Hairy stem of the rare Pellaea atropurpurea. Photo by Matt Zine, Wisconsin DNR.

Phenology spotlight: purple-stem cliff-brake

October 6, 2015

Despite the cold temps and snowpack, winter can be a great time to botanize. Of course trees can be identified year round, but there are other targets as well. Evergreen ferns and fern allies are one example of plants that can be seen in the winter, and one that I am always on the lookout for is purple-stem cliff brake (Pellaea atropurpurea). This evergreen, rock-loving fern is found across North America but is relatively disjunct in the Badger State, where populations are restricted to the Driftless Area. The key to identifying this smallish species, listed as Special Concern in WI, is the hairy stems. It much more common relative, Pellaea glabella, lacks this pubescence although the overall size and habitat preference are similar. You may want to have your hand lens with you when you set out botanizing for Pellaeas. The hairy stems are often apparent to the naked eye, but some magnification can be helpful to confirm your suspicions. So if you’re hiking through a bluff prairie and find a sandstone outcrop take a second to scan the open rock face for the slender, unlobed pinnaea of one of Wisconsin’s rarest ferns.

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