•12 Polypodiaceae Osmunda 



3b. Osmunda cinnamomea f. fronddsa (T. & G.) Britt. (Cat. Plants of 

 New Jersey, p. 312. 1890.) This form has the fertile frond partly leafy, 

 the fertile and sterile pinnae variously intermixed. I found this unusual 

 form in Lagrange County and Nieuwland found it in St. Joseph County. 



3c. Osmunda cinnamomea f. incisa (Huntington) Gilbert. (List North 

 American Ptericlophytes, pp. 13, 28. 1901.) This form usually has acutely 

 toothed or lobed segments. I found it in De Kalb County. 



3. POLYPODIACEAE R. Br. Fern Family 



Fronds conspicuously dimorphic, the fertile ones with divisions greatly contracted or 

 berrylike, brown when fully mature. 

 Sterile fronds pinnatifid, the veins netted; fertile fronds bipinnate, the divisions 



berrylike 4. Onoclea, p. 45. 



Sterile fronds bipinnatifid, the veins free; fertile fronds pinnate, the divisions linear, 



strongly ascending 3. Pteretis, p. 44. 



Fronds not conspicuously dimorphic, all green. 



Sori marginal, the indusium appearing to consist of the reflexed margin of the seg- 

 ments of the frond or of a marginal cup. 

 Fronds with sporangia borne in minute cuplike indusia near the notches of the 

 segments, the sori separate; fronds bipinnate, the lower surface well covered 



with short, erect, glandular hairs 7. Dennstaedtia, p. 50. 



Fronds not as above. 



Stipes stout (2-4 mm in diameter), commonly solitary, green (stramineous or 



pale brown in dried specimens) 15. Pteridum, p. 57. 



Stipes less than 2 mm in diameter, commonly clustered (brown to blackish). 

 Pinnules pubescent above and below with long, white hairs, densely so along 



the margins below , 13. Cheilanthes, p. 56. 



Pinnules glabrous or with a few scattered hairs. 



Indusia of pinnules continuous; fronds coriaceous, pinnate or bipinnate. 



12. Pellaea, p. 55. 



Indusia definitely interrupted on the fanlike margin of the pinnule; fronds 

 delicate, branched at the summit, the branches definitely pinnate. 



14. Adiantum, p. 57. 



Sori dorsal, not marginal (except in Dryopteris marginalis) . 



Sori and indusia (when present) more or less circular, or reniform. 



Fronds pinnate, pinnules narrowly oblong-lanceolate with an auricle at the 

 base of the upper margin, the stipe and rachis thickly covered with scales ; 

 pinnules of fertile fronds contracted; sori confluent. .6. Polystichum, p. 50. 

 Fronds not as above. 



Stipe, rachis, and lower surface of the pinnae more or less glandular-puberu- 



lent; stipe and rachis deciduously chaffy 1. Woodsia, p. 43. 



Stipe, rachis, and lower surface of pinnae not, or not all, more or less glandu- 

 lar-puberulent. 

 Fronds deeply pinnatifid, the divisions confluent at the base; sori naked; 



blades of fronds coriaceous 16. Polypodium, p. 57. 



Fronds not as above. 



Indusia attached in the center or lacking, if lacking then the rachis 



pubescent and chaffy 5. Dryopteris, p. 45. 



Indusia attached by a broad base on the side toward the midrib and partly 

 under the sori, opening on the opposite side. . .2. Cystopteris, p. 43. 

 Sori elongated, oblong to linear, often curved. 



Sori in rows parallel to the midribs of the pinnae and along the midveins of the 



segments 11. Woodwardia, p. 55. 



Sori not disposed as above. 



