ASTER FAMILY 245 



s. Flowers yellow 



(r) Heads narrow, cylindric, 



few-flowered 



h. Bracts of involucre in dis- 

 tinct vertical rows CHRYSOTHAMNUS 

 i. Bracts of involucre not in 



vertical rows ISOCOMA 



(s) Heads broad, many-flow- 

 ered 

 h. Bracts of involucre in 2- 



3 rows HAPLOPAPPUS 



i. Bracts in 1 row 



(h) Leaves opposite ARNICA 



(i) Leaves alternate SENECIO 



-y. Pappus not hairy, but of scales, awns or 



lacking 



(x) Receptacle with chaffy scales among 

 the flowers; pappus usually of 2- 

 6 awns 



m. Bracts of involucre separate BIDENS 



n. Inner bracts of involucre united in- 

 to a cup THELESPERMA 

 (y) Receptacle not chaffy 

 m. Pappus a crown, or none 



(m) Pappus a fringed crown; 



leaves 'opposite, long-tailed PERICOME 

 (n) Pappus a low, entire crown or 



none; leaves dissected 



r. Pappus usually a crown TANACETUM 



s. Pappus usually none MATRICARIA 



n. Pappus of scales or awns 

 (m) Leaves entire or toothed 

 r. Leaves entire, mostly basal; 

 involucre not sticky, the 

 bracts in 2-3 rows ACTINELLA 



s. Leaves toothed, on the stem ; 

 involucre sticky, the bracts 

 in several rows GRINDELIA 



(n) Leaves parted or dissected 

 r. Flowers yellow BAHIA 



s. Flowers yellowish or whitish 



