POLLINATION 



123 



small cones is a stamen (sporophyll) bearing sacs (microspor- 

 angia) filled with great quantities of yellow pollen grains 

 {microspores) which fall in showers and are scattered by the 

 wind. These pollen grains are provided with liattened exten- 

 sions of the cell-wall, forming wings for their ready support in 

 the air. 



t<56 



FiQ. 82. — a, cluster of staminate cones; b, pollen grain; c, pistillate cone; d, scale from 

 pistillate cone showing two ovules. 



Some of the pollen is canght in the pistillate cones and falls 

 upon the exposed ovules. The scales close and the pollen grain 

 produces a delicate tube which penetrates the ovule, reaches the 

 egg and results in fertilization similar to that described for the 

 angiosperm. (Chapter VI.) This process cannot be followed 

 except by the study of carefully prepared slides with the aid 

 of the microscope. However, the interval of time between pol- 

 lination and the maturity of the seed is much greater than in 

 most angiosperms. The seed cone enlarges rapidly, but tlie 

 seeds are not mature until late in the summer of the following- 

 year. 



