352 



HUTCHINSON'S POPULAR BOTANY 



FIG. 433. ANNUAL CHRYSANTHEMUM (Chrysanthemum carinatum). 



Section througn a flower-head (capitulum) to show how tlie numerous florets are arranged upon the receptacle. 



head having been cut through longitudinally in order to exhibit a perfect 

 row of the disc florets. Each of these florets, which you will observe are 

 tubular in form, is a perfect flower, capable of setting seed. The corolla- 

 tube covers at its base the ovary, and hides from view the greater part 

 of the styles, the only portion visible being the end which bears the 

 branched stigmas. Surrounding the flower-head are some florets of another 

 kind, each of the so-called petals being a female flower, or, in scientific 

 parlance, a rayed floret with ligulate (i.e. strap-shaped) corolla. 



One of the great purposes effected by the massing together of the florets 

 in composite flowers is admirably suggested by Kerner in his remarks upon 

 the taking up of pollen by insects. " Great quantities of pollen," he tells us, 

 " adhere to the under parts of insects in the case of composite inflorescences. 

 Shortly after the opening of the corollas the style bearing an external load 

 of pollen is exserted from each of the little tubular and ligulate florets 

 composing the capitulum in this group, and, owing to the fact that large 

 numbers of these florets invariably open simultaneously, numbers of styles 

 laden with pollen project close together from the discoid head. A largish insect 

 settling on a capitulum may therefore be dusted with the pollen of numerous 

 florets at once." Darwin observes that the ray-florets of composite flowers 

 protect the florets of the disc by folding inwards at night and during rainy 



