CHAPTER XVII 



PHYLUM XI. LEPIDOPHYTA 



THE LYCOPODS 



474. Here as in the Calamites we are dealing with a 

 phylum from which many of the forms have disappeared 

 through extinction, leaving only their fragmentary 

 fossils. Yet here again by a study of the plants that 

 have survived, and a comparison of their structure 

 with such fossil remains as have been found, we may make 

 out pretty clearly the nature of the plants that constitute 

 this phylum. 



475. Accordingly the Lycopods may be characterized 

 as chlorophyll-green, terrestrial plants, exhibiting two 

 generations in each life-cycle, viz. : (1) thegametophyte, 

 which is small, short-lived, and typically tuberous or 

 globose, with few rhizoids or none, and often dioecious; 

 the sexual organs are deeply sunken, and the sperms 

 are biciliated; (2) the sporophyte, which is large and 

 long-lived, with roots, a solid, continuous (not jointed) 

 stem, and many small spirally arranged or opposite 

 leaves, some of which, the sporophylls, with sporangia 

 in their axils, are in terminal cones. The spores are 

 mostly heterosporous. The tissues of Lycopods re- 

 semble those of Ferns and Calamites in both number 

 and kind. Their vascular bundles are essentially like 

 those of the Ferns (concentric), and in some cases are 

 separate, while in others they are consolidated into a 

 central compound bundle, surrounded by a mass of thick- 



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