54 
FERNS. 
[Pteris. 
to the point of each pinna, one on each side of the midrib. In- 
dusium attached to very near the edge of the pinna, opening on the 
side nearest the midrib. 
While young the back of the lobe shows only the midrib and two irregularly- 
edged white covers ; afterwards these bend back and turn brown, and as in our 
species no leafy expansion appears outside the lines of theca;, but the cover seems 
to be the edge of the frond reversed, it might be taken at first sight for a Pteris, 
yet upon examination a narrow extension of the frond will be seen beyond the 
insertion of the indusiums. A curious variety of Blechnum boreale is found by 
Miss Beever, near Ambleside. Its lobes are much distorted, serrated, toothed, 
or deeply crenate. I have ventured to name and figure a portion of one of the 
fronds kindly sent me by Miss Beever. 
/3 ( stricta .) Frond linear, pinnules abbreviated, and with irregular margins. 
Sit.— O n sandy heaths, hedge-rows, stony places, &c. 
Hab. — Spread throughout England, Scotland, and Ireland, in the last country 
especially in the counties of Wicklow and Clare. It ascends to 700 yards in 
Cumberland, 800 in lorfarshire, and much higher on the Cairngorum Mountains, 
in Aberdeenshire, where it probably attains to situations of the height of 1200 or 
1300 feet, Mr. H. C. Watson. 
Geo. — Common in Germany, Denmark, Norway, Sweden, and N. W. coast of 
America. 
PTERIS, Linn. BRAKES. 
(wTjfif, a Fern; from a feather.) 
A, part of one of the divisions of the frond. B, the same magnified, shotring 
the continued indusium. C, transverse and perspective view of part of a pinnule. 
D, theca and spore. E, outer indusium magnified, showing its ciliated margin. 
F, transverse section of the rachis near the root. G, ditto of the creeping 
rhizoma. 
A very extensive genus, comprising no less than 120 species, most of them from 
warm climates. One species only is British. The fructification is borne in a 
continued line along the margin of the frond, which appears to be turned over 
so as to form a continued indusium, but which upon microscopic examination 
is seen to be of different and more delicate structure; an inner indusium is also 
present in ours and some other species, which many botanists consider a necessary 
character of a Pteris, and that its absence or presence might serve to divide the 
genus into two. 
