160 FERNS OP GREAT BRITAIN. 



This species has three kinds of stem ; one bearing 

 fructification only, a second bearing both fruit and 

 branches, and a third with branches only. The fertile 

 stems are rigid, about six inches high, of a pale sea-green 

 hue, and with large, loose, and remarkably white sheaths, 

 having a brown rim at the base of the teeth. These are 

 long, narrow, and sharp, and are pale brown with white 

 edges. The oval catkin, composed of forty or fifty 

 scales, is at the top of the stem, and of a light brown 

 colour ; at first seated on the topmost sheath, but shortly 

 rising on a footstalk. It is matured in AprU. 



The branched fertile stems have sheaths midway in 

 size between those of the two other kinds of frond. 

 Whorls of branches are produced at the uppermost 

 joints. The cone, which is terminal on the stem, is 

 smaller than in the ordinary form of the fertile frond, 

 while the number of branches is fewer than in the 

 barren stem. 



The barren stem is erect, and from eighteen to twenty 

 inches in height ; it is very rough, and has about twenty 

 sharp ridges. A few joints at the base are vidthout 

 branches, the joints on the higher part of the stem pro- 

 ducing whorls of from ten to sixteen drooping branches, 

 which gradually spread so as to form larger circles. 

 The sheaths are smaller than those of the fertile stem, 

 clasping it more tightly, and have teeth similar in 

 colour, but shorter, fewer, and less prickly. The slender 

 branches are about four inches long, 3- or 4 -ribbed, and 

 their loose sheaths terminate in three or four short, 

 sharply-pointed teeth, tipped with pale brown. 



8. R Telmattia (Great Horsetail, Great Water Horse- 



