146 



CAEDUACEAE, 



Teibh IV. INULEAE. 



Heads clustered : bracts of the Involucre scarious, her- 

 baceous. 



Bracts of the involucre broad, mainly persistent. 



Bracts of the involucre narrow, mainly deciduous. 

 Heads scattered : bracts of the involucre rigid. 



Tkibb V. HELIANTHEAE. 



Disk-flowers perfect, but not fruit-producing. 

 Disk-flowers fruit-producing. 



I'appus a mere crown or cap, or of few teeth, awus 

 or bristles. 

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

 pressed (except in Phut thuaa) : bractlets 

 mostly concave and clasping. 

 Ray-flowers wanting : bracts of the involucre 



dry. 

 Ray-flowers present : bracts of the involucre 

 herbaceous. 

 Achenes of the disk neither sharp-edged, 

 margined nor winged. 

 Ray-flowers not fruit-producing. 

 Ray-flowers fruit-producing. 

 Achenes of the disk thin-edged, margined or 

 winged. 

 Achenes markedly flattened parallel to the invo- 

 lucral bracts. 

 Pappus of 2 flmbriolate awms, scales or teeth, 



or a mere border or wanting. 

 Tappus of 2-6 awns or teeth, upwardly or 

 downwardly barbed or hispid. 

 Achene beakless : ray-flowers with yellow or 



white ligules, or wanting. 

 Achene beaked : ray-flowers with purple or 

 rose ligules. 

 Pappus of numerous scales. 



TitiBE VI. HELENIEAE. 



Plant-tissues without oil-glands. 



Plant-tissues, especially the leaves and bracts of the 

 involucre, with oil-glands. 



11. Plcchea. 



12. i'terocaulox. 

 VA. Sachsia. 



14. Parthexium. 



15. Melaxthera. 



10. BORRICHIA. 

 17. riELIANTIirS. 



IS. XlMENESIA. 



I'J. Coreopsis. 



20. BiDENS. 



21. Cosmos. 



22. Tridax. 



23. Flaveria. 



2 1. I'ectis. 



Tribb VII. SENECIONEAE. 



Disk-flowers perfect : marginal flowers pistillate. 

 Disk-flowers and marginal flowers perfect. 



25. Ereciitites. 



26. EiuHA. 



Tribe VIII. 

 Plants with spine-margined leaves. 



CVNAREAE. 



IT. CiRSH M. 



1. VERNONIA L. Caulescent herbs. Leaves alternate: blades mostly 

 toothed. Heads not involucrate. Corolla-lobes lanceolate. Anther-appendages 

 lanceolate to oblong. Pappus double, the outer series of scales or stout bristles, 

 the inner of numerous capillary bristles. — Iroxweed. 



Achenes rihlied : corollas 8-12 mm. long. 



I'.ladi's of the upper cauline leaves narrowly linear, entire: inner involucral bracts 



."i (i mm. long. 1. T. lilodfjcttii. 

 Blades of the upper cauline leaves not narrowly linear, toothed : 



inner involucral bracts 3-4 mm. long. 2. T'. gigantca. 



Achenes terete or nearly so : corollas about 2 mm. long. 3. V. eincrca. 



1. V. Blodgettii Small. Stems 2-8 dm. tall: leaf-blades oblong to linear, 2-4.5 

 cm. long, t'litire: involucres (i-7 mm. high; inner bracts oblong or ovate-oblong, 

 acute or acuminate: corolla purple. — Pinelands, L. keys. — [E. K.] 



2. V. gigantea (Walt.) Britton. Stem 9-2o dm. tall: leaf-blades linear to 

 oblong or elliptic, 8-SO cm. long, shar])ly serrate: involucres 4-5 mm. high; 

 inner bracts narrowly oblong or linear-oblong, obtuse or mucronate. — Ham- 

 mocks, Key West. 



