POL Y PODIA CE^E. 1 1 5 



(A. spinnlosum, var. Boottii Gray.) New England, New York, 

 and northward. 



18. D. patula (Swz.) Unde. Stipes 8' 12' long, stra- 

 mineous, scaly at base; fronds pale green, i 2 long, 6' 12' 

 broad, ovate-lanceolate ; pinnse lanceolate or the lower sub- 

 deltoid ; rachis and both surfaces naked ; sori in rows midway 

 between edge and midrib; indusium conspicuous, naked. (Ne- 

 phrodiinn patulum Baker, N. Mexicanum Hook. Distributed 

 by Lemmon as A. Karwinskyanum.} Huachuca Mountains, 

 Arizona (Lemmon). 



XXIV. POLYSTICHUM Roth. 



Sori round, borne on the back or rarely at the apex of the 

 veins. Indusium flat or flattish, peltate, i.e., fixed at the centre 

 and becoming free all around the margin. Veins all free. 

 Name from Greek ito\v ?, many, and crrz;j;o?, a row. Includes 25 

 or more species. 



* Fronds simply pinnate. 

 t Fronds scarcely stalked, linear-lanceolate. 



1. P. lonchltis (L.) Roth. (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 (Suksdorf), and northward. 



t t Fronds long-stalked, lanceolate. 



2. p. acrostichoides (Michx.) Schott. (CHRISTMAS-FERN.) 

 Stipes 6' 8' long, 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 falcate 

 pinnse, set obliquely to the rachis, and with the tips of nearly 

 all bearing sori, is the var. incisum Gray. (Nephrodium acro- 

 stichoides Michx.) New England to Florida, Mississippi, and 

 northward. 



