4 POLYPODIACEAE 



5. DRYOPTERIS Adaus. 



Differs from the last genus chiefly in liaving the cordate-reniform or 

 orbicular indnsinni fixed by the sinus. 



1. D. Thelypteris (L. ) A. Gray. Bog Fern. Rootstocks slender, 

 long, creeping, black : stipe smooth, 9'-20'' high : frond 9^-12' long, 

 pinnate and slightly downy : pinnae 1^-2^ long, long-lanceolate in out- 

 line, pinnatilid into oblong lobes, each pinna bearing from 10-18 sori : 

 veinlets forking : indusium reniform.- — In a bog along the foot of the 

 bluffs about two miles west of Sibley. July-August. 



6. CAMPTOSORUS Link. 



Low spreading ferns with undulate-margined fronds and linear sori 

 which are irregularly scattered on either side of the reticulated veinlets. 

 Indusium fixed lengthwise to the veinlet. 



1. C. rhizophyllus (L. ) Link. Walking Fern. Fronds ever- 

 green, thick, cordate at base, gradually narrowing into a long, slender 

 tip, which takes root and forms a new plant : sori numerous. — In dense 

 patches on moss-covered rocks in shady woods throughout, but nowhere 

 common. June-October. 



7. ATHYRIUM Roth. 

 Fronds twice pinnate with oblong or linear sori oblique to the mid vein. 

 Indusia curved, fixed lengthwise to inner side of vein. 



1. A. Filix foemina (L. ) Roth. Lady Fern. Fronds numerous, 

 from a rather stout rootstock, 8'-30' long, oblong-lanceolate with about 

 twenty pairs of long-lanceolate pinnae: pinnae once pinnatifid, the seg- 

 ments incised. — A handsome symmetriciil fern, locally common in sandy 

 woods west of Sibley. June-August. 



8. ASPLENIUM L. 

 Fronds once pinnate. Sori linear or oblong, oblique to the midvein. 

 Indusia straight, fixed lengthwise to inner side of vein. 



Pinnae entire : l°-4° high. 1. A. aiujitslifoliiDn. 

 Pinnae variously incised : low ferns. 



Sori few, not crowded. 2. A. parritlum. 



Sori numerous, crowded. 3. A. platyneuron. 



1 A. angustifolium Michx. Tall Spleenwokt. 2°-4° high : 

 pinnae 20—10 pairs, long-lanceolate, acuminate : sori crowded, covering 

 the lower surface of the pinnae. — Frequent in rich woods along the Mis- 

 souri River bluiTs, especially west of .Sihiey. August-Septemher. 



2. A. parvulum .Mart. & Gal. Small Spleicnwokt. Stipes tufted, 

 black, short : fronds ohlong-Iinear, 4^-12^ long : pinnae 3''-.5" long, 

 oblong, crennlate, anricled on the upper side : fruit dots one to seven 

 pairs on each pinna, midway between the midvein and the margin. — A 

 few plants were found in 1884 in a thicket on the bluffs near Courtney. 

 The station has since been destroyed. June-October. 



