856 COMPOSITAE 



17A. Style-branches nearly terete, obtuse, short-papillose; leaves opposite or verticillate. 



18A. Anthers appendaged at apex; pappus-bristles setose 15. Eupatorium 



18B. Anthers without appendage at apex; pappus-bristles clavate 16. Adenostemma 



17B. Style-branches flat, smooth, truncate or appendaged at apex. 



19A. Style-branches with a lanceolate or deltoid hairy appendage at apex; leaves alternate. 

 20A. Ligulate corollas broad, petallike, spreading. 



21A. Ligulate corollas yellow 17. Solidago 



21B. Ligulate corollas white or reddish. 



22A. Ligulate florets fewer than the tubular florets; heads more than 1 cm. wide. 



23A. Pappus absent 18. Gymnaster 



23B. Pappus present. 



24A. Pappus bristles less than 1 mm. long, lacerate 19. Kalimeris 



24B. Pappus more than 2 mm. long, at least of the tubular florets. 



25A. Pappus dimorphic, of the tubular florets setose, of the ligulate florets very short and lacerate. 



20. Heteropapptis 

 25B. Pappus all bristlelike. 



26A. Involucral bracts narrow, in a few series, not definitely imbricate; ligulate florets in 2 or more series, 



narrow 21. Erigeron 



26B. Involucral bracts broadly imbricate; heads less than 1 cm. wide; ligulate florets in 1 or 2 series. 22. Aster 

 22B. Ligulate florets more numerous than the tubular florets. 



27A. Achenes not beaked 23. Myriactis 



27B. Achenes beaked. 



28A. Stems erect, branched, many-leaved 24. Rhynchospermum 



28B. Stems scapiform, few-leaved 25. Lagenophora 



20B. Ligulate corollas filiform, long or short, erect. 



29A. Pappus well-developed 26. Conyza 



29B. Pappus wanting 27. Dichrocephala 



19B. Style-branches truncate or rarely with very short or narrow appendages. 

 30A. Pappus-bristles elongate, well developed. 



31A. Plants usually dioecious; bisexual florets with a short bifid style; leaves all radical, those of the inflorescence scale- 

 like 28. Petasites 



31B. Plants hermaphroditic; leaves radical and cauline. 



32A. Annuals; leaves alternate; corollas all tubular and fertile 29. Erechtites 



32B. Perennials; leaves opposite. 



33A. Heads usually with ligulate florets 30. Arnica 



33B. Heads all discoid; leaves alternate. 



34A. Style-branches appendaged, short-strigose at apex 31. Emilia 



34B. Style-branches truncate, penicillate, or obtuse at apex. 



35A. Leaves very thick, involute in the early stages, the lower and radical with a short sheath at base; achenes 



densely hairy 32. Farfugium 



35B. Leaves membranous, revolute in the early stages. 



36A. Radical and cauline leaves with a short sheath at base. 



37A. Style-branches obtuse; heads with ligulate florets; involucral bracts 1 -seriate but of two forms. 



33. Ligularia 

 37B. Style-branches truncate; heads without ligulate florets. 



38A. Achenes beaked; involucres with caliculus at base; corollas yellow 34. Miricacalia 



38B. Achenes not beaked; involucres without caliculus (rarely caliculate); corollas whitish. . . 35. Cacalia 

 36B. Leaves not sheathed at base. 



39A. Corollas yellow; ligulate corollas present or rarely absent 36. Senecio 



39B. Corollas whitish or reddish; ligulate corollas absent 37. Syneilesis 



SOB. Pappus absent or very short, crownlike, scalelike, or awnlike. 

 40A. Involucral bracts scarious on margin. 



41A. Receptacles chaffy; leaves toothed or bipinnate 38. Achillea 



41B. Receptacles naked. 



42A. Ligulate florets more numerous than the disc florets; annuals with small axillary heads 39. Centipeda 



42B. Ligulate florets fewer than the disc florets. 

 43A. Heads erect; appendage of anthers oblong. 



44A. Receptacle conical; achenes ribless on back, 3-ribbed in front 40. Matricaria 



44B. Receptacle convex, hemispheric, sometimes flat; achenes striate 41. Chrysanthemum 



43B. Heads nodding; appendage of anthers lanceolate; pistillate corollas tubular 42. Artemisia 



40B. Involucral bracts herbaceous, green. 



45A. Tubular florets sterile; receptacle not chaffy 43. Adenocaulon 



45B. Tubular florets fertile; receptacle chaffy. 



46A. Achenes of the ligulate florets 3-angled, or of the tubular florets laterally flattened. 



47A. Involucral bracts spreading, glandular-pubescent; scales of receptacle enveloping or surrounding the achene. 



44. Siegesbeckia 

 47B. Involucral bracts appressed; scales of receptacle folded. 



48A. Involucral bracts 2-seriate; scales of receptacle very narrow; annuals 45. Eclipta 



48B. Involucral bracts 1-seriate; scales on receptacle convex or folded; perennials 46. Wedelia 



46B. Achenes more or less dorsally flattened. 



