THE HIGHER DICOTYLEDONS. 



353 



part, the whole forming a delicate lever. A bee on entering 

 the flower (Fig. 144) pushes against the united lower ends of 

 the two connectives, in poking for the honey, and causes the 

 curved connectives to swing on the filaments as on hinges, 

 so that the two fertile anther-lobes (a) come down and strike 

 the bee's back, dusting it with pollen. As the bee retires, the 

 stamens return to their former place under the corolla-hood. 



III. 



Fig. 144. 



I., Flower of Sage from side ; II., With Humble-bee extracting Nectar, and the 

 Anthers rubbing against his back ; III., Single Stamen. 



In an older flower the style bends down and the stigma is 

 touched first by a bee entering the flower. 



[The long-tubed red flowers of Monarda are largely visited 

 by butterflies, and some tropical species of Salvia are 

 pollinated by humming-birds.] 



Cross-pollination is promoted by the occurrence, often on 

 different plants, of pistillate flowers besides the ordinary 

 flowers, as in Thyme, G-round Ivy, Corn Mint, Self-heal. 



358. Foxglove (Digitalis purpurea), the most familiar 

 and most conspicuous British plant of this family, is 

 abundant in sandy or rocky soils in open places or the edges 

 and less shaded parts of woods. It is usually biennial, 

 forming in its first year a rosette or broad- stalked " radical " 

 leaves with prominent veins and wrinkled surface, 6 to 

 12 ins. long ; in the second year the stem grows up to form a 

 flowering shoot, 1 to 5 ft. high, with spaced-out leaves 

 gradually becoming smaller and sessile. In sheltered places 

 especially the plant becomes perennial, as do also the garden 

 varieties. 



23 



I. 13. 



