WOODSIA OBTUSA. 
COMMON WOODSIA. 
NATURAL ORDER, FILICES. 
Woopsia optusa, Torrey.—Frond sub-pinnate, or nearly tri-pinnate. Minutely glandular- 
pilous; leaflets distant; segments of the leaflets pinnatifid; ultimate segments roundish- 
oblong, obtuse, bi-dentate; sori round, one at each cleft between the leaflets, at length 
crowded; stipe somewhat chaffy. Fronds lance-oblong in outline, three times as long 
as wide. Segments of the leaflets crevate-serrate, the lower ones distinct, upper con- 
fluent. Sori orbicular, becoming nearly confluent, each at first enclosed in the silvery 
indusium which when open is notched into little teeth on the margin. (Wood’s Class- 
Book of Botany. See also Gray’s Flora of the Northern United States, Chapman's 
flora of the Southern United States, and Williamson’s Servs of Kentucky.) 
GAGLONG the Wissahickon Creek, in Fairmount Park, Phila- 
ea delphia, and from whence the plant was taken which 
served us for an illustration, this fern is not uncommon, and 
it is remarkable that it is almost always to be found on dry walls 
—that is to say, wails built of stone without mortar—when these 
walls are ina damp or shady place. The little ledges formed by 
the stones, and the little spaces between the stones in the wall, 
are favorite situations with this fern, as also are those parts of 
the stone breastworks of dams over which the water does not 
actually flow. Occasionally it is found in the crevices of rocks, 
but the collector will be much more likely to meet with it in this 
Park by going to the nearest old wall than to any other place. 
It is a very interesting fern, though in all that constitutes 
beauty, there are others superior to it. One of its happiest 
phases is towards the fall of the year, when the short barren 
fronds which form the outer circle bend downwards, forming a 
sort of rosette, in the centre of which the fertile fronds some- 
what erectly stand. In the part of our country where our illus- 
4 (49) 
