252 
HISTORY OF BRITISH FERNS. 
stems. These are quite dissimilar in their appearance, 
some being short, quite simple, and terminating in a cone¬ 
like head of spore-cases ; others being without fructification, 
taller, and producing several whorls of long, crowded, slen¬ 
der branches ; whilst a third kind, of ‘common though not 
constant occurrence/ produce whorls of branches and cones 
also. 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 any of the stems 
indifferently—at least as to external appearances—bear the 
fructification, all being of similar habit. 
The fertile stems grow about six inches high, and are 
quite branchless ; they are of a pale yellowish-green, having 
numerous joints, the large loose funnel-shaped sheaths 
produced at these points almost covering the stem, as 
usually described and figured; but in our specimens they 
are much less crowded, a space of from half an inch to an 
inch occurring between the adjoining sheaths. These 
sheaths are still paler-coloured than the stem, often almost 
white, with a dark ring below the teeth, which are awl- 
shaped, pale-brown, with pale-coloured membranous mar¬ 
gins ^ the teeth are about twenty—from twelve to twenty— 
