FILICES. 109 



2. P. hexagonoptera (Michx.) Fee. Stipes stramineous, 

 naked; fronds as broad as long or nearly so, 7' 12' long, 

 slightly pubescent, and often finely glandular beneath ; upper 

 pinnae oblong, obtuse, toothed or entire, the very large, lowest 

 pinnae elongate and pinnately lobed ; sori near the margin or 

 some between the sinus and the midrib. (Pofypodnan hexagon- 

 opterum Michx.) Canada to Illinois, Kentucky, and Florida. 



** Fronds oblong-lanceolate, tripinnatifid ; rachis wingless. 



3. P. alpestris (Hoppe) Mett. Rootstock short, erect or 

 oblique; stipes 4' 10' long, with a few brown spreading scales 

 near the base ; fronds i 2 long, pinnae deltoid-lanceolate, the 

 lower ones distant and decreasing moderately ; pinnules oblong- 

 lanceolate, incised and toothed ; sori small, rounded, sub- 

 marginal. (Polypodium alpestre Hoppe, Aspidiiim alpestre 

 Swz.) California and northward ; Idaho (Sandberg). 



*** fronds ternate, the three divisions petioled ; rachis wingless. 



4. P. dryopteris(L.) Fee. (OAK-FERN.) Rootstock slender, 

 creeping; fronds broadly triangular, 4' 8' wide; the three 

 primary divisions i 2-pinnate ; segments oblong, obtuse, entire 

 or toothed ; sori near the margin. {Potypodium dryopteris L., 

 Nephrodium dryopteris Michx.) Northeastern United States to 

 Virginia, and westward to Oregon and Alaska. 



Var. Robertianum (Hoffm.) Dav. Stipes 6' 10' long, 

 stramineous, glandular; fronds 6' 8' long, 5' 7' wide, deltoid- 

 ovate in outline, bipinnate, lowest pair of pinnae far the largest, 

 pinnatifid or again pinnate; upper pinnae smaller, pinnatifid, 

 lobed, or entire ; sori copious, forming submarginal rows around 

 the segments. (P. calcarea Fee.) Minnesota (Cathcart), Deco- 

 rah, Iowa (Holway}, Northeast Territory (Macouti), Idaho. 



2. GONIOPTERIS Presl. Veins pinnate, the lower veinlets 

 of contiguous groups uniting. 



5. P. tetragona (Swz.) Fee. Rootstock creeping ; stipes 

 6' 18' long, naked or slightly villose ; fronds i 2 long, 

 6' 12 broad ; pinnae numerous, spreading 3' 6' long, the lowest 

 narrowed at the base and sometimes stalked, deeply pinnatifid ; 

 texture thinly herbaceous; rachis and under surface finely 

 pubescent ; sori in rows near the midrib. Marion County, 

 Florida (Reynolds). 



