Intermediate Wood Fern

Appearance

"Dryopteris intermedia" is a perennial fern that grows to a size of about 40–90 cm tall and 60–90 cm wide. At its base, it consists of an underground rhizome from which grow the fronds of the plant in a spiral-like arrangement.

Each frond consists of a stipe that is covered in light-brown scales towards the base and short glandular hairs further up. The stipes generally measure between 1/4 to 1/3 the length of the frond and support a leaf blade that is lance-oblong in shape.

The leaves themselves are bipinnately compound, meaning that they divide into leaflets called "pinnae" and sub-leaflets called "pinnules". The pinnules of this species are lobed and toothed. Uniquely, the first pinnule closest to the stem on the lowest pinna is shorter than the second.

Naming

Other common names for this species include intermediate shield fern, fancy wood fern, fancy fern, glandular wood fern, American shield fern and common wood fern.

This fern is often confused with several other wood fern species, including "D. carthusiana", "D. campyloptera", and "D. expansa". It especially extensively shares the range of "D. carthusiana", but the two may be distinguished by the innermost pinnule on the bottom side of the bottom pinna: this pinnule is longer than the adjacent pinnules in "D. carthusiana", but shorter or even in "D. intermedia".

Distribution

"Dryopteris intermedia" is native to most of eastern North America, ranging from Minnesota in the north-west and Newfoundland and Labrador in the north-east, down to Alabama in the south-west and South Carolina in the south-east. While globally secure, it is considered by NatureServe to be "critically imperiled" in the states of Iowa and Missouri which represent the western limit of its range, and "imperiled" in the states of Illinois and South Carolina as well as the region of Labrador.

Habitat

"Dryopteris intermedia" grows in a variety of mesic habitats including forests, woodlands, ravines, swamp edges and rocky slopes.