About Huperzia porophila (F.E.Lloyd & Underw.) Holub
Huperzia porophila, commonly known as rock clubmoss or rock firmoss, grows across the Appalachian province of the Eastern United States and central Canada, ranging from Ontario south to Georgia and Alabama. It is rare east of the Appalachians, and is most common in a north-south belt along the western plateau area. Rock firmoss only grows on or over rock, and requires cool, moist, shaded, acidic locations. It makes a striking appearance when growing over boulders and outcrops. It is frequently confused with shining firmoss (Huperzia lucidula), which largely shares its range and also typically grows on rocks. The leaves of Huperzia porophila measure 3–8 mm long, and are generally not shiny like the leaves of shining firmoss. Its ascending stems reach 12–15 cm tall and are rarely branched. Unlike Huperzia lucidula, it grows only as individual plants rather than dense colonies. One of the best locations to view this species is Hocking Hills in southeast Ohio. This species is of hybrid origin, with parent species Huperzia lucidula and Huperzia selago. H. porophila hybridizes with H. lucidula to produce the sterile hybrid H. × bartleyi.
