570 THE FERN FAMILY. [Cystopterit. 



In moist, alpine situations, in northern and Arctic Europe, Asia and 

 America, and in their great mountain-ranges. In Britain, only on a 

 few of the lofty mountains of Scotland. Fr. summer. 



XV. WOODSIA. WOODSIA. 



Small, tufted, pinnately-divided Ferns, with brown scarious scales or 

 hairs on the under surface. Sori circular, surrounded by or intermixed 

 with a fringe of chaffy hairs, proceeding from the minute indusium 

 concealed under the sorus. 



A small- genus, still more strictly confined than the last to high 

 northern or southern latitudes, or to great elevations. 



1. W. ilvensis, Br. (fig. 1312). Alpine W. Stock densely tufted. 

 Fronds spreading, 2 to 4 or rarely 6 inches long, twice pinnate, oblong- 

 lanceolate in outline ; the longer primary pinnas in the middle of the 

 frond, 6 to 9 lines long, the lower ones decreasing ; all pinnate or 

 pinnatifid, with small obtuse segments, rather thick, green and glabrous, 

 or hairy above, more or less covered underneath with brown scarious 

 scales or chaffy hairs. 



On alpine rocks, in northern and Arctic Europe, Asia, and America, 

 and on their great mountain-chains. Bare in Britain, and only in the 

 mountains of Scotland, northern England, and North Wales. Fr. 

 summer. W. hyperborea, Br., usually considered as a distinct species, 

 but probably only a variety of W. ilvensis, differs in its more tender 

 texture, a greener colour, the segments shorter and less deeply divided, 

 with more rounded lobes, and the scarious scales less numerous, 

 narrower and paler-coloured. Its range is nearly the same as that of 

 the ordinary form, but it is generally more rare. 



XVI. TRICHOMANES. BRISTLE FERN. 



Delicate, half -pellucid Ferns, usually of a dark green. Fructification 

 consisting of little cup-shaped involucres, sessile upon or partly im- 

 mersed in the edge itself of the frond. In the centre of the involucre 

 is a little bristle, often projecting beyond it, round the base of which 

 are attached the minute capsules or spore-cases. 



A large genus, widely spread over the warmer regions of the globe, 

 but more especially in tropical America. 



1. T. radicans, Sw. (fig. 1313). European B. Rootstock creeping, 

 often to a considerable extent. Fronds usually 6 to 8 inches high, 

 including the rather long stalk ; broadly ovate-lanceolate in general 

 outline, twice or thrice pinnate, of a dark green, with rather stout 

 stalks and branches. Segments numerous and crowded, thin, pellucid, 

 oblong, more or less toothed, narrowed at the base. Involucres in the 

 axils of the small ultimate segments or lobes, cylindrical, about a line 

 long, the central bristle projecting to 1 line more. 



In moist, sheltered, shady places, widely distributed over the tropical 

 and hotter regions of both hemispheres, but in Europe only in a few 



