184 



CAEDUACEAE. 



Ray-flowers with white or colored (not yellow) 

 corollas. 

 Bracts of the involucre in 3-many series. 



Ray-flowers few ; ligules relatively short and 



broad : bracts of the involucre leathery. 13. SERicocARPt-s. 



Ray-flowers numerous ; ligules relatively long 

 and narrow : bracts of the involucre mainly 

 herbaceous. 14. Aster. 



Bracts of the involucre in 1 or 2 series. 



Kay-flowers with ligules longer than the diam- 

 eter of the disk. 15. Erigeeox. 

 Ray-flowers with ligules shorter than the 



diameter of the disk. 16. Leptilox 



Ray-flowers wanting: plants dioecious. 17.' Bacchaeis 



Tbibh IV. IXULEAE. 

 Heads clustered : bracts of the involucre scarious, her- 

 baceous. 

 Bracts of the involucre broad, mainly persistent. 

 Bracts of the involucre narrow, raainly deciduous. 

 Heads scattered : bracts of the involucre rigid. 



Tribe V. HELIAXTHEAE. 

 Disk-flowers perfect, but not fruit-producing. 

 Achenes short and thick, not flattened. 

 Achenes markedly flattened. 



Ray-flowers with relatively large conspicuous 



ligules. 

 Ray-flowers with inconspicuous ligules, the heads 

 apparently discoid. 

 Disk-flowers fruit-producing. 



Pappus a mere crown or cap, or of few teeth, awns 

 or bristles. 

 Achenes, at least those of the disk, not com- 

 pressed (except in Pliiicth iiku) : bractlets 

 mostly concave and clasping. 

 Bractlets of the receptacle mere chaffy awns 



or bristles. 

 Bractlets of the receptacle concave or clasping. 

 Ray-flowers wanting : bracts of the invo- 

 lucre dry. 

 Ray-flowers present : bracts of the invo- 

 lucre herbaceous. 

 Achenes of the disk neither sharp-edged, 

 margined nor winged. 

 Ray-flowers fruit-producing. 



Achenes turgid, those of the disk 

 obtusely, if at all angled : stems 

 herbaceous. 

 Achenes acutely 4-angled, or 3- 

 angled In the ray : stems woody. 

 Ray-flowers not fruit-producing. 

 Achenes of the disk thin-edged, mar- 

 gined or winged. 

 Achenes markedly flattened parallel to the invo- 

 lucral bracts. 

 Pappus of 2 flmbriolate au-ns, scales or teeth, 



or a mere border or wanting. 

 Pappus of 2-6 awns or teeth, upwardly or 

 downwardly barlied or hispid. 

 Pappus of numerous scales. 



Receptacle honeycombed by the concretion of the 



bractlets. 

 Receptacle with distinct bractlets. 



18. PLtCHEA. 



lf>. Pterocauloji. 

 20. Sach.sia. 



21. Acaxthospermum. 



22. Berlaxdieea. 



23. Parthexium. 



24. Verbesixa. 



25. Melaxthera. 



26. Wedelia. 



27. BoRRicniA. 

 2.S. Heliaxthus. 



29. Pjiaethi sA. 



30. Coeeop.sis. 



31. Bidexs. 



32. Actixospermum. 



33. Tridax. 



Tribe VI. HELENIEAE. 

 Plant-tissues without oil-glands. 



Bracts of the involucre petal-like, the margins and 



tips scarious. 34. Polypterir. 



Bracts of the involucre narrow, herbaceous. 

 Bracts of the involucre appressed. 



Achenes 4-angled : disk-corollas with a long 



throat and a short tul)e ; lobes long. 35. Palafoxia. 



Achenes 8-10-ribbed : disk-corollas with a short 



