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 Martensii. a, vegetative branch; b, portion of 
the stem, bearing cones (#); 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; *, 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 
