658 FILICES. (ferns.) 



1. POLYPODIUM, L. Polypody. (PI. 15.) 



Fruit-dots round, naked, arranged on the back of the frond in one or more 

 rows each side of the midrib or central vein, or irregularly scattered, each borne 

 in our species on the end of a free veinlet. Rootstocks creeping, branched, often 

 covered with chaffy scales, bearing scattered roundish knobs, to which the stipes 

 are attached by a distinct articulation. (Name from 7ro\u, many, and novs,foot, 

 alluding to the branching rootstock ) 



1 . P. Vlllgare, L. Pronds evergreen, oblong, smooth both sides, 4' - 10' high, 

 simply and deeply pinnatifid ; the divisions linear-oblong, obtuse or somewhaf 

 acute, remotely and obscurely toothed ; veins once or twice forked ; fruit-dots 

 large, midway between the midrib and the margin. — Rocks: common. July. (Eu.) 



2. P. incanum, Swartz. Fronds evergreen and coriaceous, oblong, 2'- 

 6' high, grayish and very scurfy underneath with peltate scales, simply pinnatifid ; 

 the divisions oblong-linear, obtuse ; fruit-dots rather small, near the margin ; veins 

 forking, free in the N. American plant ! — Rocks and trunks of trees, Virginia 

 and Ohio to Illinois, and southward. Aug. 



2. ADIANTUM, L. Maidenhair. (PI. 16.) 



Fruit-dots marginal, short ; borne on the under side of a transversely oblong, 

 crescent-shaped or roundish, more or less altered margin or summit of a lobe or 

 tooth of the frond reflexed to form an indusium : the sporangia attached to the 

 approximated tips of the free forking veins. — Main rib (costa) of the pinnules 

 none, or at the lower margin. Stipes black and polished. (The ancient name, 

 from a privative and diaivco, meaning unwetted, the smooth foliage repelling 

 rain-drops. ) 



1. A. pedatum, L. Frond forked at the summit of the upright slender 

 stalk (9'- 15' high), the recurved branches bearing on one side several slender 

 spreading divisions, which bear numerous triangular-oblong and oblique short- 

 stalked pinnules ; these are as if halved, being entire on the lower margin, from 

 which the veins all proceed, and cleft and fruit-bearing on the other. — Rich, 

 moist woods. July. — A delicate and most graceful Fern. 



3. PTEBIS, L. Brake or Bracken. (PI. 16.) 



Sporangia in a continuous slender line of fructification, occupying the entire 

 margins of the fertile frond, and covered by its reflexed narrow edge, which 

 forms a continuous membranaceous indusium, attached to an uninterrupted 

 transverse vein-like receptacle which connects the tips of the forked and free 

 veins. — Fronds once to thrice pinnate or decompound. (The ancient Greek 

 name of Ferns, from Trrepov, a wing, on account of the prevalent pinnate or 

 feathery fronds.) 



1. P. aquilina, L. (Common Brake.) Frond dull green (2° -3° wide), 

 ternate at the summit of an erect stout stalk (l°-2° high), the widely spreading 

 branches twice pinnate ; pinnules oblong-lanceolate ; the upper undivided ; the 

 lower more or less pinnatifid, with oblong obtuse lobes, margined all round with 

 the indusium. — Thickets and hills : common. Aug. (Eu.) 



