164 



PLANT STRUCTURES 



gradation between ordinary foliage leaves and distinct 

 sporophylls. ' 



The sporangia are borne either by distinct sporophyils 

 or by the ordinary foliage leaves near the summit of the 

 stem. At the base of each of these leaves, or sporophylls, 

 on the upper side, is a single sporangium (Fig. 137). The 

 sporangia are eusporangiate in origin, and as the spores are 

 all alike, Lycopodiitm has the same homosporous-eusporaii- 

 giate combination noted in Equisetales and in one of the 

 groups of Filicales. 



89. Selaginella. This large genus contains the smaller, 

 more delicate Club-mosses, often being called the " little 

 Club-mosses." They are especially displayed in the trop- 



FIG. 138. Selaginella, showing general spray-like habit, and dangling leafless stems 

 which strike root (rhizophores). From "Plant Relations." 



ics, and are common in greenhouses as delicate, mossy, 

 decorative plants (Fig. 138). In general the sporophylls 

 are not different from the ordinary leaves (Fig. 139), but 

 sometimes they are modified, though not so distinct as in 

 certain species of Lycopodium^ 



