HORSETAILS. 



I8 9 



plant begin to appear above the ground. One of these is shown 

 in fig. 237. This has a much more slender stem and is pro- 



Fig. 236. 



Spore of equisetum with elaters un- 

 coiled. 



Fig. 235. 



Spore of equisetum 

 with elaters coiled up. 



vided with numerous branches. If we ex- 

 amine the stem of this shoot, and of the 

 branches, we will see that the same kind of 

 leaves are present and that the markings on 

 the stem are similar. Since the leaves of 

 the horsetail are membranous and not green, 

 the stem is green in color, and this per- 

 forms the function of carbon conversion. 

 These green shoots live for a great part of 

 the season, building up material which is 

 carried down into the underground stems, 

 where it goes to supply the forming fertile 

 shoots in the fall. On digging up some of 

 these plants we see that the underground 

 stems are often of great extent, and that 

 both fertile and sterile shoots are attached 

 to one and the same. 



384. The scouring rush, or shave grass. 

 Another common species of horsetail in 

 the Northern States grows on wet banks, 

 or in sandy soil which contains moisture 

 along railroad embankments. It is 

 the scouring rush (E. hyemale), so 

 called because it was once used for 

 polishing purposes. This plant like 

 all the species of the horsetails has 



Fig. 237. 

 Sterile plant of horsetail (Equi- 



