310 COMPOSITAE 



Tribe IV. INULEAE. 

 Ray-flowers wanting : disk-flowers, at least, with white or whitish corollas : 

 heads relatively small. i 



Receptacle chaffy. 19. Gifola. 



Receptacle naked. 

 Involucre of herbaceous bracts : plants more or less pubescent, not woolly. 



20. Pluchea. 

 Involucre of scarious bracts : plants woolly. 

 Plants with dioecious or polygamo-dioecious flowers. 



Pappus-bristles of the staminate flowers thickened above : stems 



mainly creeping. 21. Antennaria. 



Pappus-bristles not thickened : stems erect. 22. Anaphalis. 

 Plants not dioecious : flowers all fruit-producing. 23. Gnaphalium. 

 Ray-flowers present and yellow : heads relatively large. 24. Inula. 



Tribe V. HEUANTHEAE. 

 Disk-flowers perfect, but not fruit-producing. 

 Achenes thick or turgid : pappus wanting. 25. Polymnia. 



Achenes flattened : pappus present, sometimes obsolete. 

 Ray-flowers in 2 or 3 series : achenes falling away free. 



26. SiLPHIUM. 



Ray-flowers in i series : achenes adnate to 2 or 3 bractlets and falling away 

 with them. 27. Chrysogonum. 



Disk-flowers fruit-producing. 

 Corollas of the ray-flowers persistent on the achenes. 28. Heliopsis. 

 Corollas of the ray-flowers deciduous or wanting. 



Pappus a cup or a crown, or of few teeth, awns or bristles. 

 Achenes, at least those of the disk-flowers, not flattened (except in Ver- 

 besina): bractlets of the receptacle mostly concave or clasping. 

 Bractlets of the receptacle subulate or bristle-like : ray-flowers with 



white ligules. 29. Eclipta. 



Bractlets of the receptacle broad. 

 Receptacle conic. 30. Rudbeckia. 



Receptacle flat or merely convex. 

 Achenes scarcelj- flattened, neither winged nor margined. 



31. Helianthus. 

 Achenes of the disk-flowers flattened, margined or winged. 



32. Verbesina. 

 Achenes very flat : bractlets of the receptacle flat or at least not clasping. 



Pappus of 2 short awns or teeth, or obsolete. 33. Coreopsis. 

 Pappus of 2-6 awns or teeth, upwardly or downwardly barbed. 



34. BiDENS. 

 Pappus of numerous scales. 



Heads with ray-flowers : leaves opposite ; blades toothed. 



35. Galinsoga. 

 Heads without ray-flowers : leaves alternate ; blades entire. 



36. Marshallia. 

 Tribe VI. HELENIEAE. 



A single genus in our range. 37. Helenium. 



Tribe VII. ANTHEMIDEAE. 

 a. Receptacle chaffy. 

 Involucre obovoid to campanulate : heads small : achenes flattened. 



38. Achille.\. 



