KEY 



PLANTS HAVING MINUTE FLOWERS CROWDED IN 

 HEADS, WITH OR WITHOUT RAY FLOWERS. 



Plants having no ray flowers. 



LEAVES OPPOSITE. 



(at least the lower, or in clusters around the stem.) 



1. flower-heads whitish or magenta-crimson. 



Eupatorium. 



2. flower-heads about one inch broad, yellow. Bidens. 



3. flower-heads purple, foliage fragrant. Pluchea. 



LEAVES ALTERNATE (at least the majority). 



1. alternate and basal; flower-heads whitish. 



Sericocarpus. 



2. flower-heads purple. Liatris. 



3. flower-heads short, slender, yellow or whitish. 



Solidago. 



4. flower-heads green-white. Erigeron (canadensis) . 



5. stem and leaves having long, white wool; flower- 



heads whitish. Anaphalis. 



6. more succulent plant than preceding. Gnaphalium. 



7. flower-heads green. Ambrosia. 



8. leaves finely-divided, fragrant; flower-heads oys- 



ter-white or pink. Achillea. 



9. foliage fragrant; flower-heads button-like, yellow. 



Tanacetum. 



10. leaves finely cut and covered with white wool; 



flowers greenish-yellow or yellow-white. 



Artemisia. 



11. plants having abundant juice, rank odour; flower- 



heads white. Erechtites. 



12. leaves spiny; flower-heads magenta or yellow. 



Cirsium. 



Plants having ray flowers. 

 LEAVES BASAL 



1. flower-stem thickened below the flower-heads; 

 flower-heads yellow. Leontodon. 



xx 



