SPEBMATOPHYTES : GYMKOSPEEMS 



349 



danger of becoming confused and of forgetting that pollen 

 grains are asexual spores. 



•229. Megasporophylls. — The strobili composed of mega- 

 sporophylls become much larger than the others, forming 



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

 pels (sg, sg 1 , sq 2 ) with seeds in their axils (g), in which the embryos (em) may he 

 distinguished ; .-1. a young carpel with two megasporangia ; _B, an old carpel with 

 mature seeds (chi, the micropyle being below (Ji\— After Besset. 



the well-known cones so characteristic of pines and their 

 allies (Fig. 308, a, b, 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 



