874 MISC. PUBLICATION 423, U. S. DEPT. OF AGRICULTURE 



13. Pappus otherwise (14). 



14. Leaves and involucre conspicuously punctate with translucent 

 oil glands (15). 

 15. Pappus of 3 to 6 entire paleae; phyllaries strictly 1-seriate, 

 united essentially to the apex into a toothed cup or tube. 



102. Tagetes. 



15. Pappus of paleae dissected into bristles, or else of 10 paleae 



or squamellae; phyllaries more or less distinctly 2-seriate. 



103. Dyssodia. 

 14. Leaves and involucre sometimes impressed-punctate, but not 

 with translucent oil glands (16). 



16. Pappus of 12 or more paleae, these nearly or quite as long as 



the achene (17). 

 17. Herbs; involucre not conspicuously graduated. 



91. Hymenothrix. 

 17. Shrubs; involucre conspicuously graduated (18). 

 18. Leaves opposite; corollas purple-tinged. 



5. Carphochaete. 

 18. Leaves alternate; corollas yellow (19). 



19. Plant very viscid; paleae of the pappus 12 to 16, 



essentially equal 11. Vancleve a. 



19. Plant not viscid; paleae and bristles of the pappus 

 more numerous, distinctly graduated. 



14. Acamptopapptjs. 



16. Pappus of fewer than 12 paleae or squamellae. or else these 



much shorter than the achene (20). 



20. Heads 5-flowered; pappus of 3 to 5 awns, with or without 



as many short squamellae, or reduced to a toothed crown. 



1. Stevia. 



20. Heads with more numerous flowers, or else the pappus 



otherwise (21). 



21. Achenes strongly compressed; pappus of 1 or 2 slender 



awns and often a crown of squamellae, or of a crown 



of lacerate squamellae only (22). 



22. Achenes not evidently ciliate; pappus of 1 or 2 awns. 



84. Laphamia. 

 22. Achenes strongly ciliate on the margin; pappus of a 

 crown of squamellae and often 1 or 2 awns (23) . 

 23. Heads radiate; leaves not hastate- triangular or 



caudate-acuminate 83. Perityle. 



23. Heads discoid; leaves hastate-triangular, caudate- 

 acuminate 85. Pericome. 



21. Achenes not compressed, or else the pappus otherwise 

 (24). 

 24. Pappus a low entire crown; low annual herb, pine- 

 apple-scented 108. Matricaria. 



24. Pappus otherwise; plants not pineapple-scented (25). 

 25. Heads mostly 4- to 6-flowered, about 2.5 cm. high. 



5. Carphochaete. 

 25. Heads with more numerous flowers, or else much 

 smaller (26). 

 26. Pappus a crown of short dissected squamellae, or 

 of 5 paleae dissected into bristles (27). 

 27. Glabrous annual; phyllaries chartaceous, green- 

 tipped; pappus a low dissected crown. 



22. Greenella. 



27. Woolly annual; phyllaries not chartaceous; 



pappus of 5 paleae dissected into numerous 



bristles 97. Trichoptilium. 



26. Pappus otherwise (28) . 



28. Phyllaries with a thin, scarious, white, yellow, 



or purplish margin and tip (29) . 

 29. Plants tomentose; pappus of 10 or more 

 paleae or squamellae. 



90. Hymenopappus. 



