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(y) Involucral bracts in 2-several rows 

 m. Heads broad, many -flowered ; rays 

 many 

 (m) Pappus bristles in 2 rows, the 



outer much shorter Chrysopsis 



(n) Pappus bristles equal, in 1 row Haplopappus 

 n. Heads narrow, few-flowered ; rays 



3-20 Solidago 



(b) Rays not yellow 

 x. Pappus of many hair-like bristles 



(x) Involucral scales usually in 1-2 



rows ; rays usually many, narrow 



m. Rays longer than the width of the 



disk Erigeron 



n. Rays tiny, not longer than the 



width of the disk Leptilum 



(y) Involucral scales usually in several 

 rows ; rays broad 

 m. Bracts in 2-5 rows, not spreading 



or reflexed as a rule Aster 



n. Bracts in many rows, mostly 



spreading or reflexed Machaeranthgka 



y. Pappus of a few hair-like bristles or 



scales or both Townsendia 



t 2) Pappus not hairy, but of scales, awns, etc., 

 or none 

 (a) Rays yellow 

 x. Ray 1 ; leaves opposite ; pappus none Flaveria 

 y. Rays more than 1 

 (x) Achenes 4-angled 

 m. Plants permanently densely woolly Eriophyllum 

 n. Plants not densely woolly, or only 

 when young 

 (m) Plants sticky-hairy Hulsea 



(n) Plants not sticky-hairy 

 r. Leaves entire Platyschkuhkia 



s. Leaves parted or divided Bahia 



(y) Achenes 5-10 ribbed 

 m. Receptacle with bristles among the 

 disk-flowers; pappus of 5-10 

 pointed scales Gaillardia 



