98 OUR NATIVE FERNS AND THEIR ALLIES. 



rachis into a few broad, blunt, slightly-lobed pinnules; texture 

 thinly herbaceous, flaccid ; indusium broad, continuous, mem- 

 branous ; veins of the fertile fronds mostly only once forked. 

 {Allosorus crispus, var. Stelleri Milde, A. gracilis Presl, Pier is 

 gracilis Michx., P. Stelleri Gmelin.) Labrador to Pennsylvania, 

 Illinois, Colorado, and northward. 



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 pinnse 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. (Cheilanthes aspera Hook.) 

 Western Texas and New Mexico. 



ft Fronds bi quadripinnate, ultimate segments oval or cordate. 



5. P. andromedaefolia (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, 

 coriaceous, the margin of the fertile ones sometimes revolute to 

 the midrib; veins numerous, parallel. {Allosorus andromedce- 

 folius Kaulf., Pteris andromed&folia Kaulf.) California. 



6. P. pulchella (M. et G.) Fee. Stipes tufted, 3' 8' long, 

 chaffy at base, nearly black; fronds 3' 9' long, i' 5' broad, 

 triangular-ovate, quadripinnate below, gradually simpler above ; 

 lower pinnae deltoid, narrowly triangular above; ultimate pin- 

 nules numerous, i" 3" long, oval or often cordate-ovate, 

 stalked, coriaceous, smooth, the edges often much reflexed. 



