Journal of Agriculture , Victoria. 



[lo Jan., 1911. 



The pistil is generally in the centre, and it may either be whole in 

 formation, as in the lily ; or it may be subdivided into various sections, 

 according to the variety of species — in pear flowers, the pistil is divided 

 into five divisions. The tip of the pistil is generally enlarged, or ex- 

 panded, and this portion is known as the stigma. The stigma is the 

 first reproductive organ to be developed. While the stigma is often fully 

 developed before the flower opens, the anthers open at various times ; 

 and it may generally be noticed that both opened i,nd unopened anthers 

 are existent on the flower at the same time. Thus, a constant supplv 

 of pollen is available for the flower, or for other flowers. 



Pollination and Fertilization. 



The office of the stigma is to receive, on its surface, the pollen grains 

 from the anthers ; and it is ripe for this purpose, either when the surface 



IS clearly rough or hairy, or when it i.s moist 

 or glutinous. These conditions vary in dif- 

 ferent species of flowers. When the pollen 

 is received on the stigma, the act is known as 

 pollination. The pollen there germinates or 

 sends a very fine tube through the pistil into 

 the centre of the young or embryo fruit, where 

 the young seeds or ovules are placed. The 

 pollen tube there impregnates or fertilizes the 

 ovules, and these ultimately become ripened 

 into seeds. This action is known as fertiliza- 

 tion. Thus, pollination may take place, but 

 unless fertilization results, the action is 

 useless. 



Pollination may take place by the pollen 

 naturallv falling on the stigma ; it may be 

 blowai there by the wind ; or it may be carried 

 from flower to flower, by the agency of bees, 

 moths, and other insects. If fertilization 

 does not occur after the lapse of its natural 

 FLOWER OF cisTUs; SEPALS time, the whole flower simply drops off the 

 and petals removed. tree. 



The stamens have their anthers in LIMITATIONS, 



contact with the stigma. The pollen r • 1 1 1 r 



tubes are shown passing? down the it IS thuS shOWn that, DCtOre a 



style and enterinff the ovules. ^^^^ ^^^^ " Set " " itS fruit, the actof 



fertilization must inevitably happen ; either a flower must be fertilized 

 by its own pollen, which act is called self-fertilization, or it may be 

 fertilized from the flowers of another tree, in which case the operation is 

 termed cross-fertilization. There are limitations to this action, and to 

 results ; and they must be taken into account when considering the 

 question. It is undoubted that when cross-fertilization occurs, much finer 

 and better fruits result, than when self-fertilization occurs. W'aite 

 found, in his experiments, that in self-pollinated fruits, the tendency of 

 the fruit was always to be smaller, while the largest fruits were alwavs 

 the result of crosses. Thus, to carry pollination and fertilization to a 

 thoroughly successful issue, it is necessary to "cross" the stigmas with 

 pollen from other varieties. There is a limitation here, owing to the 

 variability in the times of flowering ; and the choice of the operator, for 

 commercial fruit production at any rate, is limited to crosses between 



