876 MISC. PUBLICATION 42 3, U. S. DEPT. OF AGRICULTURE 



10. Phyllaries scarious; corollas rarely purplish; plants tomentose (11). 

 11. Heads subdioecious, the pistillate ones usually with a few central 



hermaphrodite flowers 36. Anaphalis. 



11. Heads all alike and heterogamous 37. Gnaphalitjm. 



5. Phyllaries herbaceous, at least in the center (12). 



12. Heads unisexual; plants dioecious 30. Baccharis. 



12. Heads not unisexual (13). 



13. Plants low, depressed, scurfy-pubescent, winter-annual; leaf blades 



broadly ovate or suborbicular 113. Psathyrotes. 



13. Plants perennial or, if annual, then not low and scurfy-pubescent (14). 



14. Phyllaries and leaves bearing conspicuous translucent oil glands (15) . 



15. Phyllaries relatively numerous, usually in more than 1 series and 



with some bractlets at base; pappus bristles basally united in 



groups 103. Dyssodia. 



15. Phyllaries few (5 to 8), free, equal, strictly 1-seriate; pappus 



bristles free, numerous 104. Porophyllum. 



14. Phyllaries and leaves sometimes impressed-glandular but not with 

 translucent oil glands (16). 



1 6. Phyllaries proper 4 to 7, in a single series, of equal length (17) . 

 17. Plant herbaceous; leaves very large, decompound. 



114. Cacalia. 



17. Plant shrubby; leaves narrow, entire 115. Tetradymia. 



16. Phyllaries more than 7 (18). 



18. Pappus bristles plumose (19). 



19. Annual herb, with deltoid-ovate leaves and cylindric heads, 

 these in a slender leafless virgate panicle. 



3. Carminatia. 



19. Perennial herbs or shrubs; leaves and inflorescence 



otherwise (20). 



20. Intricately branched shrub; corollas yellow. _ 77. Bebbia. 



20. Perennial herbs, or shrubby at base, not much branched; 



corollas whitish (21). 



21. Leaves lanceolate or ovate, 3-nerved; heads 9- to 12- 



flowered 6. Brickellia. 



21. Leaves narrowly linear or linear-lanceolate, 1-nerved; 



heads many- flowered 7. Kuhnia. 



18. Pappus bristles not plumose (22). 



22. Plants shrubby; leaves of the branches reduced to scales; 

 involucre strongly graduated, the phyllaries not in vertical 

 ranks (23). 

 23. Phyllaries lanceolate, acute; achenes silky-pubescent. 



27. Aster. 



23. Phyllaries ovate to oblong, obtuse; achenes glabrous. 



110a. Lepidospartum. 

 22. Plants otherwise in habit and foliage, or else the phyllaries 

 in distinct vertical ranks (24). 



24. Shrub; leaves crowded, linear-filiform, subterete, im- 



pressed-punctate; involucral bracts nearly in 1 series 

 and of equal length, subulate, herbaceous. 



112. Peucephyllum. 



24. Herbs or, if -shrubby and with subterete impressed-punctate 



leaves, then the involucral bracts not equal, nor subulate, 



nor herbaceous (25). 



25. Pappus double, the outer series of short scales, the inner 



series of capillary bristles; white-barked shrub with 



small leaves, the petioles much longer than the blades. 



2. HOFMEISTERIA. 



25. Pappus simple or else the plants herbaceous (26) . 



26. Heads with the outer flowers pistillate and the central 

 flowers hermaphrodite (27). 

 27. Phyllaries subequal; corollas whitish.. 29. Conyza. 



27. Phyllaries distinctly graduated; corollas purplish. 



31. Pluchea. 

 26. Heads with all of the flowers hermaphrodite (28). 



28. Pappus of 2 to 8 caducous bristlelike awns; herbs, 



more or less viscid 10. Grindelia. 



