144 SELECTED WESTERN FLORA 



13. SENECIO. Groundsel, Ragwort. 



Heads many-flowered, usually radiate; ray-flowers, when pres- 

 ent, pistillate; involucre with the main bracts in one row, usually 

 with some shorter outer ones at the base; receptacle mostly flat 

 and naked, often honeycombed; pappus of numerous slender soft 

 white bristles. Annual or perennial, sometimes woolly herbs with 

 alternate leaves, often much reduced, and yellow flowers. 



1. S. paliistris, Hook. 



Annual, woolly with loose hairs, stem erect, stout, 6-24 in. high; leaves 

 lanceolate, irregularly toothed or cut, the upper clasping; rays 15-20, pale 

 yellow; heads In a corymb; pappus long, white. Wet places, mostly about 

 the edges of ponds, Man.-Alta. 



2. S. aureus, L. 



Perennial; stem erect, rather slender, 1-2 ft. high; slightly hairy at first, 

 becoming glabrous ; lower leaves petioled, broadly ovate or orbicular, dent- 

 ate; stem leaves pinnately cut, the upper sessile and much reduced; heads 

 radiate, in a cyme or corymb. Moist grassy places, Man.-Alta. 



3. S. balsamitse, Muhl. 



Resembling the preceding, but the lower leaves oblong to lanceolate, 

 sharply dentate or serrate. (S. aureus, var. balsamitse T. and G.) Moist 

 prairies, Alta. 



4. S. cSnus, Hook. 



Rather low, 6-12 in. high, slender, usually tufted, white-tomentose up to 

 the flowers; lower leaves oblong or spatulate, sparingly, if at all, toothed, 

 white; stem leaves often pinnatifid, the upper much reduced and often 

 clasping; rays about 8. N. Sask. and Alta. 



14. TANACilTUM. Tansy. 



Heads discoid; marginal flowers fertile, their corollas 2-5-toothed; 

 disk-flowers fertile, 5-toothed ; achenes 5-cornered ; pappus wanting 

 or a very slight crown. Erect, strong-smelling perennial herbs 

 with 1-3 pinnately divided leaves, and numerous small heads of 

 yellow flowers arranged in corymbs. 



1. T. vulgare, L. 



Stout, 1-3 ft. high, branching above; leaves 2-pinnate the lobes deeply 

 pinnatifid; marginal flowers with very short 3-toothed rays. A cparse, 

 strong-smelling, introduced herb sometimes growing in bunches about 

 towns. 



