36 American Midland Naturalist Monograph No. 2 



1. Onoclea L. 



O. sensibilis L. Sensitive Fern. Moist woods, or edges of meadows, 

 common. 



2. Pteretis Raf. 



P. nodulosa (Michx.) Nieuwl. Ostrich Fern. Wet ground, not common; 

 n. III., southwd. to Peoria Co. [Onoclea nodulosa Michx.; Matteuccia struthi- 

 opteris and Onoclea struthiopteris of Am. auth.} 



3. Cystopteris Bernh. — Bladder Fern 



i. Leaves narrowly lanceolate, 30-120 cm. long when mature; axils of some of 

 the upper pinnae usually bearing small bulblets on the lower surface; basal 



pair of pinnae the largest; on moist cliffs in shaded ravines 



" C. bulbijera (L.) Bernh. 



1. Leaves broadly lanceolate, acute, 20-40 cm. long, the basal pair of pinnae 



usually slightly shortened; bulblets none; moist soil in woods, common 



C. f'^agilis (L.) Bernh. 



4. WooDsiA R. Br. 



L Leaves 20-50 cm. long, minutely glandular; petiole not jointed; indusium 

 ample, with few broad spreading jagged lobes; cliffs, not common. Cliff 

 Fern W. obtusa (Spreng.) Torr. 



I. Leaves 5-15 cm. long, rusty-chaffy beneath; petiole jointed a short distance 

 above its base; indusium inconspicuous, the divisions filiform; cliffs, rare. 

 Ogle Co. Rock Woodsia W. ilvensis (L.) R. Br. 



5. Dennstaedtia Bernh. 



{Diclfsonia L'Her.) 



D. punctilobtila (Michx.) Moore. Hay-scented Fern. Sandstone cliffs in 

 wooded ravines, rare. Wabash Co., Schneck. 



6. POLYSTICHUM Roth 



P. acrostichoides (Michx.) Schott. Christmas Fern. Common in wooded 

 ravines. 



7. Dryopteris Adans. 



(^Aspidium Sw. ; Thelyipteris Schmidel) 



1. Leaves membranous, not evergreen; vascular bundles of the petiole 2, free 

 or united; rhizomes slender, almost without scales. 



2. Lowest pinnae reduced in length, widely spaced, deffexed, the blade there- 

 fore conspicuously narrowed at the base; margins of the pinnules flat; 

 indusium glandular; veins mostly simple; vascular bundles usually 



united; woods and thickets, rare. New York Fern 



D. noveboracensis (L.) Gray 



2. Lowest pinnae only slightly reduced; margins of the pinnules revolute; 

 indusium glandless; veins forked; vascular bundles 2, distinct; marshes, 

 common. Marsh Fern D. thclypteris (L.) Gra) 



