CHAPTER XI 



HORSETAILS AND CLUB-MOSSES 

 HORSETAILS 



112. General characters. The horsetails or equisetums 

 are represented to- 

 day by only twenty- 

 five species ; but 

 during the Coal- 

 measures the spe- 

 cies were very nu- 

 merous, and some 

 of them were great 

 trees, forming a 

 conspicuous part of 

 the forest vegeta- 

 tion. They grow 

 in moist or dry 

 ground, sometimes 

 in great abun- 

 dance, and have 

 such a character- 

 istic appearance 

 that they cannot 

 be mistaken. 



The stem is slen- 

 der and conspicu- 

 ously jointed, the 



joints Separating FIG. 189. Equisetum: showing the jointed and fluted 



.. ._,. 1 QO\ stem, the sheath of minute leaves at each joint, 



easily (r Ig. 189) . strobili in various stages, and some young branches, 



197 



