ARTICLE XX. ^^'7 





Descriptions of new Species and Genera of Plmits in the natural Order of the 

 CompositjE, collected in a Tour across the Continent to the Pacific, a Residence 

 in Oregon, and a Visit to the Sandrvich Islands and Upper California, during 

 the Years 1834 and 1835. By Thomas Nuttall Read Oct. 2, 1840. 



Tribe I. VERNONIACE.E. 



Vernonia ^sphceroidea, pubescent; leaves lanceolate, serrate, beneath vil- 

 lous; corymb compound, many-flowered, flowers small; involucrum subglo- 

 bose, scales short and equal, tomentose and reflected. — Hab. Prairies of Ar- 

 kansas. 



Obs. — Remarkable for the reflection of the scales of the involucrum, which 

 are all short, equal, and densely tomentose at the base and margins. * 



Vernonia Arhansana, (Decand.) nearly smooth and herbaceous; leaves 

 linear-lanceolate, very long, serrulate; corymb simple; flowers large, nearly all 

 pedunculate, hemispherical; leaves of the involucrum lanceolate, terminating 

 in very long, filiform, leafy, and spreading points. — Hab. Plains of Arkansas, 

 near Red River. 



Obs. — Remarkable for the great size of the heads of flowers, more than twice 

 as large as in any other of our species, and also singular in the great length of 

 the squamose points of the leaflets of the involucrum, which are a little pubes- 

 cent. The leaves are very long, narrow, and smooth. Achenium somewhat 

 pubescent. Pappus double, as usual. 



