EQTJISETUM. 231 



the lower part, terminate in an equal number of dark- 

 coloured awl-shaped teeth, which sometimes have a pale 

 membranous margin. The branches are four- to eight- 

 angled. 



Owing to the shallowness of the ridges and furrows, the 

 section of the stem shows a nearly smooth exterior outline, 

 and the cylinder of the stem is furnished only with a row 

 of minute cavities near the inner margin ; this cylinder is 

 very thin, compared with the diameter of the stem, the cen- 

 tral cavity being unusually large. The present plant, there- 

 fore, though it has been considered a variety of K palustre, 

 is most strikingly distinct from that species in the structure 

 of its stem. 



The fructification is produced by a portion of the 

 branches, in cones, at their apex; these cones are ovate 

 obtuse, and very frequently sessile in the uppermost sheath. 

 The scales are black, exceeding a hundred in number ; the 

 spore-cases are pale-coloured. Usually only the termina- 

 tion of the central stem bears fructification, but it some- 

 times happens, though rarely, that some of the uppermost 

 branches are also fertile. 



This plant is the most fodder-like of any of the Equise- 

 -Sj owing to its less flinty cuticle, but in this point of 



