The beech ferns are often classed with the polypodies, because, like them,
they have no indusium; but in other ways they are more akin to the wood
ferns. Their stipes are not jointed to the root stock, nor are their sori
at the ends of the veins as in the polypodies. We here place them with
the wood ferns, retaining the familiar name _Phegópteris_ but giving
THELÝPTERIS as a synonym. The fruit-dots are small, round and naked,
borne on the back of the veins below the apex. Stipe continuous with the
rootstock. Veins free. (The name _Phegópteris_ in Greek means oak or beech
fern.)
(1) OAK FERN
_Phegópteris dryópteris_. THELÝPTERIS DRYÓPTERIS
Fronds glabrous, broadly triangular, ternate, four to seven inches broad,
the divisions widely spreading, each division pinnate at the base. Segments
oblong, obtuse, entire or toothed. Fruit-dots near the margin. Rootstock
slender and creeping from which fronds are produced all summer, in
appearance like the small, ternate divisions of the bracken.
This dainty fern has fronds of a delicate yellow-green, "the greenest of
all green things growing." Its ternate character is shown even in the
uncoiling of the fronds, the three round balls suggesting the sign of the
pawnbroker. The parts of the oak fern develop with great regularity, each
pinna, pinnule and lobe having another exactly opposite to it nearly
always. In rocky woods, common northward; also in Virginia, Kansas and
Colorado. A fine species for cultivation at the base of the artificial
rockery.
[Illustration: Oak Fern. _Phegopteris Dryopteris_]
(2) THE NORTHERN OAK FERN
_Phegopteris Robertiana. Phegopteris calcàrea_