98 THE VICTORIAN NATURALIST. 



ON THE FERTILIZATION OF PHANEROGAMS. 

 I. — Dispersion of Pollen by the Wind. 

 By G. Weindorfer. 

 {Read he/ore the Field Naturalists^ Cluh of Victoria, I3th October, 1902.) 

 For the conveyance of pollen between flowers there exist two 

 main agents, viz., the wind and insects. Phanerogamous plants 

 have been separated by botanists into " anemophilse," or wind- 

 fertilized, and " entomophilae," or insect-fertilized plants. 



As would be naturally expected, it is, speaking generally, only 

 pollen of a dusty consistency which is transported by the wind ; 

 but the pollen of some flowers is occasionally torn away from the 

 anthers, in the form of sticky masses, and conveyed to the stigmas 

 oi neighbouring flowers by the wind, but the occurrence can only 

 be looked upon as accidental, and would happen only in the 

 rarest instances. 



Still more remarkable is the fact that in certain water plants the 

 pollen, though cohering in sticky masses, is blown by the wind in 

 a kind of little boat to the stigmas, which are raised above the 

 surface of the water. The phenomenon was first observed on 

 Vallisneria spiralis, a water plant, widely distributed in Southern 

 Europe and also in Australia. Here we have a plant, living 

 under water, whose leaves, arising from the stems, are erect, very 

 long, and like thin ribbons. In the axils of these leaves a variety 

 of buds are produced, of which generally two grow straight up- 

 ward. Each of the upward growing shoots prod ices a kind of 

 bladder in which are the flower buds. These, hitherto connected 

 with the axis of the raceme by diminutive stalks, become detached, 

 ascend in the water, and float about on the surface. Three con- 

 cave leaflets (the sepals), which form the outer whorl of the 

 perianth, are thrown back, and assume the appearance of three 

 boats connected together at one spot, and the stamens project 

 obliquely up into the air. The opening of the petals is immedi- 

 ately followed by the dehiscence of the anthers, which contain 

 generally only thirty to forty comparatively large and very sticky 

 pollen cells. The three sepals underneath the anthers respond to 

 the slightest movements of the water without upsetting, and are 

 blown to and fro by the wind, and accumulate in the neighbour- 

 hood of fixed bodies. When the little craft happen to get 

 stranded in the recesses of a female Vallisneria flower they adhere 

 to the three-lobed stigma, and some of the pollen cells are sure to 

 be left sticking to the fringes of the margin of the stigmatic sur- 

 faces. This kind of fertilization through the wind is known in 

 only thirteen species of the Hydrocharideas. 



The number of plants which produce pollen in form of a fine 

 dust, and wherein the pollen is dispersed exclusively and through- 

 out the period of flowering by the winds, would probably exceed 

 10,000 — about a tenth of the total number of Phanerogams. One 



