COMPOSITAE. 915 



Leaves entire, or toothed, not bristly-serrate. 



Leaves narrow, coriaceous, evergreen, entire ; low western undershrubs. 



20. Stenotus. 

 Annual or perennial herbs; leaves not evergreen. 



Pappus-bristles unequal ; heads loosely panicled ; annual. 



21. Isopappus. 

 Pappus-bristles equal; heads variously clustered; perennial herbs. 



Receptacle alveolate; rays mostly not more numerous than the disk-flowers. 



22. Solidago. 

 Receptacle fimbrillate; rays more numerous than the disk-flowers; heads 



corymbose-paniculate. 23. Euthamia, 



b. Lower and basal leaves cordate; pappus-bristles shorter than the achene. 



24. Brachychaeta. 



B. Ray-flowers present, not yellow in any of our species. 



* Pappus a mere crown, or of a few awns or bristles, or wanting, never of numerous 



capillary bristles 

 i. Receptacle conic. 

 Outer bracts of the involucre shorter than the inner; achenes prismatic. 



25. Aphanostephus. 

 Bracts of the involucre all about equal ; achenes flattened. 26. Bellis. 



2. Receptacle flat, or somewhat convex. 

 Achenes of the disk-flowers compressed, of the ray-flowers 3-angled; perennial herbs 



with large heads. 27. Townsendia. 



Achenes fusiform, terete; annual herbs with small heads. 28. Chaetopappa. 



Achenes obovate, flattened, with thickened or winged margins ; perennials. 



29. Boltonia, 

 * Pappus of numerous capillary bristles. 



I. Pappus a single series of capillary bristles; sometimes with an outer series 



of shorter ones. 



a. Bracts of the involucre in 2 to many series. 

 Bracts mostly in 2-5 series; teeth or lobes of the leaves not bristle-tipped. 



Involucre narrow, its bracts firm ; rays few, white. 30. Sericocarpus. 



Involucre turbinate to hemispheric, bracts mostly thin; rays usually numerous, white 

 to purple. 



Disk-flowers turning red, purple, or brown. 31. Aster. 



Disk-flowers permanently white; leaves subulate to spatulate, crowded, rigid. 



32. Leucelene. 

 Involucre turbinate; rays not exceeding the mature pappus, or none. 



33. Brachyactis. 

 Bracts in many series; teeth or lobes of the leaves bristle-tipped in our species. 



34. Machaeranthera. 

 b. Bracts of the involucre in only i or 2 series, very narrow ; heads mostly 



long-peduncled. 



Rays longer than the diameter of the disk. 35. Erigeron. 



Rays not longer than the diameter of the disk; heads very small, panicled. 



36. Leptilon. 



2. Pappus distinctly double, the inner bristles long, the outer shorter. 

 Leaves lanceolate, ovate, or obovate; rays white. 37. Doellingeria. 



Leaves narrowly linear; rays violet. 38. lanactis. 



C. Ray-flowers none; dioecious shrubs; pappus capillary. 39- Baccharis. 

 Tribe 4. INULEAE. 



* Heads small, rays none; flowers white or whitish. 



i. Receptacle chaffy. 



Receptacle convex; pappus none. 40. Filago. 



Receptacle subulate; pappus of the inner flowers of rough capillary bristles. 



41. Gifola. 

 a. Receptacle naked. 



a. Pappus, at least that of pistillate flowers, of capillary bristles. 

 Bracts of the involucre notscarious; plants pubescent or glabrous, not woolly. 



42. Pluchea. 

 Bracts of the involucre scarious, mostly white or pink; plants woolly. 



Plants dioecious, or polygamo-dioecious. 



Pappus-bristles of s'taminate flowers thickened above. 43. Antennaria. 

 Pappus-bristles not thickened; stem leafy. 44- Anaphalis, 



