478 



COMPOSITAE (COMPOSITE FAMILY) 



Involucral bracts in more than two rows. 



Involucral bracts herbaceous or at least green-tipped. 

 Lobes or teeth of the leaves mucronate or bristle- 

 tipped. 



Involucral bracts in several series, usually recurved or 

 reflexed ........ 



Involucral bracts in 2-3 series, loose but not reflexed 

 Lobes or teeth of the leaves not mucronate or bristle- 

 tipped; involucral bracts often spreading, but not 

 recurved or reflexed. 

 Disk-flowers turning brown or reddish. 



Stems usually branching, and the heads several- 

 many 



Stems low, monocephalous; dwarf alpines. 



Stems scapose 



Stems leafy ....... 



Disk-flowers permanently white .... 



Bracts not foliaceous or noticeably green-tipped 

 Involucral bracts in 1 or 2 rows ..... 



Rays inconspicuous or wanting. 



Annuals, with numerous small heads and rays not longer 

 than the pappus ....... 



Perennials (shrubs); rays wanting 



23. Machaeranthera. 

 21. Xylorhiza. 



22. Aster. 



24. Oreastrum. 



25. lonactis. 



26. Leucelene. 

 28. Wyomingia. 



27. Erigeron. 



29. Leptilon. 



30. Baccharis. 



Tribe IV. INULEAE 



Receptacle chaffy; stigmas of hermaphrodite flowers not truncate . 31. Filago. 

 Receptacle not chaffy; stigmas of hermaphrodite flowers truncate. 

 Plants dioecious or polygamo-dioecious. 



Pappus of staminate flowers clavate .... 32. Antennaria. 



Pappus alike in all the flowers ...... 33. Anaphalis. 



Plants not dioecious; all the flowers fertile. 



All the flowers hermaphrodite ...... 34. Nacrea. 



Only the inner flowers hermaphrodite 35. Gnaphalium. 



Tribe V. HELIANTHEAE 



Involucral bracts not inclosing the ray achenes; herbage not glan- 

 dular viscid. 



Ray-flowers fertile and ligulate; disk-flowers sterile. 

 Ligules conspicuous . . 

 Ligules reduced to 2 or 3 teeth or wholly wanting. 



Caulescent annual ........ 



Acaulescent perennial . . . . 



Disk-flowers fertile; rays, if present, fertile or sterile. 

 Stamens distinct. 



Heads with both staminate and pistillate flowers. 



Involucral bracts acuminate ...... 



Involucral bracts obtuse. 



Fertile flowers more than one . 



Fertile flower solitary ....... 



Heads unisexual; pistillate heads usually spiny. 



Bracts of the staminate heads separate; pistillate head 

 forming an oblong bur ...... 



Bracts of the staminate heads united. 



Pistillate flowers solitary in each head; spines in a single 



series 



Pistillate flowers 1-4 in each head; spines in several 

 series ......... 



Stamens syngenesious. 



Ligules persistent and becoming papery. 



Achenes compressed; leaves entire .... 



Achenes 4-sided; leaves toothed 



36. Melampodium. 



37. Parthenice. 



38. Bolophyta. 



39. Oxytenia. 



40. Iva. 



41. Dicoria. 



44. Xanthium. 



42. Ambrosia. 



43. Franseria. 



Ligules deciduous or wanting. 



Receptacle high-conical or cylindrical. 



Rays pistillate, sterile. 



Ligules rose-colored 



Ligules yellow 



Rays neutral. 



Achenes 4-sided, marginless ..... 

 Achenes flattened laterally and margined 

 Receptacle flat to convex. 



Achenes not winged or very flat. 



Pappus wanting 



Pappus present (a laciniate crown or distinct scales). 

 Pappus coronifprm and persistent 

 Pappus of 2-pointed very deciduous scales 

 Achenes flat, winged or winglei 



ally 2-3-awned. 



(terete in No. 58), usu- 



45. Crassina. 



46. Heliopsis. 



47. Brauneria. 



48. Gymnolomia. 



49. Rudbeckia. 



50. Ratibida. 



51. Balsamorrhiza. 



52. Wyethia. 



53. Helianthus. 



