262 YELLOW RED-POLL WARBLER. 



Individuals of both sexes exhibit considerable difference in the tints 

 of the plumage, at different ages and in different seasons. 



Helenidm QUABRiDENTATUM, Willd. Sp. PI. vol. iii. p. 2121, Pursli, Flor. Amer. 

 Sept. voL ii. p. 560. — Stngenesia Polygamia Superflua. CompositjE, 

 Juss. 



From three to four feet high, with the stem branched, the leaves de- 

 current, the lower subpinnatifid, the upper lanceolate, undivided, smooth ; 

 the corollas of the disk four-toothed. This plant springs up spontane- 

 ously over aU the abandoned lands of Louisiana, and is very difficult to 

 be extirpated. It is often gathered and burnt, to prevent the musquitoes 

 from entering houses. 



