AND GENERA OF PLANTS. 437 



nial. Stems scapoid, dichotomous, corymbose. Leaves runcinately pinna- 

 tifid; stem leaves linear, entire. — In habit allied to Prenanthes. 



Crepis * acuminata; x, stem smooth, above angular and paniculate; branches 

 corymbose, naked, many-flowered; leaves runcinately pinnatifid, acuminate, 

 pubescent; segments sublanceolate, sparingly laciniate, below attenuated into 

 a petiole; upper stem leaves linear, entire; involucrum smooth; involucel ap- 

 pressed, pubescent. 



Hab. Plains of the Platte. About a foot high. Root long, black, and fusiform. Radical leaves 

 about six inches long, with a lanceolate outline, one and a half to two inches wide in the middle, 

 more or less pubescent on botli surfaces. Flowers numerous and showy, bright yellow, with 

 exserted five-toothed liguli. Style and stigma exserted and hirsute. Receptacle scrobiculate. 

 Pappus copious, white and soft, a little barbellated. Central achenia longest, all ten striate, the 

 rostrum short and thick. C. elegans approaches this species in the involucrum, which is quite 

 similar; but the achenium is furnished with a long slender rostrum, which places it, artificially 

 enough, in the genus Barkhausia. It has also all the habit, as well as great affinity with Barkhausia 

 tenuifolia of Siberia. 



* PSILOCHENIA. 



Crepis, but with the achenium cylindric, curved, narrower above, and without 

 any visible striae, the testa indurated, and, when mature, black; an abortive 

 outer series of florets, with the achenium empty. Pappus copious, slenderly 

 pilose, scabrous, and yellowish white, about the length of the achenium. 

 Receptacle naked, alveolate, the alveoles minutely fringed. — A low perennial 

 herb; stem dichotomous and corymbose. Leaves lanceolate, runcinately 

 pinnatifid, and, as well as the somewhat hirsute involucrum, cinereously and 

 closely lanuginous; flowers yellow, rather large. 



Psilochenia * occidentalis. Crepis occidentalism Nutt. in Journ. Acad. Nat. 

 Sci. Philad., Vol. VIL, p. 29. 



Hab. On the plains of the Platte, towards the Rocky Mountains. The whole plant more or less 

 canescently pubescent. Stem about six or seven inches high, forked and corymbose at the summit. 

 Leaves about an inch wide, four or five inches long, deeply and runcinately pinnatifid, the segments 

 linear-lanceolate and denticulate, uppermost leaves linear. Involucrum campanulate ; sepals about 

 twelve to fifteen in a single series, linear and somewhat acute ; involucel or bractes four or five, 

 small and subulate: there are blackish hairs mixed with the hoary pubescence of the sepals. Florets 

 about twelve, yellow, exserted. 



VII. — 5 K 



