132 



DISPERSION OF POLLEN BY THE WIND. 



has remained rudimentary, project obliquely up into the air (see fig. 227). Tho 

 opening of the petals is immediately followed by the dehiscence of the anthers. 

 The coat of the anther shrivels up rapidly, leaving nothing but a little flap upon 

 which the pollen-cells rest. There are generally only 36 pollen-cells contained 

 in each anther. These are comparatively large and very sticky, they cohere 

 together and form a mass of pollen which is borne upon the thick stamen. 

 Notwithstanding the fact that they are very near the surface of the water, the 

 masses of pollen-ceUs are not easily wetted. The three sepals underneath them 

 form, as has been said, three boats which respond to the slightest movements 

 of the water without upsetting, and therefore protect their freight from wet to 



Fig. 227. 



Flowers of Vallisneria spiralis floatii]g on the surface of water. In the middle a female flower with several male flowers on 

 either side of it in various stages of development : some still closed, some in process of opening, some open with their 

 boat-shaped perianth-lobes thrown back. Projecting from the open flowers are the stamens. An open anther is attaching 

 its pollen to the fringed stigmatic margin of the female flower. xlO. 



perfection. These little floats are blown hither and thither by the wind and 

 accumulate in the neighbourhood of fixed bodies, especially in their recesses, 

 where they rest like ships in harbour. When the little craft happen to get 

 stranded in the recesses of a female Vallisneria flower they adhere to the tri-lobed 

 stigma, and some of the pollen-cells are sure to be left sticking to the fringes on the 

 margins of the stigmatic surfaces. 



Directly after the adhesion of the pollen, which takes place in the manner 

 shown in fig. 227, the female flower is drawn down under the water. The long 

 flower-stalk assumes a spiral form, and its coils close up so tightly together that 

 the ovary, or young fruit as it now is, is brought to rest at quite a small distance 

 above the muddy bottom of the water. 



Up to the present time the conveyance by the wind of adhesive pollen on 

 floats composed of the perianth of the flower is known to exist in the widely- 



