CALAMITES AND LYCOPODS 



38s 



sterile. The lower sporangia are larger than the upper 

 ones, and bear four large spores (megaspores). They are 

 megasporangia, and the leaves are megasporophylls. The 



Fig. 281. — Selaginella Martensii. a, vegetative branch; b, portion of 

 the stem, bearing cones \k); c, longitudinal section of a cone, showing 

 microsporangia {mic. sp.) in the axils of microsporophyUs, and megaspor- 

 angia in the aMls of megaspoiophylls; d, microsporangium with micro- 

 sporophyll; e, microspores;/, pornon of wall of sporangium, greatly magni- 

 fied; g, megaspore; h, microsporangium opened, and most of the micro- 

 spores scattered; i, megasporangium, with megasporophyU; k, same, 

 opened, showing the four megaspores. 



smaller sporangia (microsporangia) are subtended by 

 microsporophyUs, and bear numerous small spores (micro- 

 spores). In some species the two kinds of sporophylls 

 25 



