FILICES. 457 



3. P. Phegopteris Linn. : stipe pubescent, somewhat chaffy; frond bi- 

 pinnatifid, the two lower divisions deflexed ; segments linear-lanceolate, 

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

 sori solitary, marginal. P. connectile Mich. 



Shady woods. Throughout the U. S. July, Aug. 1].. Stipe 6 10 inches 

 long, minutely pubescent and a little chaffy. Frond triangular, 35 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 pinnae. Beech Polypody. 



*** Frond ternate, bipinnate. 



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

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

 ginal, at length confluent. P. calcareum Smith. Nephrodium Dryopteris 

 Mich. 



Wet woods. Arct. Amer. to Penn. July. 1\.. Rhizoma black, creeping and 

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

 wide, triangular, of a light green color. Sori small, light brown. 



Three-branched Polypody. 



2. ONOCLEA. Linn. 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. Indusium 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. obtusiloba Torr. : fertile frond deeply bipinnatifid ; segments obovate, 

 very obtuse ; the margin slightly recurved. O. oblusilobala Schk. ? Pursh. 



Moist woods. Can. to Flor. July. 1\.. 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 smoothish, dark brown, 

 resembling berries in two-rowed unilateral spikes. The var. obtustlobata 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 root with the common 

 variety. Sensitive Fern. 



3. ASPIDIUM. Swartz. Shield Fern. 



(From the Greek o<rjrf , 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 Swartz: stipe and rachis chaffy; frond pinnate; 

 pinns linear-lanceolate, acute, somewhat falcate, mucronate-serrulate, au* 



20 



