equisetum. 271 



whorls ; in very luxuriant plants, the branches are now 

 and then themselves branched upon a similar plan. 



Like the other species, this has a branching; under- 

 ground creeping stem, which is black, and produces whorls 

 of branched fibrous roots from its joints. The above- 

 ground stems are slender, and erect in their mode of 

 growth ; from two to three or four feet high ; deeply fur- 

 rowed, with a double row of elevated points along the 

 ridges, which are usually from eight to twelve, but some- 

 times fourteen in number. The sheaths are close, cylin- 

 drical, and striated like the stem, terminating:; in a number 

 of teeth equalling the stricc ; these teeth are long, slender, 

 awl-shaped, black with pale membranous margins, and 

 usually, but not always, persistent. The sheaths are, for 

 the most part, entirely black, but here and there they 

 occur with a narrow greyish ring, variable in position, 

 being sometimes central, and at other times near the base 

 or near the margin ; it is, however, we believe always, much 

 less decided and clearly defined than the pale-coloured 

 band on the sheaths of E. hjemale. 



The section of the stem differs from that of E. hjemale, 

 to which it presents a general resemblance, in being 

 smaller, showing fewer ridges, and having the cavities 



