8. POLYPODIACEAE 43 



2. Sterile and fertile leaves similar, the latter bearing 2-6 pairs of 

 fertile pinnae near the middle: pinnae of the sterile leaves 

 lacking tufts of tomentum at base; moist ground in woods, 

 local. Interrupted Fern O. claytoniana L. 



8. Polypodiaceae S.F.Gray — Fern Family 



1. Sporangia enclosed in globose or necklace-like brownish portions of the 

 contracted and modified fertile leaves; fertile and sterile leaves dissimilar. 

 2. Sterile leaves 1-pinnatifid. the veins reticulate; fertile leaves 2-pinnate; 

 rhizome horizontal, the leaves therefore solitary 1. Onoclea 



2. Sterile leaves 2-pinnatifid, the veins free; fertile leaves 1-pinnate; 



rhizome short, erect, the leaves therefore tufted 2. Matteuccia 



1. Sporangia on the margin or back of ordinary foliar or modified leaves. 



3. Indusium inferior or partly so (often evanescent). 

 4. Sori dorsal. 



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



at one side 3. Cystopteris 



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

 4. Sori marginal, in minute cup-like inferior indusia at the ends of the 

 veins; leaves bipinnate, delicate, fragrant, sparsely glandular- 

 pubescent 5. Dennstaedtia 



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 co\ered by the revolute edge of 

 the leaf-segments. 

 7. Sori roundish. 



8. Stipes not jointed to the rhizome; indusium (if present) con- 

 spicuous, but often soon deciduous. 

 9. Indusium orbicular, peltate; leaves (in our species) 1-pinnate, 

 the stipe and rachis scaly, the pinnules spinulose-serrate, 



auriculate at the base of the upper margin 6. Polystichum 



9. Indusium (lacking in some species) reniform, attached at its 



sinus; leaves 1-3-pinnately compound 7. Dryopteris 



8. Stipes jointed to the rhizome; blades pinnately lobed; indusium 



none 8. Poly podium 



1 . Sori elongated, oval to oblong or linear, straight or cur\ed, two or 



more times as long as wide. 



10. 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 9. Camptosorus 



10. Leaves pinnate or pinnatifid. 



11. Leaves evergreen, coriaceous, small (5-40 cm long); stipes 



firm, slender, wiry, brown or black 10. Asplenium 



11. Leaves not evergreen, herbaceous; stipes soft, stoutish, 

 stramineous (when dry). 

 12. Sori in chain-like rows parallel to the midveins; veins 

 united to form a series of narrow areolae along the 



midrib, elsewhere free 12. Woodwardia 



12. Sori and venation otherwise 11. Athyrium 



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

 leaves, either in definite sori or in a conspicuous line and covered 

 bv the revolute leaf-margin. 



