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, |' 1' 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. 

 (Pellcea piimila Rydberg, P. atropttrpurea 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' 6' 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 cm 

 both surfaces with short harsh hairs. (Cheilanthes aspera Hook.) 

 Western Texas and New Mexico. 



ft Fronds bi quadrip innate, ultimate segments cn>al 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, 



