North of Lake Superior occur two additional species of Woodsia which one day may be discovered in Michigan. Woodsia glabella differs from all our species in being essentially hairless. With its greenish to pale brown petioles, it looks more like an Asplenium than a Woodsia, differing, however, in its round sori. Woodsia scopulina has petioles lacking a joint, but differs from our two species with which it shares this feature by having conspicuous multicellular hairs along the midrib on both surfaces of the pinnae.
Small Cystopteris species growing on rock are often mistaken for Woodsia. In addition to being less hairy and scaly, Cystopteris lack the persistent petiole bases so characteristic of our Woodsia species.
1. Petioles jointed (visible as a small thickening) near the base at about the same height on all the plants so that the persistent bases remaining after the leaf has been shed forms a “brush” of old stalks; rachis without glandular hairs.
2. Rachis with abundant brownish hairs and scales; undersides of pinnae with abundant brownish scales.
2. Rachis with at most widely scattered hairs and scales, often essentially glabrous; undersides of pinnae essentially lacking scales.
1. Petioles not jointed, the leaves thus shedding irregularly leaving persistent bases of varying lengths; delicate glandular hairs present (sometimes sparse) on rachis.
3. Broad based multicellular scales conspicuous on petioles and extending into the rachis of the blade.
3. Broad based multicellular scales sparse on the lower portions of the petioles and absent on the rachis.
All species found in Woodsia
MICHIGAN FLORA ONLINE. A. A. Reznicek, E. G. Voss, & B. S. Walters. February 2011. University of Michigan. Web. July 25, 2017. http://michiganflora.net/genus.aspx?id=Woodsia.