POLYPOD1UM DRYOPTERIS. 213 
POLYPO'DIUM DRYO'PTERTS. 
THIS Fern has uniformly borne the specific name of 
dryopteris, from being sometimes found among the 
moss about the root of Oak-trees, drys being the 
Greek for au Oak, and pteris for a Fern. It has been 
included, however, iu. various genera by different bo- 
tanists, being described by them as a Gymnocarpium, 
Lastreea, Phegopteris, and Polystichum. In English it 
is known as the Three-branched Polypody. 
Its root is black, widely creeping, thread-like, wavy, 
and slightly hairy, with numerous tufts of rootlets. 
Fronds from five to twelve inches high, with nearly a 
five-sided outline when laid flat ; but this form is not 
apparent in their growing posture, owing to their very 
flaccid growth. Stem slender, brittle, pale green, very 
smooth, with the exception of a few scales at the bottom ; 
dividing into three branches at the top, each branch 
about one-third the length of the stem, but the middle 
branch is rather the longest. The branches spread 
loosely and drooping, so as to be arched above. The 
branches really are large, pale, bright green leaflets, 
smooth, fine-textured, and cut into deep, oblong, blunt 
segments, wavy or toothed at their edge, and rather 
rolled back, and smooth, except having a slight downi- 
ness on the mid-vein. Instead of segments there are a 
few stalkless leaflets near the base of each branch. 
Each branch is triangular in its general outline. Mid- 
veiu wavy, with alternate side-veins, which fork, and 
