No. 439-] XORTI/ERX OA M OP FTM.OFS FLOWERS. 



as Chrysopsis, or golden aster. Solidago (with one exception), 

 and Senecio. The capitula are both discoid and radiate, and as 

 a rule both ray and disk Mowers are yellow. Hut the disk 

 Mowers in some genera have become blown or purple. In Rud- 



in Hehanthus six species have the disk purple or brown, and in 

 sixteen species the disk is yellow; and in Coreopsis both rays 

 and disk vary from vellow to brown. 



One hundred and twenty-six species have white flowers. In 

 many instances where the ray flowers are white the disk flowers 

 are yellow. In these bicolored capitula there can be little doubt 

 that the white rays are derived from yellow-flowered progenitors. 

 In Verbesina (crownsbeard) all of the five species have yellow 

 disks, but one has white and four yellow rays. The white dis- 

 coid heads seem also to have been originally yellow. Of the 

 discoid heads of 1 1\ menoppapus two species are yellow and 

 three are white. A number of genera, as Antennaria. Filago 

 and Gnaphalium, consist of white woolly herbs with yellowish 

 white often inconspicuous flowers, which have undergone much 

 retrogression. The white-flowered species appear to be of later 

 origin than the yellow, and in numerous instances to be derived 

 from them. 



There are only four red to sixty-four purple, and fifty-nine blue 

 flowers. The heads are both discoid and radiate. While the 

 rays may change directly from yellow to red. purple, or blue, in 

 many instances they have probably passed through an interme- 

 diate white stage. In Boltonia, which has the disk yellow, one 

 species has the rays white, and in two others they are blue or 

 violet. In Aster the rays are white in twenty-two species, purple 

 in six, and blue in forty-four. In Erigeron the white rayed 

 species frequently vary to pink or purple. In Coreopsis twelve 

 species have the rays yellow like the disk, but in one they are 

 pink, and in the variety Golden Wave they often change from 

 golden yellow to maroon. In some species of Aster the disk 

 flowers change from yellow to red or blue, as in A. rose i Jus. A. 

 carmesinus, and in A. curve scens. Whether the purple discoid 



