90 OUR NATIVE FERNS AND THEIR ALLIES. 



3. A. emarginatum Hook. Stipes rather stout, nearly 

 black, polished ; fronds ovate or deltoid-pyramidal, bi tripin- 

 nate ; pinnules and upper pinnae ample, smooth, or nearly so, 

 rounded or even reniform, upper margin rounded, slightly in- 

 cised ; sori 2 5, transversely linear-oblong, subcontinuous. (A. 

 tenerum Torr.) California and northward. 



ft Fronds pilose, with ivhitish hairs. 



4. A. tricholepis Fee. Stipes smooth, polished, deep 

 black ; fronds oval ; pinnules roundish, moderately long-stalked ; 

 sori few (3 7), of unequal size ; indusia very velvety. (A. 

 dilatatum Nutt.) Western Texas. 



** Fronds dichotomously forked, with numerous pinna; spring- 

 ing from the upper side of the two branches. 



5. A. pedatum L. Stipes 9' 15' long, dark chestnut- 

 brown, glabrous ; fronds nearly circular in outline ; central pin- 

 nae 6' 9' long, i' 2' broad; pinnules triangular-oblong, short- 

 stalked ; sori roundish or transversely oblong. 



Vdr. rangiferinum Burgess. Pinnules longer-stalked and 

 deeply cleft into narrow-toothed lobes on the upper side. Mount 

 Findlayson, British Columbia. 



VIII. PTERIS L. BRAKE. 



Sori marginal, linear, continuous, occupying a slender fili- 

 form receptacle which connects the tips of the free veins. In- 

 dusium membranous, formed of the reflexed margin of the 

 frond. Name from Gr. TtrepiS, a fern, from Ttrepor, a wing, al- 

 luding to the prevalence of pinnate fronds. A cosmopolitan 

 genus containing 103 species. 



I. Eu PTERIS. Veins free, stipes tufted, indusium single. 

 * Lower pinna linear, undivided. 



i. P. longifolia L. Stipes 6' 12' long, clothed more or 

 less below with pale-brown scales; fronds i 2 long, 4' 9' 

 broad, oblong-lanceolate ; pinnae sessile, 2" 5" broad, linear, 

 entire ; veins close and fine, usually once branched ; indusium 

 yellowish brown. Florida. 



