50 WOODSIA OBTUSA.—COMMON WOODSIA. 
tration grew, these barren fronds keep tolerably green till the 
new ones come in spring, when they give way soon after the 
appearance of the fertile fronds, and, later in the season, another 
set of barren fronds appear. Our specimen was taken about 
the end of May, and from this time to the end of October the 
student may find along the Wissahickon excellent specimens for 
study. In other parts of the country the plant does not seem to 
be so highly favored. Mr. Williamson says, in his “Ferns of 
Kentucky,” “that in that State it grows in exposed situations, 
being better able to endure the direct rays of the sun than most 
ferns. But in such places the pinnze are often very much 
contracted, so that they seem to be crisp, and apparently rolled 
up.” In Indiana also, according to a correspondent of the first 
volume of the “ Botanical Gazette,’ who writes from Hanover, it 
dies away early in the season. He says: “Early in July, while 
rambling among some of the limestone cliff rocks of the Ohio 
River, we secured our first specimens of Asplendum Rita-mura- 
za, in beautiful fruit; and since then we have visited the same 
region every month in order to confirm our observations as to its 
being an evergreen, and we are now fully convinced of the accu- 
racy of our former remarks on this point. Associated with this 
species and fruiting abundantly at the same time, we found quite 
a growth of Iloodsta ob/usa, but by the end of August it had 
entirely withered away. Its fruiting season begins here proba- 
bly early in June.” Other botanists seem to have very much lim- 
ited the time when it may be found in fruit. Dr. Darlington in 
his “Flora Cestrica”’ gives merely “ July ;” as also does Professor 
Asa Gray and Professor Wood, from whom our botanical 
description is taken. They are probably referring to the time of 
the fruit’s first appearance; but for the benefit of those who are 
making collections it is well to note how long it endures. 
Its botanical history has been varied. The knowledge of the 
true character of ferns is of comparatively modern date. In the 
time of Linnzus all the known North American ferns would be 
referred to a very few genera, possibly only to Osmunda, Plerts, 
