ANIMALS AND PLANTS 253 



ing the germination. The mountain laurel (Kalmia) 

 of eastern America has the stamens in the freshly 

 opened flower bent outward, and the anther fitted into 

 a little pocket from which it is set free by an insect visit- 

 ing the flower ; the suddenly released stamens spring 

 inward much as in the barberry and scatter their pollen 

 in the same way. 



Among the sympetalous Dicotyledons the devices for 

 effecting cross-pollination are often exceedingly perfect. 

 Most of these have tubular and often two-lipped flowers 

 which are very generall} r incapable of self-fertilization. 

 The labiate flowers are usually horizontal or pendulous, 

 and often adapted to special insects. Thus the common 

 foxglove (Digitalis) is mainly visited by large bees, 

 which creep into the bell-shaped corolla, where the back 

 comes in contact with the open anthers which lie against 

 the upper part of the corolla. Here the stamens mature 

 first, so that ordinarily the pistil is pollinated by pollen 

 from a younger flower, but it is said that in case insects 

 are prevented from visiting the flower, self-fertilization 

 is possible. 



In various Labiatre, or Mints, e.g. Lamium, Sal via 

 (Fig. 57, A, B), the arrangements for cross-fertilization 

 are very complete, and probably in both of these genera 

 self-fertilization is impossible. In the former, while 

 stamens and pistil mature about the same time, the 

 stigma hangs below the stamens, and its receptive sur- 

 face is turned away from them so that no pollen can 

 fall on it from above, and a bee entering the flower, 

 with pollen taken from another one, will touch the 

 stigma and deposit the pollen upon it, before it comes 

 in contact with the stamens. In the various species 



