382 COLLEGE BOTANY 



small, perfect, polygamous, monoecious or dioecious; the mar- 

 ginal flowers when present are known as the ray flowers and have 

 strap-shaped corollas, the central or disc flowers may be of this 

 same type or may he tubular; the calyx is rudimentary (sun- 

 flower) or hairy (dandelion) and adheres to the ovary; the 



FIG. 224. Sunflower head. Composite type of inflorescence. 



corolla is five-parted and gamopetalous ; stamens five, attached 

 to the corolla, anthers united into a tube around the style ; style 

 two-cleft; fruit a one-seeded achene (Figs. 223, 224). 



This family includes many ornamental plants, such as chrys- 

 anthemums, asters, daisies, sunflowers (Fig. 136), etc., and 

 many weeds, such as ironweed, goldenrods, fleabane, rosin- 

 weeds, ragweeds, burdock, thistle, dandelion, etc. 



