CH. xvi POLLINATION AND FERTILISATION 207 



Pollination. Pollination may take place in two different 

 ways. 



(1) Cross- Pollination. When the pollen of a flower is dis- 

 tributed to the pistil of another flower it is said to be cross- 

 pollinated. 



(2) Self-Pollination. When the pollen of a flower is dis- 

 tributed to the pistil of the same flower it is said to be self- 

 pollinated. 



Cross-Pollination. It has been proved with many plants 

 that cross-pollination produces a better crop of seeds ; and that 

 the plants produced from these seeds are stronger and better 

 able to survive in the struggle for existence. It was pointed 

 out by the late Charles Darwin * that cross-pollinated flowers 

 produce offspring which possess (a) greater strength ; (b} the 

 habit of earlier flowering ; (c) greater diversity of colour, than 

 the self-pollinated flowers. Cross-pollination can take place in 

 two ways : 



(1) By the pollen being carried from the anther of one flower 

 to the pistil of another flower by insects. Those plants which 

 possess flowers which are pollinated by insects are called 

 cntomophilous or " insect-loving " plants. 



(2) By the pollen being carried from the anther of one flower 

 to the pistil of another flower by the ivind. Those plants 

 which possess flowers which are pollinated by the wind are 

 called anemophilous, or " wind-loving " plants. 



Why Insects visit Flowers. Insects are attracted to 

 flowers by their shape, colour, and perfume. Many flowers also 

 produce honey which the insects use for food. Organs which 

 produce honey are called nectaries or honey-glands (p. 195). 

 These nectaries occupy different positions in different plants. 

 Thus, in the flowers of the Wallflower there are two nectaries, 

 which occur at the base of the short stamens, and the sugar 

 solution or honey which they produce is stored up in the 

 saccated lateral sepals. In the Christmas Rose, the modified 

 petals, which are tubular in shape, bear nectaries. The nectary 

 in the spotted orchid is in the twisted spur, and it is necessary 

 for the bee to put its tongue or proboscis down this spur in order 



1 The Cross and Self -Fertilisation in Plants. 



