374 



THE SEED OF FINALES 



the sporangia. The sporophylls or their outgrowths often be- 

 come greatly enlarged, forming the hard, woody scales of the 

 cones (Fig. 258, B), or they may become fleshy and fuse, forming 

 a berry-like fruit, as in the juniper (Fig. 260, 7). When this 

 growth has been completed, the woody sporophylls or scales of 

 the strobilus dry out, and becoming hygroscopic, they spread 

 apart on dry days, thus permitting the scattering of the seeds 

 by the winds (Fig. 258, A). Many of the fleshy fruits are eaten 

 by birds and the hard nut-like seeds are distributed in this way. 



Fig. 258. A, mature strobilus of pine with open scales to permit the 

 •scattering of the seeds. B, scale from strobilus showing the winged seeds 

 ■developed from the two sporangia. C, a seed with wing-like outgrowth, 

 as it escapes from strobilus. 



The stages in the development of the seed, outlined above, are 

 very much prolonged in many of the pines. The microspores on 

 reaching the megasporangia, in the spring, develop only a short 

 tube cell during the first season and not until about the first of 

 July of the following season are the male and female gametes 

 mature and ready for fertilization. The seeds are matured during 

 the following season, over two years after the appearance of 

 the strobilus. Accordingly, three stages in the development 

 of the strobilus of megasporophylls may be seen on certain 

 species of pine in the early summer — very small ones that received 

 the microspores in the spring, larger ones in which fertilization 

 and the formation of the embryo is being effected and older stro- 

 bili in which the seeds are approaching maturity (Fig. 252). 

 When the conditions are favorable the embryo renews its growth. 



