Taken for ‘granite’: The flowers of flatrock habitat

I recently stumbled on an especially interesting habitat while exploring the flora and fauna on a site that once held granite quarries.

I was with Crystal Cockman from the LandTrust for Central North Carolina and Nell Allen from the North Carolina Zoo. Today trees and luscious foliage cover the property just east of Salisbury. But the old, forgotten quarries left it hilly with large, exposed granite rocks – and granitic flatrock.

Though the granitic flatrock we saw, and flatrock in general, might seem like a landscape inhospitable to plant and wildlife, in fact it fosters an abundant community of diverse flatrock species, some of which we encountered. A granitic flatrock community, characterized by large slabs of granite overlaying soil, is home to many species of mosses, lichens, cacti and other plants that thrive in low soil levels. Although historic quarrying on the property disturbed and likely changed the level at which the flatrock resided, we can be sure the granitic flatrock community was natural, because some of the plant species we encountered grow only on exposed flatrock, and not surrounding woods.

Perhaps the most abundant species we found were Grimmia laevigata, or dry rock moss, and Phemeranthus teretifolius, also known as the quill fameflower. Both grow only on exposed flatrock. Dry rock moss can grow into large patches, and its color varies from almost black when dry to deep green when wet. Quill fameflower is a small, succulent plant native to the Piedmont of North Carolina and surrounding states. This native flatrock species produces small purple flowers up to seven months of the year, which attract diverse species of bees.

The quill fameflower is related to purslane. It grows only on exposed flatrock. Photo: Crystal Cockman

Another species we encountered at the flatrocks, and perhaps my favorite, was Opuntia humifusa, better known as the Eastern prickly pear cactus. This species of prickly pear is common in coastal areas of North Carolina because of the sandy soil and also occurs, but rarely, in the N.C. Piedmont. This prickly pear cactus species produces large, vibrant yellow flowers starting late spring, which later become pear-shaped fruit. Surprisingly, the fruits are edible once they ripen to a magenta color and the prickly spines are removed.

The granitic flatrock community we encountered also had vernal pools, which are temporary and shallow pools that typically lack fish but can have frogs and tadpoles. These pools are present in winter and spring but typically dry up for summer and fall. They can be habitat for many plant species, particularly wildflowers in the Piedmont of North Carolina. These species include the one-flowered sandwort (Minuartia uniflora), also known as one-flower stitchwort, endangered in North Carolina. Though we did not get to see any one-flowered sandwort during our trek into the granitic flatrock community, we saw patches of blooming Mononeuria glabra, or Appalachian sandwort, as well as black raspberry (Rubus occidentalis) near the pool. The black raspberry was especially interesting because it is scarce in the Piedmont, and because the pink flowers we observed, rather than the typical white, are unusual for the species.

Though the property we explored is privately owned, the public can visit similar granitic flatrock communities at other locations. The scenic Little Long Mountain, part of the Uwharrie National Forest, hosts granitic flatrocks and is a perfect picnic and hiking destination. There are quill fameflowers, patches of prickly pear cactus, and other plants common to granitic flatrock communities. Dunn’s Mountain Park, near the property we explored, also has public access to granitic flatrock communities, as well as other family-friendly activities.

Lizzy Nist is a Stanback intern with the LandTrust for Central North Carolina. She is a rising sophomore at Duke University majoring in Earth and Ocean Sciences.

Lizzy Nist