Spiny wood fern (Dryopteris expansa), is one of our woodland plants that has continued to look good through the dry days of August while some of the other perennials have gone into summer dormancy or looked tired and droopy. We have quite a lot of wood fern growing in our woods, almost always on decaying conifer logs or stumps.
This deciduous fern is easy to recognize, although with just a quick glance you could confuse it with lady fern or male fern. Spiny wood fern has fronds that are broader at the base than at the tip, with a triangular shape that tapers to a point. It gets the spiny part of its name from the chaffy brown scales along the lower part of the leaf stems.
The fronds are clustered, erect and spreading from the base. Each frond (leaf) is pinnately divided three times, with 5-20 pairs of leaflets and the lowest pair broadly triangular and asymmetrical. Lady fern, also deciduous, has fronds that taper at both the tip and the base.
Spiny wood fern is native to the Pacific Northwest from Alaska to California, as well as portions of the Rocky Mountain states and eastern Canada.
It grows mostly in shady conditions in the woods, preferring moist organic soil that is somewhat acidic. You’ll want to give it similar conditions in the woodland garden, where it will form nice clumps without becoming invasive. You can get it established from spores or from nursery plants.