2 POLYPODIACEAE. 



1. PHEGOPTERIS. Beech Fern. 



Medium sized or small ferns ; leaves twice to thrice pinnate or 

 ternate; leaf -stalk continuous with the rootstock; fruit dots 

 small, round, without an indusium, borne on the backs of the 

 veins below or near their ends; veins free or reticulate. 



Phegopteris dryopteris (L.) Fee. Rootstock slender, horizontally creeping; 

 petioles 15-25 cm. tall, pale straw-colored, shiny, bearing a few brownish 

 scales toward the base; blades broadly triangular in outline, 10-20 cm. wide, 

 ternate, the lateral primary divisions bipinnate, the terminal usually tripinnate, 

 all naked at the base; pinnae oblong, 2-5 cm. long, glabrous, pinnately-cleft 

 or divided into 15-25 obtuse lobes; fruit dots near the margin, on the ends of 

 free veins. Common in rich woods. 



2. PTERIDIUM. 



Large, mostly coarse ferns, with variously divided leaves; 

 fruit dots marginal, linear, continuous on a slender thread-like 

 receptacle which connects the tips of free veins ; false indusium 

 membranous, formed of the reflexed margin of the leaf. 



Pteridium aquilinum pubescens Underw. Bracken or Brake. Rootstock 

 stout, black, subterranean, horizontally-creeping; petioles 30-90 cm. high, 

 erect, pale-green or straw-color; leaf-blades 60-120 cm. long, 30-90 cm. wide, 

 glabrous above, pubescent beneath, ternate, the three branches each bipinnate; 

 pinnules oblong, acutish, mostly entire, the uppermost coalescent, the lower 

 more or less lobed. Common in coniferous woods, otherwise infrequent. 



3. PELLAEA. 



Small and smooth tufted rock ferns; leaves 1-4 times pinnate, 

 the petioles mostly dark colored ; fruit dots terminal on the veins, 

 roundish but often confluent in a continuous band ; false indusium 

 continuous, broad, formed by the reflexed margins of the pinnules. 



Pellaea densa (Brack.) Hook. Densely tufted, 10-20 cm. high; petioles 

 dark brown, longer than the blades; blades 3-6 cm. long, ovate or ovate- 

 oblong, tripinnate; leaflets crowded, linear-lanceolate, 6-12 mm. long, mucro- 

 nate, entire on the fertile leaves, serrate on the sterile ones. On cliffs and 

 among boulders, Blue Mountains and top of Cedar Mountain, Idaho. 



4. CHEILANTHES. 



Mostly pubescent or tomentose rock-loving and small ferns 

 with much divided leaves; fruit dots on or near the ends of the 

 veins, at first small and distinct, afterwards crowded; sporangia 

 often concealed in the scales or hairs which in many species 

 cover the segments. 



The species occurring within our limits have the ultimate 

 segments of the pinnae very small and circular in form and the 



