DICOTYLEDONS. 



235 



hairs, or rarely wanting ; corolla tubular, 5-toothed or rarely 

 bilabiate, the corollas of the marginal flowers often prolonged 

 into a strap-sha23ed or ligulate ray ; when both tubular and 

 ray flowers are present the head is said to be radiate, and 

 when all the flowers are tubular it is said to be discoid ; sta- 

 mens usually 5, united by their anthers into a ring about 

 the slender, 2-cleft style ; fruit an achene. 



The largest family of flowering plants, and the one in 

 which the flowers are most highly specialized. Fully ten 

 thousand species are known, though comparatively few are 

 of great economic importance. ^lost of the species bloom 

 late in the season. 



Heads discoid. 



Receptacle naked. 



Pappus of chaffy bristles 



Pappus of capillary bristles . 



Pappus of plumose bristles . 



Pappus of bearded bristles . 

 Receptacle chaffy 

 Receptacle bristly . 



Heads radiate. 

 Rays yellow. 

 Receptacle naked. 

 Pappus capillary, heads racemed . 

 Pappus capillary, heads corymbed 

 Pappus of chaffy scales 



Receptacle cliaffy. 



Leaves alternate, rays fertile 

 Leaves alternate, rays neutral 



Leaves opposite. 



Pappus of 2 chaffy scales or wanting. 



Involucre in several rows 



Involucre in 2 rows 

 Pappus of 2-4 barbed awns 



I. Elephantopus. 

 II. Eupatoriuni. 



III. Lacinaria. 



IV. Trilisa. 

 XII. Bidens. 



XVI. Carduus. 



V. Solidago. 

 XV. Senecio. 

 XIII. Ileleniuni. 



\'III. Silphiuni. 

 IX. Rudk'ckia. 



X. Ilclianthus. 

 XT. ('oreoi)sis. 

 XII. Bidens. 



