20 POLYPODIACEAE. (FERN FAMILY) 



borne on a continuous vein-like marginal receptacle which connects the ends 

 of the veins. Indusium membranous, formed of the reflexed margin of the 

 leaf. Pteris. 



1. Pteridium aquilinum (L.) Kuhn, Decken's Reisen III. Bot. Ost-Afrika 11. 

 1879. Leaf often very large, the stipe and frond usually more than 1 m. in 

 length and often 2m.: frond broadly triangular, primary divisions stalked; 

 pinnae mostly pinnately lobed, with several to many rather short obtuse lobes, 

 and with a sometimes very long subentire apex. Frequent in the northern 

 half of the United States and in Canada. 



7. CHEILANTHES Swz. LIP FERN 



Small ferns, with 2-4-pinnate fronds, and the under surface either smooth 

 or variously covered with hair, wool, scales, or waxy powder. Ours belong to 

 the section in which the involucres are continuous around the greater part of 

 the margin of the very minute and bead-like ultimate segments, and the lower 

 surface of the fronds tomentose or scaly. 



Fronds tomentose beneath, but not scaly . . . . . . .1. C. Feei. 



Fronds very scaly beneath, tomentum scanty or none . . . . 2. C. Fendleri. 



1. Cheilanthes Feei Moore, Ind. Fil. 240. 1857. Fronds 5-12 cm. long, 

 ovate-lanceolate, tripinnate or bipinnate with pinnatifid pinnules; ultimate 

 segments less than a line long; upper surface scantily tomentose, the lower 

 surface matted with jointed woolly hairs: involucres herbaceous, very narrow. 

 C. lanuginosa. In dense tufts, on dry exposed rocks; Arizona to Colorado, 

 northward and eastward to the Great Lakes. 



2. Cheilanthes Fendleri Hook. Sp. Fil. 2: 103. 1858. Rootstock slender, 

 its scales loose and nerveless: frond 8-15 cm. long, tripinnate; ultimate pin- 

 nules rounded and entire, or obovate and 2-3-lobed, covered beneath with 

 broadly ovate acuminate *scales, which are sometimes sparingly ciliate at 

 base. In crevices of rocks; Colorado to Arizona and Texas. 



8. PELLAEA Link. CLIFF BRAKE 



Rock-loving small or medium-sized ferns with pinnate or pinnatifid leaves, 

 glabrous, having neither tomentum nor scales. Sori marginal and ultimately 

 in a confluent line. Involucre membranous and continuous around the pin- 

 nules. 



Fronds herbaceous or sub coriaceous; the veins clearly visible. 



Pinnae 6-8, membranous . . . . . . . . 1. P. Breweri. 



Pinnae 2-5, subcoriaceous . . . . . . . . 2. P. occidentalis. 



Fronds coriaceous; the veins not perceptible. 



Closely tripinnate, 4-5 cm. long . . . . . . . 3. P. densa. 



Bipinnate, 10-20 cm. long 4. P. Wrightiana. 



1. Pellaea Breweri DC. Eat. Proc. Am. Acad. 6: 555. 1866. Rootstock 

 short, densely covered with narrow fulvous chaff: fronds membranous, 

 5-15 cm. long, simply pinnate with mostly unequally 2-lobed pinnae; the seg- 

 ments obtuse, in the fertile frond narrower: indusium continuous, pale: veins 

 repeatedly forked. From California to Utah and Colorado. 



2. Pellaea occidentalis (E. Nels.) Rydb., Underw. in Our Native Ferns 98. 

 1900. Rootstock short and thick, densely covered with rusty hair-like scales: 

 stipes caespitose, 1-4 cm. long, dark brown, glabrous, shining, very slender: 

 fronds 3-8 cm. long, oblong, simple-pinnate; pinnae 2-5 pairs, oblong, mostly 

 obtuse, dark green, shining, firm and somewhat coriaceous, entire, or the 

 lower with 1 or 2 lobes at the base: indusium broad, wholly covering the sori. 

 P. atropurpurea in part. (P. pumila Rydb. Mem. N. Y. Bot. Gard. 1:4. 

 1900.) Colorado to Montana, and west to Washington. 



3. Pellaea densa (Brack.) Hook. Sp. Fil. 2: 150, t. 125. 1858. Rootstock 

 slender, chaffy with blackish scales: stipes densely tufted, wiry, very slender, 



