Woodsia ilvensis is a small fern that usually grows on
rocks. The fronds are less than 25 cm long and 3.5 cm wide and
grow in clumps. The blade is usually twice pinnate, at least at
the base, and the abaxial (lower)
surface bears conspicuous hairs and scales. The veins end
short of the margin in a raised "hydathode",
best seen on the adaxial (upper) surface of the segments. The
stipe (sometimes referred to as "jointed") breaks off
at an abcission layer,
leaving a conspicuous persistent
base that is useful in distinguishing this species.
W. ilvensis is known from Newfoundland and the farthest
northern portions of Quebec and Yukon to Virginia, Ohio and Minnesota.
It is also found in the west from Alaska to British Columbia and
Alberta. It is widely distributed in Wisconsin, but absent in
the eastern counties and in the mid-northern region. Even in the
areas for which it is known it is often very local.