114 OUR NATIVE FERNS AND THEIR ALLIES. 



nalt's ]. Sm.) Northern United States and Canada. 



ttt Fronds bipinnate or tripinnatifid ; segments spinulose tootJied. 



15. 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 douWy serrate with spinulose teeth; indusia 

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

 tum Kaulf.) California, Oregon, British Columbia. 



16. 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 spinulosutn 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, 

 brown with a darker centre ; fronds broadly ovate or triangular- 

 ovate, oftenest tripinnate; pinnules lance-oblong, the lowest 

 often much elongated ; indusia smooth and naked. (A. dila- 

 tatum Swz., A. campylopterum Kunze., Nephrodium dilatattim 

 Desv., Lastrea dilatata J. Sm.) A dwarf form is var. dume- 

 torum. Canada and New England to Oregon. 



17. D. Boottii (Tuck.) Unde. Scales of stipes pale brown; 

 fronds elongate oblong or elongate lanceolate in outline; pin- 

 nules broadly oblong, very obtuse, the lower pinnatifid, the 

 upper and smaller merely serrate ; indusia minutely glandular. 



