102 American Fern Journal 



F. Leaves less than 1 inch wide, linear; leaflets ovate, obtuse 

 or rounded, without lobe at base; petiole slender, shining 

 smooth. 7. Asplenium. 



FF. Leaves normally more than 1 inch wide when mature, 

 linear or lanceolate; leaflets lanceolate to narrowly ovate, 

 acute, with lobe at base on upper side; petiole not slender 

 nor shining, scaly. 5. Polysticbum. 



CC. Leaflets deeply toothed throughout their entire length. 



G. Blade of leaflet not narrowed to its midrib at base except 

 sometimes the lower 1 or 2 pairs; leaf-blade triangular in 

 general form. 3. Phegopteris. 



GG. Blade of leaflet narrowed to its midrib at base. 



H. Leaf-blade obovate or oblanceolate ; lower lobes of the 

 leaflets longer than the others; leaflet-lobes rounded at tip; 

 plant 1-2 feet high. 4. Dryopteris. 



HH. Leaf-blade ovate; lower lobes of the leaflets not longer 

 than the others; leaflet-lobes acute at tip; plant 3-6 feet 

 high. 9. Woodwardia. 



CCC. Lower leaflets lobed at base, ail otherwise entire. 



11. Pellaea. 

 BB. Leaves twice pinnate or pinnately deep-lobed, tufted. 



I. Plants 20 inches or less high. 



J. Leaf-blade triangular in general outline. 



3. Phegopteris. 



JJ. Leaf-blade lanceolate in general outline. 

 K. Plants usually less than 8 inches high. 



L. Petiole coarse; leaflets smooth or covered with fine short 



Inconspicuous white hairs. l. Woodsia. 

 LL. Petiole very slender; leaflets densely covered with brown 

 hairs. 12. Cheilamhes. 



KK. Plants usually 8-20 inches high. 



M. Petiole very slender, hardly scaly at base. 



2. Cystopteris. 

 MM. Petiole coarse, very scaly at base. 5. Polystichum. 



II. Plants over 20 inches high. 



N. Leaflets not contracted to their mid-veins where they join 

 the main leaf-axis, or if so only the lower ones. 



9. Woodwardia. 



NX. Leaflets contracted to their mid-veins where they join the 

 main leaf-axis. 

 O. Leaflets shining beneath; either leaf-blade wide at base 

 or else lower pair of leaflet-lobes conspicuously larger than 

 the others. 4. Dryopteris. 



OO. Leaflets not shining beneath; leaf-blade narrow at base; 

 lower pair of leaflet-lobes not eonspieiiously larger than the 

 others. 6. Athyrium. 



BBB. Leaves thrice pinnate. 



P. Plants less than 1 foot high, densely till rl. 

 Q. Leaves of 2 kinds. 13. Cryptogramma. 



QQ. Leaves all alike. 



R. "Leaf-blades triangular to pentagonal, whitish- or yellowish- 

 powdery beneath. 10. Oeropteris. 



RR. Leaf-blade ovate to lanceolate, not powdery beneath. 



