98 OUR NATIVE FERNS AND THEIR ALLIES. 



1. P. Breweri D. C. Eaton. Stipes densely tufted, cov- 

 ered with narrow, crisped, fulvous chaff ; fronds 2' — 6' long, 

 simply pinnate, the pinnae short-stalked, 6 — 8 pairs, membra- 

 nous, mostly 2-parted, the upper segment larger ; segments ob- 

 tuse, in the fertile frond narrower; indusium continuous, pale; 

 veins repeatedly forked. Colorado to California and southward. 



2. P. occidentalis (A. Nelson) Rydberg. Rootstock short 

 and thick, densely covered with rusty hair-like scales ; stipes 

 cespitose, ^ — i^' long, dark brown, glabrous, shining, very 

 slender; fronds i^' — 3^' long, oblong, simply pinnate; pinnae 

 2 — 5 pairs, oblong, mostly obtuse, dark green, shining, firm and 

 somewhat coriaceous, entire or the lower ones with one or two 

 lobes at the base ; indusium broad, wholly covering the sori. 

 {Pellaa putnila Rydberg, P. atropurfurea occidentalis A. 

 Nelson.) South Dakota to Montana and Washington. 



§ 2. Allosorus Baker. Texture coriaceous, the veins not 

 perceptible ; indusium broad, conspicuous. 



* Pinnules or segments obtuse or barely acute. 

 t Fronds pinnate or bipinnate. 



3. P. atropurpurea (L.) Link. Stipes tufted, 2' — 6' long, 

 dark-purple; fronds 4' — 12' long, 2' — 5' broad, lanceolate or 

 ovate-lanceolate, simply pinnate or bipinnate below ; pinnules 

 and upper pinnae i' — 2' long, J' broad or less, nearly sessile, 

 smooth; indusium formed of the slightly altered incurved edge 

 of the pinnules. {^Allosorus atropurpureus Kunze, Pteris atro- 

 purpurea L., Platyloma atropurpurea J. Sm.) Arizona, New 

 Mexico, Texas to Vermont and northward. 



4. P. aspera (Hook.) Baker. Stipes slender, 2' — 3' long, 

 with scurfy pubescence , fronds 4' — 6' long, oblong-lanceolate^ 

 bipinnate ; pinnae and pinnules deltoid-lanceolate or oblong, 

 pinnules next to main rachis often lobed ; all of them rough on 

 both surfaces with short harsh hairs. {Ckeilanthes aspera Hook.) 

 Western Texas and New Mexico. 



tt Fronds bi — quadripinnate, ultimate segments oval or cordate. 



5. P. andromedsefolia (Kaulf.) Fee. Stipes scattered, pale- 

 brown, 2' — 12' long; fronds 6' — 12' long, 3' — 6' broad, ovate, 

 bi — quadripinnate, usually tripinnate ; pinnae rather distant, 

 spreading ; ultimate pinnules 2" — 5" long, oval, slightly cordate, 



