MOSSES, LIVERWORTS, AND FERNS 279 
Modern equisetums live about open marshes, in sandy 
wastes, and along railroad embankments. They have hard, 
rough, siliceous stems, 
with small leaves that 
form sheaths about the 
joints of the stem (fig. 
217). In the most com- 
mon species of Lgiisetwin 
the sporophyll branch 
appears very early in the 
spring and produces at 
its tip the strobilus, or. 
cone, which bears the 
sporangia upon greatly 
reduced and transformed 
leaves (sporophylls). The 
bushy chlorophyll branch 
appears later and is the 
one which grows through- 
out the season, the sporo- 
pbyll branch disappearing 
as soon as the spores have 
been shed. The spores 
are attached to pecul- 
iar strap-like outgrowths 
known as elaters (driv- 
ers). The elaters are 
supposed to assist in dis- 
tributing the spores. 
The bushy fohage, or 
chlorophyll part of the 
plant, grows and depos- 
its food material which 
may be used the next 
season for the growth of 
the sporophyll branch. 
Fic. 218. A club moss (Lycopodium) 
The horizontal rootstock, with its roots, grows 
within or upon the humus. The upright branches 
(4) bear green leaves and strobili (str) (also 
called spikes or cones) in which spores are 
formed. At Cis shown one leaf from the strobi- 
lus, and upon this leaf is a sporangium. From 
the partially opened sporangium, spores escape. 
: B shows enlarged spores 
