Seed Plants : G}'mnosperms 



297 



it lacks a calyx and a corolla, ])ut its scales produce pollen and 

 therefore correspond to the stamens of a lily or rose. 



Each scale of the 

 ovulate cone has two 

 ovules, or young 

 seeds, on its upper 

 surface. At the time 

 when the pollen is 

 shed these scales 

 stand open, or are 

 separated from one 

 another, so that the 

 pollen falls on them 

 and slides down to 

 the bases of the 

 scales, where it comes 

 into contact with the 

 young ovules. Then 

 the scales of the cone 

 close up tightly, and 

 the pollen grains de- 

 velop pollen tubes. 



These grow down into the ovules and produce sperms which 

 finally fertiUze the eggs. As a result of fertilization, an 

 embryo is produced, and the ovule walls become the seed 

 coats: The growth of the pollen tube is very slow in coni- 

 fers, and it is only at the close of one or two years' growth 

 that the seeds mature and the ovulate cones die. Then the 

 drying out and spreading of the scales pcmiits the winged 

 seeds to fall out or to be blown out and carried to the ground. 



In many cases the seeds of conifers have hard waterproof 



Fig, 175. Spray of Austrian pine. At the left (above) 

 is a I -year-old and (below) a 2-year-old ovulate cone. 

 On the right is a cluster of staminate cones. 



