46 AMERICAN FERN JOURNAL 
Dryorreris spinutosa (MveLu.) Kuntze. Rich, 
low woods; common throughout. 
DryopTEeRIs INTERMEDIA (WILLD.) A. Gray. Moist 
or dryish woods; fairly common. 
(The following hybrids besides Dryopteris Boottii have 
been collected: DryopreRis CRISTATA MARGINALIS 
Davenp.; two collections, near Great Falls, Va., Dowell. 
Dryopreris GOLDIANAXMARGINALIS Dowell; woods 
near Kensington, Maryland, Dowell.) 
POLYSTICHUM ACROSTICHOIDES (Micux.) ScHorTt. 
Moist woods and cool, shady banks; abundant through- 
out the range. Easily the most conspicuous fern of 
the region, especially in winter, the thick evergreen 
fronds then closely carpeting the many gullies of Rock 
Creek Park and surrounding country. 
ONocLEA sENsIBILIS L. Moist, open or partially 
shaded, low situations generally; abundant. 
PTERETIS NODULOSA (Micux.) Nrzeuwianp. Shaded, 
alluvial banks (both sides) and islands of the Potomac 
above Cabin John; rare. (Matteuccia Struthiopterts 
and Onoclea Struthiopteris of many American writers.) 
FILix BULBIFERA (L.) Unpprw. Shaded talus of 
cliffs, Virginia side of the Potomac in the region opposite 
Cabin John; very rare. 
Fiurx rracuus (L.) Unperw. Shaded, alluvial flats, 
rocky slopes, and moist woods; abundant in many 
localities, but chiefly along the Potomac. 
Woopsta oprusa (SPRENG.) Torr. Rocky banks and 
partially shaded cliffs; common, especially along the 
upper Potomac and the Canal, usually near water but 
always in well-drained situations. 
DENNSTEDTIA PUNCTILOBULA (Micux.) Moors. Low 
woods and moist, thinly shaded banks; fairly common. 
EQUISETACEAE 
EQUISETUM ARVENSE L. Sandy, often alluvial soil; 
common; several forms. 
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