DEVELOPMENT OF PLANTS 



457 



golden-rod (Solidago), aster, fleabane (Erigeron), cat's-paw 

 (Antcnnaria), everlasting (Gnaphalium), rosinweed and com- 

 pass plant (SUphium), Spanish needles (Bidens), daisy (Chrys- 

 anthemum), groundsel (Scnecio), thistle (Carduus). Culti- 



Fig. 341. Flowers and fruit of Bidens: A, sectional view of the inflor- 

 escence — r, ray flowers ; d, disc flowers ; in, bracts of the involucre. B, 

 disc flower before opening, the shaded region showing the position of the 

 anthers in the corolla — c, calyx or pappus in the form of downwardly 

 barbed bristles ; b, bract or chaff associated with the disc flowers. C, early 

 stage in the opening of the flower. The stamens have been lifted beyond 

 the mouth of the opened corolla by the growth of their filaments and the 

 style is elongating, pushing out the spores, which appear in little piles at 

 the top of the anthers. D, last stage in the bloom of the flowers. The 

 style has grown beyond the anthers and the stigmatic lobes have reflexed, 

 touching the spore-covered style. E, a sterile ray flower, much less en- 

 larged. F, the fruit, showing the barbed pappus for dissemination. 



