302 DESCRIPTIONS OF NEW SPECIES 



cies, though with yellow flowers, ought to find place in this genus, rather than 

 the polymorphous one of Aplopappus, to which it is not allied. 



Subgenus. — Pappochroma. Annual or biennial. Capitulum hemispherical. 

 Receptacle nearly naked. Involucrum loosely imbricated, of about three 

 series of nearly equal, narrow sepals, spreading towards the points. Pappus 

 of the disk and ray equal. Achenium obovate, villous, with fifteen striae. 

 Rays purple, longer than the wide disk. Leaves pinnatifid and bipinnatifid. 



Dieteria * coronopifolia; pubescent and viscid, branching from the base, 

 branches fastigiate one-flowered; lower leaves bipinnatifid, the upper pinna- 

 tifid. Chrysopsis coronopifolia, Nutt., in Journ. Acad. Nat. Sci. Philad., Vol. 



VII., p. 34. 



Hab. From the Platte to the sources of the Missouri, and throughout the Rocky Mountain tract, 

 in arid, denudated places, by streams. Flowering from July to August. A very showy and orna- 

 mental plant, with hemispherical heads nearly as large as the garden marigold. Sepals linear- 

 lanceolate, acuminate, nearly equal, scarious and cartilaginous towards the base. Rays eighteen 

 to twenty, wide and long, of a fine red purple. Achenia turgid, rather large; stem about a foot 

 high, somewhat spreading. 



SERICOCARPUS. (Nees.) 



Obs. — Pappus unequal, scabrous, the longer rays clavellate. Liguli short 

 and few. 



Sericocarpus rigidus. /3. ^Icevicaulis, leaves cuneate-oblong, or spathulate; 

 rays shorter than the pappus. 



Hab. Round Fort Vancouver, common. Leaves usually obtuse. 



Sericocarpus * Oregonensis; leaves lanceolate-oblong, entire, and, as well as 

 the involucrum, glandular beneath, above scabrous; stem smooth, corymb com- 

 pound; inner scales of the involucrum acute; rays longer than the pappus. 



Hab. With the above, which it much resembles, but appears taller and stouter. Stem attenu- 

 ated. Pappus distinctly scabrous, the inner row obviously clavellate, less distinctly so in S. rigi- 

 dus. The discal florets are also exserted beyond the pappus. Stigmas filiform, acute, nearly 

 smooth, glandular. In both these species the pappus is unusually long and silky white. 



Sericocarpus Collinsii. With the whole aspect and pubescence of S. torti- 

 folius, but the leaves cuneate and serrate at the summit. Scales of the invo- 

 lucrum fewer. Aster Collinsii, Nutt. East Florida. (Mr. Ware.) 



