570 THE FERN FAMILY. — —_[Cystopteris, 
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. 1812). 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. Rare 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. dvensis, 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. 1813). Huropean 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 4 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 
