If vernal pools are considered ephemeral then granite pools are downright fleeting. Any organism that specializes in such a habitat must be ready to deal with extremes. That is what makes a little plant known scientifically as Gratiola amphiantha so darn cool. It's what also makes it so darn threatened.
This tiny member of the Plantaginaceae family is native to the Piedmont province of southeastern North America. It lives out its entire life in shallow pools that form in weathered granitic outcrops. One must really think about the specificity of this sort of habitat to truly appreciate what this little aquatic herb is up against. Pools must be deep enough to hold water just long enough but not too deep to allow normal plant succession. They must have just enough soil to allow these plants to take root but the soil must be thin enough to prevent other vegetation from taking over. They must also be low in nutrients to limit the growth of algae that would otherwise cloud the water. Needless to say, this makes suitable habitat for snorkelwort hard to come by.
When such conditions are met, however, snorkelwort can be quite prolific. Seeds of this species germinate in late fall and early winter when only a thing veneer of water covers the equally thin soils. Individual plants form a small rosette that sits in wait until rains fill the tiny pools. Once submerged, the rosettes send up thin stem-like structures called scapes. These scapes terminate in two tiny bracts that float at the waters surface. Between the two bracts emerges tiny, white, five petaled flowers. Submerged flowers are also produced but these are cleistogamous flowers that never open and only self-pollinate. This ensures that at least some seeds are produced every growing season.
When you consider all aspects of its ecology, it is no wonder that snorkelwort is teetering on the edge of extinction. The granitic pools in which it lives are very sensitive to change. It doesn't take much to make them totally unsuitable places to live. Protecting them alone is hard enough. Mining, pollution, littering, and even casual hikers can wipe out entire populations in an instant. Even populations living within the boarders of protected parks have been extirpated by hiking and littering. When you live on the edge, it doesn't take much to fall off. In total, only about 31 populations scattered through Alabama, Georgia, and South Carolina are all that remains of this overlooked little plant.
The upside to all of this is that numerous stake holders, both public and private, are invested in the ongoing success of this species. Private land owners whose land supports snorkelwort populations are cooperating with botanists to ensure that this species continues to find what it needs to survive. Luckily a sizable chunk of the remaining populations are large enough to support ample genetic diversity and, at this point in time, don't seem to be at any risk of destruction. For a little plant like snorkelwort, a little attention can go a long way. If you know a spot where this interesting little plant grows, tread lightly and appreciate it from a safe distance.