COMPOSITAE (COMPOSITE FAMILY) 481 



M- Pappus double. 



8. Chrysopsis. Heads many-flowered; rays numerous. The outer pappus of very small 



chaffy bristles, much shorter than the inner of copious capillary bristles. 



M- -M- Pappus simple. 

 a. Pappus a single row of capillary bristles. 



9. Chrysothamnus. Involucre narrowly turbinate; the bracts chartaceous, usually in 



5 vertical ranks. Rays none. Pappus a single row of capillary bristles. 



10. Isocoma. Involucre broadly turbinate; the bracts imbricated but not in vertical 



ranks. Rays none. Pappus as in the preceding. 



aa. Pappus of many unequal bristles. 



11. Sideranthus. Involucre hemispherical; the bracts chartaceous, with green tips. 



Rays usually present. Leaves with spinulose-tipped teeth. 



12. Pyrrocoma. Involucre hemispherical; the bracts more or less foliaceous. Rays 



conspicuous. Leaves with spinulose-tipped teeth, the basal large, the cauline 

 reduced. 



13. Oonopsis. Involucre from hemispherical to turbinate; the bracts more or less green- 



tipped and cuspidate-acuminate. Stems leafy up to the sessile heads. 



14. Macronema. Involucre turbinate; the outer bracts foliaceous. Rays often wanting. 



Stems leafy throughout. 



15. Stenotus. Involucre hemispherical; the bracts not green-tipped, mucronately acute. 



Rays few-several. Stems scapose or at least naked above. 



16. Tonestus. Involucre broadly hemispherical; the bracts herbaceous, very obtuse. 



Rays conspicuous. Stems low, equably leafy. 



17. Petradoria. Involucre turbinate to ovoid; the bracts in more or less distinct vertical 



rows. Achenes cylindric, 10-striate. 



18. Oreochrysum. Involucre campanulate; the bracts chartaceous or the outer foliaceous. 



Rays 1 2-20 . Achenes angled . 



aaa. Pappus of numerous capillary bristles. 



19. Solidago. Heads few-many-flowered, numerous, in racemes, panicles, or corymbs; 



rays 1-16. 



** Ray-flowers white, blue, pink, or purple, rarely yellow in no. 27. 

 *- Pappus very short, a mere crown or a few scales or awn-like bristles. 



20. Townsendia. Involucre broad, many-flowered; the bracts more or less scarious* 



margined. 



- -i- Pappus of numerous, long, and capillary bristles. 

 M- Rays conspicuous. 



21. Xylorhiza. Inyolucral bracts in about 2 series, mucronulate, carinate below, her- 



baceous with scarious margins. 



22. Aster. Involucral bracts in several series, usually herbaceous at tip, not reflexed or 



recurved. 



23. Machaeranthera. Involucral bracts herbaceous and spreading, or recurved or re- 



flexed, in several series. 



24. Oreastrum. Involucre hemispherical; the bracts narrow and subequal. Stems scapi- 



form, monocephalous. 



25. lonactis. Involucre hemispherical; the bracts imbricated, coriaceous, and wholly 



appressed. Stems equably leafy. 



26. Leucejene. Involucre turbinate; the bracts narrow, herbaceous but scarious-mar- 



gined. Leaves narrow, subulate, numerous, and mostly appressed. 



27. Erigeron. Heads many-flowered, on naked peduncles. Involucres of narrow equal 



bracts in two rows. Pappus simple or with some outer minute scales. 



28. Wyomingia. Heads large; the involucral bracts in 3-4 series, rigid with a thickened 



midrib. Pappus in 2 series, the outer short, multisquamellate. 

 ++ -H- Rays inconspicuous or none. 



29. Leptilon. Heads small, radiate or discoid; involucres campanulate; bracts narrow, 



in 2-3 series. Annuals. 



30. Baccharis. Heads rayless, many-flowered, dioecious (all pistillate or all staminate). 



Smooth glutinous shrubs. 



Tribe IV. INULEAE. Heads discoid (radiate only in Inula), the pistillate flowers mostly 

 filiform and truncate. Anthers sagittate, the basal lobes attenuate into tails. Style- 

 branches with unappendaged, obtuse or truncate naked tips. Pappus capillary or 

 none. 



* Receptacle chaffy. 



31. Filago. Receptacle hemispherical or conical; fertile flowers in 2 sets separated from 



each other by a ring of chaffy bracts. Low woolly annuals. 

 * * Receptacle naked; involucral bracts many, scarious; floccose-woolly herbs. 

 -)- Heads dioecious or nearly so. 



32. Antennaria. Heads dioecious. Pappus of sterile flowers club-shaped or barbellate; 



of the fertile capillary, united at base and deciduous together. 



33. Anaphalis. Heads dioecious or nearly so. Pappus not thickened above or at all 



united at base. 



+- *- Heads all fertile throughout. 



34. Nacrea. Flowers all hermaphrodite; pappus clavate-thickened upward. 



35. Gnaphalium. Flowers all fertile but only the inner hermaphrodite; pappus cap- 



illary. 



Tribe V. HELIANTHEAE. Heads radiate or discoid; involucre not scarious (nut-like 

 in fruit in nos. 42, 43 and 44). Receptacle chaffy. Pappus never capillary, sometimes 

 none. Anthers not caudate. Style-branches truncate or hairy-appendaged. 

 * Ray-flowers fertile and ligulate (sometimes obsciirely so); disk-flowers sterile, 

 -i- Ray flowers with conspicuous ligules. 



36. Melampodium. Involucral bracts in 2 very dissimilar sets. 



ROCKY MT. EOT. 31 



