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, wemay 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) the gametophyte, 
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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