278 niSTOEY OF British ferns. 



brandies not growing in whorls, but springing singly from 

 the joints, and having much similarity to the stem itself: 

 it is the erect form of the species, chieily, which thus 

 becomes branched. The stems grow about a foot high, 

 and, in what is taken as the typical plant, their surface 

 is very rough, and impressed with from four to ten furrows, 

 with alternating, rather prominent ridges, each ridge mar- 

 gined on both sides with a line of minute siliceous points, 

 which give it the appearance of being grooved, and impart 

 to it its peculiar roughness. The sheaths are slightly 

 enlarged towards their margin, ribbed like the stem, green 

 in the lower part, black above, and terminate in a fringe 

 of black teeth, equalling the ribs in number, with a broad 

 white membranous border, in form ovate, and tipped by a 

 deciduous bristle. Sometimes the contrast between the 

 black ring and teeth, and the white border to the latter, is 

 very conspicuous. 



A certain number of the stems, usually the most vigorous, 

 terminate in a cone of fructification. This is small, elliptic, 

 crowned by a prominent point or apiculus. It is usually 

 black, and sessile in the uppermost sheath, but sometimes 

 elevated on a short stalk. All the stalked cones we have 

 seen have been much paler in colour than the sessile ones. 



