POLYPODIACEAE. 



421 



1. Anchistea virginica 



(L.) Presl. Virginia Chain- 

 fern. (Fig. 457.) Rootstock 

 stout, chaffy. Petioles stout, 

 lo-lio long, nearly or quite 

 naked, dark-colored below ; 

 blades oblong-lanceolate, acute, 

 narrowed at tlie base, l°-2° 

 long, 6'-9' wide, once pinnate; 

 pinnae linear-lanceolate, usually 

 alternate, or some of them op- 

 posite, leathery, glabrous, acu- 

 minate, sessile, 2^-6' long, 

 deeply pinnatifid into ovate or 

 oblong obtuse segments, their 

 margins minutely serrulate. 

 [Blechnum virginicum L. ; 

 Woodwardia virginica J. E. 

 Smith.] 



Frequent in the larger fresh- 

 water marshes. Native. Eastei-n 

 North America. 



8. ASPLENIUM L. 



Large or small ferns with entire lobed pinnate, 2-3-pinnate, or pinnatifid 

 leaves, and linear or oblong sori oblique to the midribs or rachises. Leaves 

 mostly uniform. A^eins free. Indusia straight or curved, opening toward the 

 midribs. [Ancient Greek name; some species were supposed to be remedies 

 for diseases of the spleen.] A genus of some 400 species, of very wide 

 geographic distribution. Type species: Asplenium Trichomanes L. 



Leaves once pinnate. 



Pinnae 6-8 pairs ; stipes blacljish only at the base. 1. A. dentatum. 



Pinnae 20-40 pairs ; stipes black, shining. 2. A. hetcrochroum. 



Leaves finely twice or thrice pinnate. 3. A. moutcvvnlcnisc. 



