V V 13 
146. D. spinulosa di!atata Hoffm. This is a more highly- 
developed form of the typical plant, the lower pinnae at times be- 
ing very broad and fronds often tripinnate ; indusiiim smooth. At- 
tains its best development in the northern sections. June. Europe. 
V 
147. D. Boottii (Tuck.) Underw. Fronds 1-2 J feet long 
Laminae ovate-lanceolate, bipinnate ; upper pinnae lanceolate, the 
lower triangular, both with crenate, spinulose teeth. Sori in rows 
each side of the midvein, one to each tooth or scattering on the 
pinnules next the rachis, indusium large, minutely glandular. 
Variable. Frequent in shaded swamps, apparently most so in 
eastern sections. North American. July. 
CYSTOPTERIS Bernh Bladder Fern. 
Sori dorsal, roundish ; indusia hood-shaped, fixed by a broad base, 
opening towards front side and soon thrown off. 
1 5 1 . C. bulbifera (L.) Bernh. Bulbous Bladder fern. Fronds 
long lanceolate, 1-2 feet, bipinnate ; pinnae lanceolate-oblong, low- 
ermost pair longest ; pinnules crowded, bearing bulblets beneath ; 
indusium obtuse on the free end ; stipe short ; rachis wingless. 
Shaded ravines in calcareous districts. Mt Toby, Mass. ; Guilford, 
Conn. ; Mt Willoughby, Vt. West of the Connecticut river, and in 
Northern N. H. and Northern Me. North America, east of Arkan- 
sas and north of Tennesee Late in July. 
t 152. C. fragilis (L.) Bernh. Fragile Bladder Fern. Fronds 
5-12 inches long ; laminae lance-oblong, bi-tripinnate ; stipe longer 
than in the preceding species and very brittle ; rachis winged ; in- 
dusium acute on front side. Very variable. Damp shaded places, 
usually disappearing in August. Common, but easily overlooked. 
Early July. One of the most universally distributed ferns ; found 
from Arctic regions to the southern extremities of the continent, 
and in New Zealand. 
ONOCLEA L. 
Sori enclosed in the revolute segments of the contracted fertile 
frond. Sterile fronds very different from the fertile. 
