ASTER FAMILY 24; 



b 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 Isocojea 



(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 

 1 acking 

 (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 

 Cm) 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 vellowish or whitHi 



