Reconquest of the Water 
From the very moment when these tiny infant lobes 
emerge from the protecting mother-sheath, the gentle 
pulling and swaying of the current is acting upon them 
and they yield to it; indeed, they are always swaying 
to and fro in the water, and in rivers seem never to 
rest at all. 
According to one authority, it is sometimes possible 
to produce the air-type of leaf under water by using 
certain salts, which probably check the ordinary expan- 
sion of submerged leaves.5 
The real difficulty of water plants arises when flowers 
have to be produced. In almost all cases the flowering 
branches rise up above the surface, so that the stamens 
and pistils are exposed to insects or the winds. But 
the long-stalked water-lilies simply allow their flowers 
to float upon the surface, where they are abundantly 
visited by bees and crowds of other insects. The 
beautiful arrangements of Vallisneria have been so often 
explained that we prefer to describe the Canadian weed 
(Elodea), which is not so well known. The female 
flower has a very long flower-tube (about 4 to 8 inches), 
which grows rapidly, and finally opens on the surface 
of the water. It is beautifully buoyed up by three 
rows of air-spaces, and so shaped that water cannot get 
into the long funnel-shaped interior. The male flowers 
break off and float up to the surface, where the stamens 
open and set free the pollen. 
The little grains of pollen are covered with minute 
spines, Because of these little projecting teeth, an air 
film surrounds the pollen grain, so that it floats 
(although itself heavier than water) and drifts about on 
the surface. Should they by chance reach a female 
flower, they are drawn by capillary attraction into its 
funnel and so touch a stigma and effect fertilisation.‘ 
The point of this story lies in the fact that many pollen 
128 
