FILICES, 1 1 1 



peltate, fixed by the depressed centre; pinna and pinnules usually 

 auricled on the iipper side at base, mucronately serrate; veins free. 



* Fronds simply pinnate. 

 t Fronds long-stalked, lanceolate. 



3. A. acrostichoides Swz. (CHRISTMAS-FERN.) Stipes 

 6' 8' long, densely clothed below with pale-brown lanceolate 

 scales ; fronds i 2 high, 3' 5' broad ; pinnae linear-lanceolate, 

 somewhat falcate, half-halberd-shaped at the base, serrulate 

 with appressed bristly teeth ; the fertile ones contracted and 

 smaller, bearing contiguous sori near the middle, soon covering 

 the entire surface. A form with cut-lobed, often strongly fal- 

 cate pinnae, set obliquely to the rachis, and with the tips of 

 nearly all bearing sori, is the var. incisum Gray. {Nephrodium 

 acrostichoides Michx.) New England to Florida, Mississippi, 

 and northward. 



4. A. munitum Kaulf. Stipes 4' 12' long, chaffy like the 

 rachis with brown scales; fronds growing in a crown, i 4 

 long, tapering slightly toward the base ; pinnae numerous, 

 linear-acuminate, 3' 4' long, very sharply and often doubly 

 serrate, with appressed needle-like points; sori numerous, form- 

 ing a single row each side of the midrib half-way to the margin. 

 California and northward. 



ft Fronds scarcely stalked, linear-lanceolate. 



5. A. lonchitis Swz. (HOLLY-FERN.) Fronds 9' 20' long, 

 rigid ; pinnae i' or more long, broadly lanceolate-falcate or the 

 lowest triangular, strongly auricled on the upper side, the lower 

 obliquely truncate, densely spinulose-toothed ; sori contiguous 

 and near the margin. Canada and Wisconsin to Utah (Jones), 

 Castle Lake, Siskiyou County, California (Pringle), Mt. Peddo, 

 Washington Territory (Suksdorf}, and northward. 



** Fronds bipinnate or nearly so. 



6. A. mohrioides Bory. Stipes tufted, 2' 6' long, more or 

 less densely clothed with lanceolate dark-brown scales ; fronds 

 6' 12' long, 2' 3' broad, with numerous dense, often imbri- 

 cated, lanceolate pinnae, which are cut below into slightly 

 toothed oblong rhomboidal pinnules; teeth blunt or mucro- 

 nate ; texture coriaceous ; both surfaces naked ; rachis stout, 



