Il6 OUR NATIVE FERNS AND 7^HEIK 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. (Nephr odium filix-mas 

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

 California, and Oregon. 



20. A. marginale Swz. Fronds smooth, 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 mar- 

 gtnale L., Nephrodium marginale Michx., Lastrea marginalis 

 J. Sm.) Northern United States and Canada. 



\\\ Fronds bipinnate or tripinnatifid; segments spinulose- toothed. 



21. A. rigidum Swz., var. argutum D. C. Eaton. Root- 

 stock 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- 

 tuin Kaulf.) California, Oregon. 



22. A. spinulosum Swz. Stipes with a few, pale-brown, 

 deciduous 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 spitmlosa Presl.) 

 Canada and Northern United States. 



Var. intermedium D. C. Eaton. Scales of the stipes few, 

 brown with a darker centre; fronds oblong-ovate, bi tripin- 

 nate; pinnae spreading, oblong-lanceolate, the lowest unequally 

 triangular-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. dilatatum Horneman. Scales of the stipes large, 



