260 HISTORY OF BRITISH PERNS. 



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 whorls of 

 branches from the upper joints will be 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 



