CLASS XIX. ORDER 11. 323 



the margin very numerous and fine, pale blue or purplish. Road 

 sides, flowering in July and August. — Perennial. 



§ Subgenus C^notus. Calyx oblong; ray minute; down simple. 

 Erigeron Canadense. L. Annual Flea Bane. 



Stem hairy; flowers panicled; leaves lanceolate, 

 lower ones serrate. Sm. 



One of the most hardy and common annual weeds. It propa- 

 gates itself rapidly, and since the discovery of America, has 

 been introduced, and spread through most countries in Europe. 

 Stem erect, furrowed, very hairy, branching. Leaves linear- 

 lanceolate, edges rough and ciliate. Flowers small, of no beauty, 

 very numerous, arranged in a sort of racemes on the branches. 

 Calyxes cylindrical, longer than they are wide, somewhat imbri- 

 cate. Ray very short and obscure, white, crowded, erect. In 

 pastures, road sides, and cultivated grounds, varying in height 

 from one to four feet, according to the soil. — August. 



345. TUSSILAGO. 



TUSSILAGO FRIGIDA. L. Wild CoW S foot. 



Leaves triangular-heart shaped, unequally toothed, 

 downy underneath. 

 Syn. Nardosmia fkigida. Hooker. 



Found in mountain woods, Vermont and Massachusetts, pro- 

 ducing a corymb of white flowers with a pale purplish disc. 



346. SOLIDAGO.* 



SoLiDAGo lanceolata. L. Spear leaved Golden Rod. 

 Stem glabrous, branching ; leaves lance-linear, en- 



* This genus is exceedingly abundant in the United States, and 

 with the genus .^ster predominates in August and September over all 

 other vegetables then in flower. Among the species there are a vast 

 variety of hybrids and subspecies which the labors of botanists have 

 not yet been able to reduce under permanent cliaracters, though 

 names without number have been applied to fugitive varieties. The 

 single species found in Great Britain is acknowledged to be one of 

 the most difficult plants " to define or understand." The same re- 



