266 



BOTANY. 



scented as well as showy, their regularity of form prevents 

 perfect cross-pollination. However, as the flowers are 

 generally in clusters, it usually happens that the pollen 

 from one flower is carried to the stigmas of another. The 

 attractiveness of the flowers is such that through the visits 

 of great numhers of insects the large amount of pollen is 

 pretty well distrihuted upon other stigmas. 



539. In the nearly related Leguminous Plants, as beans, 

 peas, clover, lupines, etc., the perianth is not regular. 

 There are three forms of petals in each flower, viz., one 



Fia. 145.— Flower o£ Dead-nettle, side view and vertical section. Magnified. 



large broad one, the "banner," two lateral ones, the 

 "wings," and two anterior ones which together form the 

 "keel." These all together form a structure enclosing the 

 stamens and pistil in such a way that an insect cannot get 

 any of the nectar at the base of the corolla without setting 

 free some of the pollen, which adheres to the hairs of its 

 body and is thus carried to the stigma of some other flower. 

 540. In the Gamopetalse the union of petals into a tube 

 serves to compel insects to visit the flower in one way only. 

 In the Mints (Fig. 145) the flower is two-lipped, the broader 



