Fronds of Dryopteris carthusiana range from 15-75 cm in
length, and most healthy plants in our area are at least 40 cm
long. The blades are clearly longer than wide, 2 pinnate-pinnatifid
or further divided. Tan scales are conspicuous at least at the
base of the stipe.
Dryopteris carthusiana and D. intermedia are similar
in general appearance and both are common. For D. carthusiana
the lower basal pinnule
of the lowest pinna is longer than the adjacent pinnules,
and it is shorter than the adjacent pinnules in D. intermedia.
Some fronds are difficult to place on this basis and it is wise
to look at a large sample of leaves if there is any question.
Fronds of D. intermedia are evergreen and those of D.
carthusiana are not, a character that is very helpful in winter
and spring. Glands on the indusia and midribs of blade segments
of D. intermedia are a good character, but they can be
difficult to see, tend to wear off as the fronds age and generally
require a good hand lens or dissecting scope for observation.
There are no glands on D. carthusiana.
D. expansa, a very rare species in Wisconsin, is similar
to D. carthusiana, but the lower basal pinnules of the
lowest pinnae of D. expansa are very large relative
to the upper basal pinnules. See the key to Dryopteris
species or the Flora of North America for more information.
D. carthusiana ranges across Canada and throughout the
northeastern U.S., south to South Carolina and Arkansas and west
to Nebraska and North Dakota. It is also known in the northwest
from Montana to Washington. It is found throughout Wisconsin.
Habitats include moist forests and swamps.