 1849. 

 Thymophylla greggii radiata A. Gray, PI. Wright. 1: 119. 1852. 

 Hymenatherum greggii A. Gray, Proc. Amer. Acad. 19: 42. 1883. 

 Coahuila; type from Buena Vista. Texas and New Mexico. 



Similar to D. setifolia; leaves mostly trifid; heads usually radiate; pappus paleae 

 completely connate. 



100. POROPHYLLUM Adans. Fam. PI. 2: 122. 1763. 

 References: Robinson & Greenman, A provisional key to the species of 

 Porophyllum ranging north of the Isthmus of Panama, Proc. Amer. Acad. 32: 

 31-33. 1896; Rydb. N. Amer. Fl. 34: 181-193. 1916. 



Shrubs or herbs, often glaucous, glabrous; leaves opposite or alternate, entire, 

 sinuate, or rarely toothed, glandular-punctate on margin or apex and sometimes 

 on surface; heads discoid, j-ellow, whitish, or purple; involucre of few equal, nearly 

 1-seriate, firm phyllaries, usually glandular-punctate; achenes slender; pappus of 

 numerous bristles. 

 Leaves oval to elliptic, rarely lance-ovate, on distinct slender petioles. 



Heads more or less distinctly nodding, several or numerous and racemosely 

 cymose or cymose-panicled at tips of branches; flowers greenish. 



Leaves thick, veiny beneath 1. P. viridiflorum. 



Leaves thin, not veiny 2. P. nutans. 



Heads not nodding, cymose at tips of branches or solitary. 



Corollas purple above 3. P. nelsonii. 



Corollas greenish or ochroleucous. 



Heads solitary in the forks of the stem and at apex of branches, rarely 



paired 4. P. jorullense. 



Heads cymose. 



Leaves lanceolate or lance-ovate, acute or acuminate; phyllaries acu- 

 minate 5. P. palmeri . 



