Jones: Flora of Illinois, 8. Polypodiaceae 35 



4. Sori dorsal. 



5. Indusium wholly inferior, roundish at first, soon splitting 4. Woodsia 



5. Indusium partly inferior, delicate, hood-like, attached by its base at one side 

 5. C^stopleris 



3. Indusium superior or none. 



6. Sori dorsal, i.e., on the back of the leaves away from the margin, or if apparently 

 near the margin not covered by the revolute edge of the leaf-segments. 



7. Sori orbicular or nearly so. 



8. Indusium peltate or reniform, conspicuous, but often soon deciduous. 



9. Indusium peltate; leaves (in our species) 1 -pinnate, the stipe and rachis 

 scaly, the pinnules spinulose-serrate, auriculate at the base of the 

 upper side 6. Polyslichum 



9. Indusium reniform, attached at its sinus; leaves 1 -3-pinnately compound 



7. Dr^opleris 



8. Indusium none. 



10. Leaves 2-3-pinnatifid, not jointed to the rhizome; sori small, on the backs 



of the veins 8. Phegopieris 



10. Leaves pinnately lobed, jointed to and arising from roundish knobs on 



the chaffy rhizome; sori large 9. Pol\)podium 



7. Sori elongated, oval to oblong or linear, straight or curved, two or more times 



as long as wide. 



11. Leaves simple, entire, 5-30 cm. long, lanceolate, tapering from a truncate 



or cordate or even hastate base, rooting at the tip and thus giving rise to 



new plants; veins forking and anastomosing 10. Campiosorus 



1 1. Leaves pinnate or pinnatifld. 



12. Leaves evergreen, coriaceous, small (5-40 cm. long); petioles firm, 



slender, wiry, brown or black ]\. Asplemum 



12. Leaves not evergreen, herbaceous; petioles soft, stoutish, stramineous 

 (when dry). 

 13. Son in chain-like rows parallel to the midveins; veins united to 

 form a series of narrow areolae along the midrib, elsewhere free 



14. IVoodwardia 



13. Sori and venation otherwise. 



14. Pinnae pinnate, the segments coarsely and irregularly toothed or 



incised 12. Alhy^rium 



14. Pinnae pinnatifid or merely undulate, or entire 13. Diplazium 



6. Sori marginal, i.e., borne at the edges of the lobes or segments of the leaves, 

 either in definite sori or in a continuous line and covered by the revolute leaf- 

 margin. 

 1 5. Leaves pedate, the petioles forked at the summit, dark brown or black, smooth, 



glossy; pinnules flabellate; sori several, distinct 17. Adianium 



15. Leaves pinnate, the petioles simple; sori apparently continuous along the 

 margin of the pinnule. 

 16. Petioles slender, less than 2 mm. thick; leaves small, ovate-lanceolate; 

 rhizome erect, or short-horizontal, copiously scaly. 

 17. Leaves glabrous. 



18. Leaves dimorphous, delicate, membranous; pinnules of the sterile 



leaves cuneate at the sessile or nearly sessile base 



1 4. Cr^plogramma 



18. Leaves uniform or nearly so, coriaceous; pinnules short-petiolulate 



at the rounded or truncate base 15. Pellaea 



17. Leaves pubescent, uniform; pinnules cuneate at the sessile or nearly 



sessile base 18. Cnetlanlnes 



16. Petioles coarse, 2-10 mm. thick; leaves large, coarse, triangular, 1-3-pin- 



nate, 30-100 cm. long; rhizomes horizontal, black, not scaly 



19. Pteridium 



