CALAMITES AND LYCOPODS 
369 
about 40 feet. In the island of Jamaica it is found in 
thickets 10 to 15 feet high. 
334. Description of the Sporophyte. The plant body 
(Fig. 267) consists of a horizontal, much-branched, under- 
ground stem, or rhizome, from which spring two kinds of 
sub-aerial branches sterile and fertile. The cells that 
FIG. 266. Equisetum fluviatile. Pure stand in shallow water, at Tully 
Lake, N. Y. (Photo by W. L. Bray.) 
compose the sub-aerial branches are, in many of the 
species (e.g., E. arvense), nearly or quite all formed by the 
close of the growing season, in the fall, so that in the 
following spring all that is necessary is the expansion of 
these cells, causing an elongation of the internodes and 
the appearance of the branch above ground in early 
spring. 
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