Rock Clubmoss Huperzia porophila (Lloyd & Underwood) HolubExtirpated  Synonyms: Lycopodium porophilum.


Rock Clubmoss is extirpated from Maryland. There was only one known population that was located along the Youghiogheny River in Garrett County. The last time the population was observed was back in 1982 along a wet outcrop by a waterfall (MD Heritage Program, 2018). Rock Clubmoss is most often found on the western edge of the of the central Appalachian Mountains with only scattered populations on the eastern edge of the Appalachians. Rock Clubmoss, according to Weakley's Flora of the Southeast is found on, "Rock outcrops and cliffs, especially in the spray of waterfalls, at low to medium elevations."


Rock Clubmoss is very similar to Shining Clubmoss (Huperzia lucidula) and care must be taken when trying to identify the two species. In Maryland, Rock Clubmoss would only be found in Garrett County. Any Huperzia found off the Allegheny Plateau in Maryland is almost certainly Shining Clubmoss. The habitat of the two Huperzia species are also different. As noted above, Rock Clubmoss is found growing on rocky substrates usually near waterfalls while Shining Clubmoss can be found in a number of different habitats including hardwood forests and wooded swamps. The leaves of the two species are also different (a 10x hand lens is needed to really get a good look at the leaves). Rock Clubmoss has leaves that are oblanceolate (lanceolate with a blunt round tip) and Shining Clubmoss has leaves that are lanceolate. Shining Clubmoss has noticeable serrations on the edge of the leaves while Rock Clubmoss has leaf edges with few serrations that are much less defined (Weakley, 2015).

There are 2 records in the project database.

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Rock Clubmoss in Rabun Co., Georgia (5/27/2012). Unfortunately, Rock Clubmoss is extirpated in Maryland. Photo by Jim Fowler. (MBP list)

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