92 



PRINCIPLES OF PLANT CULTURE 



another more delicate scale, palea, together with the 

 stamens and pistils (Figs. 53-55). 



149. Fecundation is the union of the male and female 

 cell by which the new plantlet is formed. The term 

 fertilization that has been commonly used for this process 

 tends to confusion, because this term is also applied to 

 the addition of plant-food to the soil. The ovule pro- 

 duces within itself a female cell which may be fecundated 



FIG. 53. 



FIG. 54. 



FIG. 55. 



FIG. 53. Spikelet of wheat ; st stamens. 



FIG. 54. The same dissected ; x axis of spikelet ; g glumes ; 61, 62, 



flowering glumes ; B\, Bz, flowers displaced from the axis of flowering 



glumes ; ps palea ; a anthers ; / ovary. 

 FIG. 55. Flower of wheat, enlarged ; st stamens ; p pistil ; o ovary. 



by the male cell produced by the pollen (143). The 

 fecundated cell then grows to form a young plant the 

 embryo (55), and the parts of the ovule develop about it, 

 the whole forming the perfect seed. Unless the ovule is 

 fecundated, the seed very rarely develops. A flower 

 that contains no pistil, and hence no ovule, can of course 

 produce no seed. 



150. Pollination is the access of pollen (143) to the 

 stigma (144) the first step in the process of fecundation. 

 During a certain period, the surface of the stigma is 



