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, Pteris 

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

 Illinois, Colorado, and northward. 



2. ALLOSORUS Baker. Texture coriaceous, the veins not 

 perceptible ; indusium broad, conspictwus. 



* Pinnules or segments obtuse or barely acute. 

 t Fronds pinnate or bipinnate. 



3. P. atropurpurea 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, ' broad or less, nearly sessile, smooth ; 

 indusium formed of the slightly altered incurved edge of the 

 pinnules. (Allosorus atropiirpureus Kunze, Pteris atropurpurea 

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

 Texas to Vermont and northward. 



4. P. aspera Baker. Stipes slender, 2' 3' long, black 

 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. 



tt Fronds bi quadripinnate, ultimate segments oval or cordate. 



5. P. andromedaefolia Fee. Stipes scattered, erect, 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 andromedccfolia Kaulf.) California. 



6. P. pulchella Fee. Stipes densely tufted, 3' 8' long, 

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

 triangular-ovate, quadripinnate below, gradually simpler above ; 

 lower pinnse deltoid, narrowly triangular above; ultimate pin- 

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

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



