250 HISTORY OF BRITISH FERNS. 



branches very frequently produce a series of two to five 

 secondary branches at their second joints. The colour of 

 the main stem is a very pale, that of the branches a de- 

 licate green. The sheaths of the branches, in this and 

 some other species, furnish excellent marks for discri- 

 mination. 



The fertile stem is erect, simple, from nine inches to a 

 foot or more high, succulent, pale brown, and smooth. 

 From each of the numerous joints arises a large loose 

 funnel-shaped sheath, the upper ones being largest ; they 

 are distinctly striated, and terminate in thirty to forty long, 

 slender, and, according to Hooker, two-ribbed, teeth. The 

 sheaths are pale greenish brown below, darker brown above. 

 The catkins are large, between two and three inches long ; 

 the scales, often numbering four hundred, are arranged in 

 whorls, of which the lower ones are usually very distinct. 

 The scales and spore-cases resemble those of the allied 

 kinds, 



A section of the barren stem of this species shows an 

 outer surface without ridges and furrows, and in the very 

 narrow cylinder of the stem occur two circles of cavities, 

 the outer one consisting of larger openings, while those of 

 the inner are more minute, and alternating with the larger. 



