! BRITISH HORSETAILS. 
109 
, ting in a cone-like head of spore-cases. The latter are taller, 
and produce several whorls of long, crowded, slender 
branches; whilst a third kind produce both whorls of branchy 
and codes. In the production of these three kinds of stems it 
serves to connect, through E. sylvaticum, that group in which 
the fertile and barren stems are successive and altogether 
unlike, with that in which the stems indifferently bear the 
fructification. 
. The fertile stems grow about six inches high, and are quite 
branchless; they have numerous joints, the large loose funnel- 
shaped pale-coloured sheaths produced at these points, often 
' almost covering the stem. The teeth, which terminate the 
sheaths, are awl-shaped, pale brown, with pale-coloured 
^membranous margins, and nnmber from twelve to twenty, 
; equalling the ribs. The fructification forms a moderate-sized, 
. terminal, oval, cone-like head. 
The barren stems grow erect, eighteen inches or more in 
height, and have on their surface about twenty sharp ridges, 
, with corresponding farrows, the ridges being coated with 
prominent silicious warty particles, so that the stems are 
vprv rough. The few lower joints are without branches, but 
" ‘ part of the stem produce whorls of from 
limple, and at first droop- 
ng. The sheaths of these 
barren stems are much smaller than those of the fertile, less 
funnel-shaped, and more closely set to the stem, and their 
teeth are also fewer, shorter, and blunter. The branches ate 
’ ' ■* r four-ribbed, and have loose sheaths, which _ 
these cases, however, t^ ^ 
that produced by the ordinary barren stems, and the c 
smaller than those produced by the ordinary fertile ste 
The section of the stem shows oh the exterior a sei 
sharp ridges with angular furrows; the central cavity rathei 
exceeds a third of the v ’ 1 tm f| ’’ f | |j| 
mber of branches i 
ridges, and s 
tide also opposite f*" 
intiful in m< 
Probably this species is tolerably plentiful in moist shady 
roods, which are the situations it affects: but it has as yet 
