Plants Collected in Pay^aguay. 149 



blossoms from November to April, and, in fact, even in July, in the 

 depth of winter, specimens in flower could be obtained by careful 

 search among the grass. Stems often creeping and rooting. 



Bidens pilosa, L., Sp. PL, 832. 



Asuncion (208); Pilcomayo River (959). November-March. 



This plant fills the waste grounds and old fields around the city, 

 and is as great a nuisance as our own Spanish Needles. I found 

 specimens on the Pilcomayo River banks nearly 3 m. in height. 

 This was distributed as B. leucantha, Willd. 



Isostigma Vailiana, Britton, n. sp. 



Perennial, glabrous, stem prostrate or ascending, 10-15 cm. long. Leaves 

 coriaceous, narrowly cuneate at the base, laciniately 3-7 toothed at the apex, 

 4-7 cm. long, 8-12 mm. wide ; peduncles erect, usually single and terminal, 

 sometimes with an additional one or two lateral ones, 10-20 cm. high ; heads 

 discoid, 1-1^ cm. broad ; involucre campanulate ; scales in 3 rows, ovate, 

 obtusish ; flowers purple ; corolla rather deeply 4-lobed ; achenia flat, linear, 

 slightly narrowed below, with two divergent, subulate awns at the apex ; 

 paleae linear, membranaceous, nearly as long as the achenia. 



Limpio (734). May. Differs from other species of the genus in 

 its 4-lobed corolla, all the described ones having 5-toothed corollas. 



This rare plant, with large handsome dark purple heads, is named 

 in honor of Miss Anna Murray Yail, by whose kindly assistance 

 the work of arranging my Paraguay collection has been greatly 

 facilitated. 



Calea clematidea, Baker, 1. c, 262. 

 Asuncion (766). July. = Balansa 845. 



Calea uniflora, Less., Linnsea, 1830, p. 159. 



Caballero (514). January. = Balansa 812. 



This genus, which does not occur in the United States, is distin- 

 guished by having sagittate anthers, chaffy receptacles, and narrow, 

 angled achenia crowned with a pappus of 5-20 chaflF-like scales. 

 No. 766 is very branching, the stems sufi*ruticose, 4 or 5 dm. high. 

 Leaves opposite, ovate, crenate-dentate, with truncate or subcordate 

 base, pubescent, rugose beneath, the blades 3-4 cm. long, 1^-2 cm. 

 wide, on short downy petioles. Flowers yellow in numerous small 

 heads. Scales of the involucre broad, obtuse, appressed, imbricated, 

 yellowish-green, striped, in 3 or 4 rows. Rays 4, with 3 or 4 teeth, 



