SEPTEMBEll 



21 



somewhat shaded are always paler than those which re- 

 ceive the full warmth of the sun. 



The calyx is pale green and fine toothed ; the corolla, 

 large, funnel form, and with a five-toothed plaited border ; 

 the pistil has a two-lipped stigma; stamens, five. The 

 odor of the flowers attracts numerous insects who, in 

 entering the corolla for the honey, become dusted with 



Cross-section of flower of the Jamestown Weed. Ripe pod. 



the very abundant pale yellow pollen (flower dust), and 

 then carry this pollen from flower to flower, in going 

 from one to another in search of more food. This is 

 most advantageous for the plant, because, as Darwin has 

 shown, the seeds which result from cross-fertilization, 

 accomplished by the action of the pollen of one flower 

 on the ovules in the seed box at the base of the pistil of 

 another, are usually heavier and more numerous than 



