FILICES. 109 



2. P. hexagonoptera Fee. Stipes 8' 18' long, stramine- 

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

 slightly pubescent, and often finely glandular beneath ; upper 

 pinnse 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. (Polypodhtm hexagon- 

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



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



3. P. alpestris Mett. Rootstock short, thick, erect or ob- 

 lique ; 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 sir.all, rounded, sub- 

 marginal. (Poly podium alpestre Hoppe, Aspidium alpestre 

 S\vz.) California and northward. 



*** f ron d s ternate, the three divisions petioled; rachis wingless. 



4. P. dryopteris 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. {Poly podium dryopteris L., 

 Xephrodium dryopteris Michx.) Northeastern United States to 

 Virginia, and westward to Oregon and Alaska. 



Var. Robertianum Dav. Stipes 6' 10' long, stramineous 

 when dry, 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 (Cathcari), Deco- 

 rah, Iowa (Holway), Northeast Territory (Macoini}. 



\ 2. GONIOPTERIS Presl. Veins pinnate, the lower veinlets 

 of contiguous groups uniting. 



5. P. tetragona Fee. Rootstock creeping; stipes erect, 

 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 pu- 

 bescent ; sori in rows near the midrib. Marion County, Florida 

 (Reynolds). 



