FILICES. 1 1 1 



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

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



* Fronds simply pinnate. 

 \ 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, 



