Il6 OUR NATIVE FERNS AND THEIR ALLIES. 



nate; pinnules oblong, smooth, polished beneath, the larger 

 ones pinnately incised ; sori large, near the midvein, commonly 

 on the lower half or two thirds of the segment ; indusia firm, 

 smooth; rachis more or less chaffy. (Nephrodium filix-mas 

 Rich., Lastrea filix-mas Presl.) Canada to Colorado, Arizona, 

 California, and Oregon. 



20. D. marginalis (L.) Gray. Fronds nearly coriaceous 

 in texture, 6' 2 long, ovate-oblong ; pinnae lanceolate, broadest 

 just above the base; pinnules oblong or oblong-falcate, entire^ 

 or crenately toothed ; sori close to the margin. (Polypodium 

 margtnale L. , Nephrodium marginale Michx., Lastrea margi- 

 nalis J. Sm.) Northern United States and Canada. 



ttt Fronds bipinnate or tripinnatijid ; segments spinulose toothed. 



21. D. rigida (Hoffm.) Unde., var. arguta (Kaulf.) Unde. 

 Rootstock short, stout ; fronds in a crown on chaffy stalks, half- 

 evergreen, smooth above, paler and more or less glandular be- 

 neath, i 3 high, ovate-lanceolate or triangular-lanceolate, 

 bipinnate; pinnae broadly oblong-lanceolate, the lowest ones 

 broadest, scarcely shorter than the middle ones; pinnules ob- 

 long, incised or doubly serrate with spinulose teeth ; indusia 

 firm, convex, the edge bearing short-stalked glands. (A. argu- 

 turn Kaulf.) California, Oregon, British Columbia. 



22. D. spinulosa (L.) Ktze. Stipes with a few, pale, de- 

 ciduous scales; fronds ovate-lanceolate, bipinnate, the pinnae 

 oblique to the rachis, elongate-triangular, the lower pairs 

 broadly triangular; pinnules oblique to the midrib, connected 

 by a very narrow wing, oblong, incised, or pinnatifid with lobes 

 spinulose toothed ; indusia smooth without marginal glands. 

 (Nephrodium spinulosum Desv., Lastrea spinulosa Presl.) 

 Canada and Northern United States. 



Var. intermedia (Willd.) Unde. Scales of the stipes brown 

 with a darker centre ; fronds oblong-ovate, bi tripinnate ; 

 pinnae spreading, oblong-lanceolate, the lowest unequally tri- 

 angular-ovate; pinnules crowded, pinnately divided; margin 

 of indusium denticulate and beset with stalked glands. (A. in- 

 termedium Willd., A. Americanum Dav.) Canada to Tennes- 

 see. 



Var. dilatata (Hoffm.) Unde. Scales of stipes large, 



