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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