FERNS OF THE DisTRICT OF COLUMBIA 43 
stricted localities in the Coastal Plain, and probably 
of commoner occurrence. Occasionally offered for sale 
in Washington markets, where it is known as ‘ Alice’s 
fern.” 
POLY PODIACEAE 
Potypopium potypopiomeEs (L.) Warr. Shaded, 
flat, mossy rocks; gorge of the Potomac below Great 
Falls, Maryland side, the only locality. This species 
is here near its northern limit. 
PoLypopiIuM VULGARE L. Rocky banks or partially 
shaded cliffs; common along the upper Potomac and 
found in a few other localities. 
ADIANTUM PEDATUM L. Rich, well-drained, rocky 
deciduous woods and shaded hillsides; common. 
CHEILANTHES LANOSA (Micux.) Watt. Earthy crev- 
ices of cliffs or rocky bluffs of the upper Potomac; rare; 
only three stations known, two of these near Great 
alls 
PELLAEA ATROPURPUREA. (L.) Linx. Several scat- 
tered stations; abundant at only one (Georgetown), 
here growing profusely in the mortar of an old retaining 
wall 
PTERIDIUM LATIUSCULUM (Desy.) Maxon.® Sunny, 
sandy slopes, low thin woods, or old fields, and acid 
soil situations generally; abundant. (Pteridium aqui- 
linum of American authors, in part.) 
’ Pteridium latiusculum yeni as Maxon. 
Pteris cacereaee Desy. Mém. Soc. oe 6: 303. 
This appears be the proper n ae ie common pols of ro 
eastern United hots which di Paes very denaitedy from the Euro 
P. aquilinum (L.) Kuhn in Sao and cut of blade and in its elattene or 
quite nonciliate outer indusium, P. aqui ana having the outer indusi 
conspicuously and i "Jong-ciliate. esvaux’s brief description 
i hacichatecy: A photograph of the type specimen (in the Paris Her- 
ona- - 
und! erre. 
foundland material at hand agrees with the fronds shown in the photo- 
