8. Poly FODi ACE AE 45 



6. Polystichum Roth — Christmas Fern 

 P. acrostic hoides (Michx.) Schott. In wooded ravines, conmioii. 



7. Dryopteris Adans. 

 1. Indusiuni none; leaves triangular; rhizome slender, horizontal. 

 2. Leaves ternate, glabrous, the three divisions stalked ; rachis not 

 winged; wooded ravines, rare; Ogle and St. Clair counties. 



Oak Fern [Phegopteris dryopteris (L.) Fee] 



D. disjuncta (Ledeb.) Morton 



2. Leaves twice pinnatifid, pubescent or glandular beneath, the 

 pinnae all sessile, adnate to the rachis. 



3. Rachis terete and wingless above the lowest pair of pinnae; 



moist ravines, cliffs, and woods, rare; Henderson, La Salle, 



Menard, Ogle and Pulaski counties. Long Beech Fern 



D. phegopteris (L.) C.Chr. 



3. Rachis winged above the lowest pair of pinnae by their 



adnate bases; rich woods and ravines, not uncommon. 



Broad Beech Fern D. hexagonoptera (Michx.) C.Chr. 



1. Indusium present. 



4. Leaves membranous, not evergreen ; vascular bundles of the 



stipe two, free or united ; rhizomes slender, almost without 



scales. 



5. Lowest pinnae reduced in length, widely spaced, deflexed, the 



blade therefore conspicuously narrowed toward the base; 



margins of the pinnules flat; indusium glandular; veins 



mostly simple; woods and thickets, rare. New York Fern 



D. noveboracensis (L.) A.Gray 



5. Lowest pinnae only slightly reduced; margins of the pinnules 



revolute; indusium ciliate; veins of the sterile blades 

 forked; marshes, common, except in the southern counties. 



Marsh Fern D. thelypteris (L.) A.Gray 



4. Leaves of firm texture, often evergreen; vascular bundles of the 

 stipe five or more; rhizome stout, conspicuously scaly. 



6. Leaves 1 -pinnate, or rarely 2-pinnate. 



7. Sori on the margin of the obscurely crenate or entire pin- 

 nules; leaves coriaceous; sandstone clifTs and wooded 



ravines, not uncommon. Marginal Wood Fern 



D. marginalis (L.) A.Gray 



7. Sori near the midvein; pinnules toothed. 



8. Leaf-blades 20-40 cm wide, ovate in outline, scarcely 

 narrowed below; pinnae broadest near the middle; 

 rich woods in ravines, rare; known from Fulton, 

 Gnmdy, La Salle, McLean, Peoria, and \Vill counties. 



Goldie's Fern D. goldiana (Hook.) A.Gray 



8. Leaf-blades narrower, elliptical in outline, narrowed at 

 the base; lower pinnae broadest at the base; swampy 



