Polypodium. | XCIV. FILICES. 557 
strous states not unfrequently occur with the segments variously lobed or 
branched. 
In sheltered places, on trunks of old trees, walls, moist rocks, and shady 
banks, throughout Europe and temperate Asia, from the Mediterranean to 
the Arctic regions, and in North America and South Africa. Common in 
Britain. Fr. summer and autumn, 
2. P. Phegopteris, Linn. (fig. 1277). Beech Polypody, Beech Fern.— 
Rootstock creeping. Frondsrather slender, 6 inches to a foot high or rather 
more, including their long stalks, broadly ovate-lanceolate and acuminate in 
their general outline, once pinnate ; the segments deeply pinnatifid, narrow- 
lanceolate, gradually diminishing from the base to the end of the frond, 
and all, except sometimes the lowest pair, adhering to the main stem by 
their broad base. The midrib, principal veins, and margins of the frond 
more or less hairy on the under side, by which this species may be 
readily distinguished from the smaller specimens of Aspidium Thelypteris, 
which it sometimes resembles. Sori rather small, near the margins of the 
lobes. 
In moist situations, in hilly districts, in Europe and western Asia, from 
the Pyrenees and Alps to the Arctic regions, and in North America. In 
Britain, in western and northern England, Scotland, and Ireland. 7%. 
summer and autumn, 
3. BP. alpestre, Hoppe. (fig. 1278). Alpine Polypody.—Stock short, 
often forming several crowns. Fronds tufted, 1 to 3 feet high, twice 
pinnate; the segments numerous, oblong or lanceolate, deeply pinnatifid, 
and sharply toothed, the larger ones usually about half an inch long. 
Sori circular, without any indusium whatever; this character alone dis- 
tinguishes this plant from the smaller states of Asplenium Filix-foemina, 
and from some forms of Aspidium spinulosum, which it closely resembles 
in all other respects. 
In the mountains of Europe and western Asia, from the Alps and the 
Caucasus to the Arctic regions. In Britain, only in the Highlands of 
Scotland. Fr. summer. [P. flexile, Moore, is a variety found in the 
Forfarshire mountains, with very short stalks and segments. | 
4, P. Dryopteris, Linn. (fig. 1279). Oak Polypody, Oak Fern,— 
Rootstock creeping, rather slender. Fronds slender but erect, on long 
stalks, broadly triangular or rhomboidal in their general outline, the leafy 
part 4 to 6 inches long and at least as broad, twice pinnate, or rather, in 
the’ first instance, ternate; the lower pair of branches or pinnas on slender 
stalks, each often as large and as much divided as the rest of the frond ; 
the others much smaller and less divided, the terminal ones reduced to 
small lobes. Segments thin, light green, obtuse, slightly crenate, quite 
glabrous. Sori near the margins of the segments. 
In rather dry woods, in Europe and temperate Asia, from the Mediter- 
ranean to the Arctic regions, and in North America. Not uncommon in 
western, central, and northern England and Scotland, rare in North Ireland 
Fr. summer and autumn. PP. calcareum, Sw. (P. Robertianuwm, Hoffm.), 
is a variety of P. Dryopteris, of rather stouter growth, usually with rather 
less difference in size between the lower pair of pinnules and the succeeding 
ones, and is covered with a glandular meal. It occurs here and there, in 
more open rocky situations than the common form, and especially in lime- 
stone districts. 
