^60 HISTORY 03? BRITISH FERNS. 
resemblance consists in both growing up at the same time, 
and both putting out whorls of deflexed branches, less 
numerous certainly on the fertile stems; but in other 
respects they differ, as, for instance, in the growth of the 
apices of the fronds. The fertile ones, terminating in a 
catkin which soon perishes, become blunt-topped, while the 
barren ones continue to elongate at the point, and so 
become somewhat pyramidal. The barren stems are also 
more slender than the fertile ones, and have less inflated 
sheaths. It will thus appear, that this species, in its habit 
of growth, holds a middle rank between that group in 
which the fertile and barren stems are successive and quite 
dissimilar, and that group in which they are simultaneous 
and present no appreciable difference of structure. Some¬ 
thing of the same kind occurs in E. umbrosum. 
The fertile stems, when they first shoot up, are almost 
quite simple, and a few of them remain so, perfecting their 
cone-like head, and then perishing. More usually, by the 
time the catkin has become fully grown, the wdiorls of 
branches from the upper joints will he seen protruded to 
the length of from half an inch to an inch or rather more. 
Two, three, or four, rarely more, whorls of branches are 
thus produced from the uppermost joints of the stem, and 
