146 



CAEDUACEAE. 



TKIBH IV. INULEAE. 



Heads clustered : bracts of the Involucre scarlous, her- 

 baceous. 



Bracts of the Involucre broad, mainly persistent. 

 Bracts of the involucre narrow, mainly deciduous. 

 Heads scattered : bracts of the involucre rigid. 



11. PLUCHEA. 



12. PTEBOCAULOX. 



13. SACHSIA. 



TRIBE V. HELIANTHEAE. 



Disk-flowers perfect, but not fruit-producing. 14. PARTHEXICM. 



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 Phacthusa) : bractlets 

 mostly concave and clasping. 

 Ray-flowers wanting : bracts of the involucre 



dry. 15. MELAXTHERA. 



Ray-flowers present : bracts of the involucre 



herbaceous. 

 Achenes of the disk neither sharp-edged, 



margined nor winged. 



Ray-flowers not fruit-producing. 16. BOBRICHIA. 



Ray-flowers fruit-producing. 17. HELIAXTHUS. 



Achenes of the disk thin-edged, margined or 



winged. 18. XIMEXESIA. 



Achenes markedly flattened parallel to the invo- 



lucral bracts. 

 Pappus of 2 flmbriolate awns, scales or teeth, 



or a mere border or wanting. 19. COREOPSIS. 



Pappus of 2-6 awns or teeth, upwardly or 



downwardly barbed or hispid. 

 Achene beakless : ray-flowers with yellow or 



white ligules, or wanting. 20. BIDEXS. 



Achene beaked : ray-flowers with purple or 



rose ligules. 21. COSMOS. 



Pappus of numerous scales. 22. TRIDAX. 



TRIBE VI. HELENIEAE. 



Plant-tissues without oil-glands. 23. FLAVERIA. 



Plant-tissues, especially the leaves and bracts of the 



involucre, with oil-glands. 24. PECTIS. 



TRIBH VII. SENECIONEAE. 



Disk-flowers perfect : marginal flowers pistillate. 25. ERECHTITES. 



Disk-flowers and marginal flowers perfect. 26. EMILIA. 



TRIBH VIII. CYNAREAE. 

 Plants with spine-margined leaves. 



27. CIRSIIM. 



1. VEENONIA 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 ribbed : corollas 8-12 mm. long. 



Blades of the upper cauline leaves narrowly linear, entire : inner involucral bracts 

 5-6 mm. long. 1. V. Blodgettii. 



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



inner involucral bracts 3-4 mm. long. 2. V. giganttn. 



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



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

 cm. long, entire: involucres 6-7 mm. high; inner bracts oblong or ovate-oblong, 

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



2. V. gigantea (Walt.) Britton. Stem 9-25 dm. tall: leaf -blades linear to 

 oblong or elliptic, 8-30 cm. long, sharply serrate: involucres 4-5 mm. high; 

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

 mocks, Key West. 



