1907] Hall. Compositae of Southern California. 15 



Achenes 5-angled or -ribbed. 



Pappus-bristles 10 to 12 1. HOFMEISTERIA, p. 27. 



Pappus-bristles only 3 2. MALPEBIA, p. 28. 



Achenes 10-nerved 3. BEICKELLIA, p. 28. 



t 



TRIBE 2. ASTEREAE. ASTER TRIBE. 



Ours all herbs or shrubs with alternate leaves and scentless 

 herbage (but sometimes resinous or gummy). Bracts of the in- 

 volucre commonly well imbricated (nearly equal in Erigeron and 

 Conyza). Keceptacle naked in our genera. Disk-flowers mostly 

 yellow, perfect in all ours save Baccharis. Eays present or ab- 

 sent. Anthers obtuse at base. Style-branches of perfect flowers 

 flattened, conspicuously margined by the stigmatic lines, tipped 

 with a hispid or papillose appendage (this sometimes quite ob- 

 solete). Pappus mostly of awns or bristles (truly paleaceous 

 among our genera only in Gutierrezia and Amphiachyris). 

 A. Rays present, yellow. (B on p. 16.) 



Pappus of several short scales: heads very small: perennials 



4. GUTIEBEEZIA, p. 34. 



Pappus of 2 to 8 caducous bristles or awns: heads large: perennial herbs 



6. GBINDELIA, p. 37. 



Pappus of persistent bristles or awns. 



Stems herbaceous throughout (annual and perennial herbs). 



Eay-achenes without pappus 9. HETEEOTHECA, p. 41. 



Bay-achenes wdth pappus. 



Pappus-bristles 3 to 8 : annual 7. PENTACHAETA, p. 39. 



Pappus-bristles more numerous (perennials, except 2 species of 

 no. 13). 



Herbage villous or hirsute: pappus-bristles, equal or with a 



very short outer series 10. CHEYSOPSIS, p. 43. 



Herbage never villous or hirsute (glabrous to canescent or 



tomentose). 

 Bristles of the pappus equal (involucre 4 to 6 mm. high; 



bracts obtuse or merely acute) 11. SOLIDAGO, p. 45. 



Bristles of the pappus unequal (involucre 6 to 12 mm. high; 



bracts acuminate to subulate or spinose-tipped) 



13. HAPLOPAPPUS, p. 49. 



Stems suffrutescent, at least below (perennial shrubs). 



Heads solitary, terminating nearly naked peduncles: pappus perma- 

 nently clear white. 



Involucral bracts acute: pappus-bristles all slender 



12. STENOTUS, p. 48. 



