244 HISTORY OF BRITISH FERNS. 



attributed to drought ; and seems to be one of those occa- 

 sional and inconstant variations to which plants are liable, 

 as they are influenced by the external circumstances of soil 

 or climate, or the peculiarities of the seasons. 



The barren stems of this species are very stately objects 

 when in a luxuriant condition of growth. They grow erect, 

 and are from six to seven feet or more in height, clothed 

 nearly to the bottom with spreading proximate whorls, those 

 on the stouter parts consisting of thirty to forty branches, 

 which are sometimes again branched. The upper whorls 

 have many fewer branches. The whorls are most crowded 

 towards the top of the stem, and there also the branches 

 are about the full length six or eight inches ; lower down 

 the stem the branches become shorter, and the whorls more 

 distant. The stems measure about an inch and a half in 

 diameter at the stoutest part, and from this point decrease 

 upwards, becoming very slender at the point. The surface 

 is smooth, with mere indications of about thirty faint lines 

 extending into the sheaths, and there becoming more appa- 

 rent. The sheaths set close to the stem, or nearly so, and 

 are half an inch long, green below, with a dark brown ring 

 at top, and divided at the margin into slender bristly teeth, 

 about half an inch long, dark brown, with paler membranous 



