SOLIDAGO TANACETUM 295 



x. Bracts of the involucre sharp-pointed to 



tapering-pointed S. multiradidta 



y. Bracts of the involucre obtuse or 



rounded S. humilis 



b. Stems and leaves hairy, at least the leaves 



(1) Leaves lanceolate, soft-hairy; stems 2-6 



ft. high; heads 3-4 mm. high; rays 9-15 S. canadensis 



(2) Leaves oblanceolate, spatulate to elliptic 



or ovate, rough-hairy or gray-hairy; 

 heads 4-6 mm. high ; rays 5-9 



x. Leaves oblanceolate to spatulate, rough- 

 hairy ,S\ nemordlis 



y. Leaves elliptic to ovate or obovate, 



densely gray-hairy S\ mollis 



SONCHUS Linne 1753 Sow THISTLE 

 (The Greek name) 



Heads with yellow perfect strap-flowers, achenes linear to oval, some- 

 what flattened, ribbed, not beaked, pappus of white hair-like bristles; re- 

 ceptacle flat, without chaff, involucre ovoid to bell-shaped, the bracts im- 

 bricated in 2 or more rows ; heads in corymbs or panicles ; leaves alternate, 

 usually clasping, entire to pinnatifid and prickly-margined; annual or 

 perennial. 



1. Involucre 20-25 mm. high, sticky-hairy; heads 



1-2 in. wide 5. arvensis 



2. Involucre 12-16 mm. high, smooth ; heads an inch 



or less wide 



a. Basal ears of the clasping leaves acute; 



achenes striate, wrinkled crosswise v$\ olerdcews 



b. Ears of the leaves rounded ; achenes ribbed, 



not wrinkled crosswise S. dsper 



TANACETUM Linne 1753 TANSY 

 (Latinized from Fr. tanasie, Gr. athanasia, immortality) 



Heads usually rayless, marginal flowers yellow, pistillate, sometimes 

 forming short rays, disk-flowers yellow, perfect, achenes 5-angled or ribbed, 

 pappus none or a short crown; receptacle flat or convex, without chaff, 

 involucre hemispheric to bell-shaped, bracts imbricated in several rows; 

 heads in corymbs ; leaves alternate, 1-3-pinnately divided or dissected ; 

 perennial. 



