FILICES. 457 



3. p. Phegopteris Linn. : stipe pubescent, somewhat chaSy ; frond bi- 

 jiinnatifid, the two lower divisions deflexed ; segments linear-lanceolate^ 

 obtuse, entire, ciliate, the lowermost ones adnate-decurrent ; veins hairy ; 

 sori solitary,, marginal. P. cnnneciile Mich. 



Shady woods. Throughout the U. S. July, Aug. %. — Stipe 6 — 10 inches 

 long, minutely pubescent and a little chaffy. Frond triangular, 3 — 5 inches 

 long. Sort minute, mostly 4 on each segment. Identical with the foreign plant, 

 and differing from the preceding chiefly in its smaller size, pubescent stipe, and 

 more closely approximated pinnas. Beech Polypody. 



*** Frond ternate, bipinnaie. 



4:.JtkDryopteris Linn. : frond ternate ; the divisions bipinnate, spread-- 

 ing and deflexed ; segments oblong, obtuse, somewhat crenate ; sori mar- 

 ginal, at length confluent, P. calcarcum Sniit/i. Nephrodium Dryopteris 

 Mich. 0^ 



Wet woods. Arct. Amer. to Penn. July. %. — Rhizoma black, creeping and 

 slender. Stipe 6 — 12 inches long, erect, slender, smooth. Frond 4 — 6 inches 

 'Vide, triangular, of a light green color. Sori small, light brovra. 



Three-branched Polypody. 



2. ONOCLEA. i>z?m.— Sensitive Fern. 

 (An ancient Greek name, applied to this genus.) 



Sterile frond deeply pinnatifid ; the segments sinuous or pin- 

 natifid, with reticulated veins. Fertile frond bipinnate, small; 

 the segments contracted, with their margins revolute, forming 

 a general involucre and resembling berries. Sori 4 — 6, con- 

 fluent. Indusitim lateral, cucullate, thin and membranaceous. 



0. sensibilis Linn. : sterile frond pinnate ; pinnas lanceolate, acute, la- 

 ciniate, upper ones united at base ; fertile frond bipinnate, with the seg- 

 ments recurved and globosely contracted, resembling a compound spike. 



var. flbkisiloba Torr. : fertile frond deeply bipinnatifid ; segments obovate, 

 very obtuse ; the margin slightly recurved, O. obtusilobata Schk. ? Pursk. 



Moist woods. Can. to Flor. July. %. — Stipe 8 — 12 inches long, angular, a 

 little chaffy at the base, elsewhere smooth. Sterile frond 8 — 12 inches long, 

 triangular, deeply pinnate, smooth. Fertile frond 3 — 6 inches long, nearly erect ; 

 the contracted and somewhat triangular-globose segments sruoothish, dark brown, 

 resembling berries in two-rowed unilateral spikes. The var, obtusilobata is quite 

 rare, and is said by Torrey to have been hitherto obtained in only three local- 

 ities. In one of these it was found growing on the same toot with the common 

 variety. Sensitive Fern. 



3. ASPIDIUM. Sioartz.—Shield Fern. 



(From the Greek aairti^ a shield ; in allusion to the form of the indusium.) 



Sori roundish, scattered. Indusium orbicular, fixed by the 

 centre, or reniform and fixed at the sinus. 



* Frond pinnate. 



1 , A. acrostichoides Sioarbz : stipe and rachis chafiy ; frond pinnate ; 

 pinnae linear-lanceolate, acute, somewhat falcate, mucronate-serrulate, au- 



20 



