824 PATAGONIAN EXPEDITIONS I BOTANY. 



VERBESINA AUSTRALIS (Hook & Arn.) Baker. (Ximenesia microptera DC.) 



Annual, with stems not winged. Leaves alternate, dorsally white- 

 tomentose ; lower leaves deltoid-petiolate, sharply serrate, the upper ses- 

 sile, basi-auriculate. Heads few, lax-corymbose. Ligules 10-12, large, 

 showy. Achenes narrowly winged ; awns short. 



(Argentina, etc.); N. Patagon.; common along Rio Negro. 



40. THELESPERMA Less. 



Glabrous herbs, with opposite, linear or finely dissected leaves and long- 

 peduncled, mid-sized heads of both tubular and radiate flowers, or rayless. 

 Involucre broad, 2-seriate, the outer scales short, spreading, the inner 

 connate half-way, their tips scarious. Receptacle chaffy. Ray-flowers 

 neuter, yellow. Anthers basiobtuse. Style-branches obtuse. Achenes 

 papillose on the back, wingless. Pappus of 2 retrorsely hispid awns or 

 none. 



Species 7, Amer., from southern United States to Patagon. 



i. T. MEGAPOTAMICUM O. Ktze. (Spr. sub Bidens]. 



Leaves all bipinnatifid, linear-filiform, glabrous. Heads mostly in 

 pairs, peduncled, erect, discoid. Involucre colored, as long as the disk. 

 Achenes ? 



(Brazil ; Argentina) ; N. Patagon., common along Rio Negro. 



2. T. SCABIOSOIDES LeSS. 



Herb from woody root, 60 cm. high, of habit of Scabiosa columbaria 

 gramuntia DC. Glabrous, with many stems which are rigid, divided from 

 below into a subtrichotomous panicle, with spreading branches and long 

 peduncles. Leaves decussate, at least below, finely dissected ; their seg- 

 ments linear to 16 mm. long; passing to upper, simple, sessile, linear 

 leaves. Heads erect, homogamous. (Fig. in Eng. & Prantl, iv, 5, p. 

 240, E-F.) 



(Uruguay, etc.) ; N. Patagon., by Rio Negro. 



41. MADIA Molin. Tarweed. 



Erect annuals, with entire leaves, and glandular, often scented pubes- 

 cence. Heads mostly radiate and heterogamous. Involucral scales i- 



