POLYPODIACEAE 



1. ONOCLEA L. 



Sporanges pedicelled, forming round sori, covered by the membranous 

 indusia, which are attached to the lower side of the sori. Fertile fronds 

 much contracted, the sterile leaf-like. 



1. O. sensibilis L. SENSITIVE FERN. Sterile frond triangular in 

 outline, pinnatifid into lanceolate more or less sinuate-pinnatifid seg- 

 ments: fertile fronds bipinnate: pinnae roundish. Rather rare in swampy 

 woods. Near Independence, Lake City, Courtney and Sibley. August- 

 October. 



2. WOODSIA R. Br. 



Sori borne on the back of the veins. Indusium attached by the base 

 all around the receptacle, early bursting at the top into irregular lobes. 



1. W. obtusa (Spreng.) Torr. CHAFFY FERN. Fronds numerous, 

 4 / -12 / long, lanceolate in outline : pinnae triangular-ovate, pinnately 

 parted with oblong irregularly cut-toothed segments : indusium splitting 

 into 5-7 broad segments acutely jagged at the apex. Frequent through- 

 out the county on rocks. June-August. 



3. FILIX Adans. 



Delicate ferns with pinnate leaves and round sori borne on the back of 

 the veins. Indusium hood-shaped, attached by the base on the inner 

 side, i. e., towards the middle of the frond, soon withering away. 



1. P. fragilis (L. ) Underw. WOOD FERN. Stipe almost glabrous, 

 2 X -8 X long, from a slender rootstock : frond about as long as stipe, broadly 

 lanceolate in outline : pinnae triangular-ovate, irregularly pinnatifid, the 

 pinnules cut-toothed : indusium acute at the free apex. Our most com- 

 mon fern, abundant in rocky woods. Late fruiting plants growing on 

 shaded rocks occasionally develop a few chaffy bulblets in the axils of the 

 pinnae. Such forms have been found at Swope Park, along Brush Creek, 

 and near Courtney. May-September. 



4. POLYSTICHUM Roth. 



Fronds pinnate, bearing round sori on the back of the veins. Indusium 

 flattish, orbicular and peltate, fixed by the center. 



1. P. acrostichoides (Michx.) Schott. CHRISTMAS FERN. Stipes 

 densely chaffy from a stout rootstock : fronds lO'-SO' long, simply pin- 

 nate, the rachis chaffy : pinnae slightly stalked, linear-lanceolate, serru- 

 late with bristly teeth, very oblique at base : sori borne on the upper 

 part of the fertile fronds, confluent : indusium orbicular and peltate, 

 fixed by the depressed center. In rocky woods along the Missouri River 

 bluffs. Not common. July-October. 



