CALAMITES AND LYCOPODS 



385 



sterile. The lower sporangia are larger than the upper 

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

 megasporangia, and the leaves are megasporophylls. The 



FIG. 281. Selaginella Martcnsii. a, vegetative branch; &, portion of 

 the stem, bearing cones (x)\ c, longitudinal section of a cone, showing 

 microsporangia (mic. sp.} in the axils of microsporophylls, and megaspor- 

 angia in the axils of megasporophylls; d, microsporangium with micro- 

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

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

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

 opened, showing the four megaspores. 



smaller sporangia (microsporangia) are subtended by 

 microsporophylls, and bear numerous small spores (micro- 

 spores). In some species the two kinds of sporophylls 

 25 



