343 



COMPOSITAE. VOL. III. 



Annual herbs; disk-flowers sterile. n. Amphiachyris. 



Heads large, showy; leaves oblong to lanceolate, spinulose-dentate. 12. Grindelia. 



** Pappus of either the radiate or tubular flowers, or both, of numerous capillary bristles, with or without 

 an outer series of shorter ones, or of scales. 



t Pappus, at least of the disk- flowers, double, an inner series of capillary bristles, and an outer one 



of scales or short bristles ; heads large. 

 Achenes of the ray-flowers thick, the pappus obsolete, or of a few caducous bristles ; achenes of the 



disk-flowers flat. 13. Heterotheca. 



Achenes of both ray-flowers and disk-flowers flattened. 14. Chrysopsis. 



tt Pappus wholly of capillary bristles. 

 i. Heads wholly of disk-flowers (in our species) ; rays none; leaves narrowly linear. 



a. Perennial herbs; style-tips not exserted; eastern. 15. Chondrophora. 



b. Shrubs ; style-tips mostly exserted ; western. 



Involucral bracts gradually narrowed to the tip, keeled, chartaceous. 16. Chrysothamnus. 



Involucral bracts cuspidate, flat, herbaceous. 17. Oonopsis. 



2. Heads with both ray-flowers and disk-flowers (in our species). 

 a. None of the leaves cordate ; pappus mostly as long as the achene, or longer. 

 Leaves bristly-serrate or pinnatifid. 



Achenes glabrous ; pappus-bristles deciduous. 18. Prionopsis. 



Achenes white-tomentose ; pappus-bristles persistent. 19. Sideranthus. 



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. Aphahostephus. 



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 mostly in 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. lonactis. 



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



39. Baccharis. 



Tribe 4. INULEAE. 



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



1. Receptacle chaffy. 



Receptacle convex ; pappus none. 40. Filago. 



Receptacle subulate; pappus of the inner flowers of rough capillary bristles. 41. Gifola. 



2. Receptacle naked. 



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



Bracts of the involucre not scarious ; 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 staminate flowers thickened above. 43. Antennaria. 



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



Plants not dioecious ; flowers all fertile. 45. Gnaphalium. 



b. Pappus none ; leaves broad, alternate, woolly beneath. 



46. Adenocaulon. 

 ** Heads large ; ray-flowers yellow. 47. Inula. 



