SPERMATOPIIYTES : GYMNOSPERMS 



349 



danger of becoming confused and of forgetting that pollen 

 grains are asexual spores. 



229. Megasporophylls. — The strobili composed of mega- 

 sporopliylls become much larger than the others, forming 



Fig. 310. Pinus sylvestris, showing mature cone partly sectioned, and showinsr car- 

 pels (sq, sq^, sq^) with seeds in their axils (g), in which the embryos (em) may be 

 distinguished ; A, a young carpel with two megasporangia ; B, an old carpel with 

 mature seeds (ch), the micropyle being below (J/).— After Bessey. 



the well-known cones so characteristic of pines and their 

 allies (Fig. 308, «, Z>, c). Each sporophyll is somewhat 

 leaf-like, and at its base upon the upper side are two 

 megasporangia (Fig. 310). It is these sporangia which are 

 peculiar in each producing and retaining a solitary large 

 megaspore. This megaspore resembles a sac-like cavity in 



