COMPOSITAE — THISTLE FAMILY 757 



The Compositae are divided into two sub-families : the Tubuliflorae with 

 corolla tubular in all the perfect flowers, S-lobed, rarely 3-4-lobed, ligulate only 

 in the marginal flowers, called the ray flowers, which are absent in some species; 

 the Liguliflorae with corolla ligulate in all the flowers of the head and all the 

 flowers perfect; herbs with milky juices and alternate leaves: The former con- 

 tains the tribes Vernonieae, with the large genus Vernonia of 450 species mostly 

 of the tropics; the Eupatorieae, containing Enpatorium; Astereae, containing 

 Solidago, Aster, Erigcron, Grindclia, Bigelovia; Iniileae, containing Inula, An- 

 tennaria; Heliantheae, containing Silphium, Parthenium, Helianthiis, Bidens, 

 Coreopsis): the Helenieae with Hclenium, Actinella; the Anthemideae with 

 Anthemis, Achillea, Tanacetum; thQ Senectoneae with Senecio, Tussilago; the 

 Cynareae with Arctium, Cnictts, Cirsiuin and Centaurea. The Liguliflorae con- 

 tain but one tribe, the Cichorieae, which contains the genera Taraxacum, dehor- 

 turn, Lactuca, Hieracium, Sonchus and Scorzonera. 



Genera of Compositae , 

 Corolla ligulate in all of the flowers of the head; flowers perfect. 



Liguliflorae Cichorieae 



Pappus none 1. Cichorium 



Pappus composed of capillary bristles. 



Flowers yellow, achenes not beaked 2. Sonchus 



Flowers yellow, purplish or cream colored. 



Achenes beaked 3. Lactuca 



Achenes not beaked 4. Lygodesmia 



Corolla tubular in perfect flowers, 5 or rarely 3 or 4-lobcd ; lingulate only in 



the marginal flowers. TUBULIFLORAE 



Stamens distinct or nearly so. Ambrosieae. 



Staminate and pistillate flowers in the same head 5. Iva 



Staminate and pistillate flowers in a separate head. 



Involucre of pistillate heads with several tubercles 6. Ambrosia 



Involucral bracts of pistillate flowers forming a bur 7. Xanthium. 



Stamens generally united by their anthers into a tube around the style. 

 Anthers not tailed. 



Style branches thickened upward, papillose. EupatoriEae. 



Achenes 3-5 angled, flowers discoid 8. Eupatorium 



Achenes 8-10, ribbed or striate. 



Bracts of involucre in several series 9. Liatris 



Bracts of involucre in 2 or 3 series 10. Trilisa 



Style branches of perfect flowers flattened with terminal ap- 

 pendages. Astereae. 

 Ray flowers yellow. 



Pappus of scales or awns 11. Grindelia 



Pappus of numerous capillary bristles 12. Solidago 



Ray flowers not yellow, bracts nearly equal 14. Erigeron 



Bracts in several unequal series 13. Aster 



Style branches truncate or hairy appendaged. Heliantheae. 



Pappus wanting or minute crown 15. Rudbeckia 



Pappus of 2 persistent downwardly barbed awns or tubes 



16. Bidens 



