Glade Hopping in Bibb County
by: Hunter McBrayer
I recently had the opportunity to botanize at the Bibb County Glades in Bibb County, Alabama, with a small group of plant enthusiasts from The Gardens. We rendezvoused with Tom Diggs, a doctoral student at The University of Alabama at Birmingham studying evolutionary biology. Tom’s research is on the unique array of plants growing at The Glades and the reasons so many of them are endemic to the area.
The Bibb County Glades are truly a remarkable anomaly in the Alabama landscape. Largely ignored by humans until 1992, the glades were considered a treeless barren by most people of that region until Jim Allison, a botanist from Georgia, explored the area. He noticed that several familiar looking plants, upon closer inspection, were unknown species. He continued exploring the area and eventually discovered eight new species of plants; a rare occurrence in today’s world of plant exploration.
Many factors contribute to the fact that the area holds so many endemic plants, but most scientists agree that the primary reason for such a high degree of endemism is the unique substrate on which they grow. Ketona limestone, a very specific type of dolomitic limestone, is the primary geological formation underlying The Glades’ very thin soil; the type of limestone contains very high levels of magnesium. In addition to the preceding factor, arid climate has contributed to the unique evolution of plants that thrive there. One third of Alabama’s twenty-four endemic plant species are found growing at The Glades, which collectively comprise approximately 250 acres.
Although some of these plants were already past flowering, we still had the opportunity to view several of them in flower. This list includes Coreopsis grandiflora var. inclinata, reclining large-flowered tickseed; Dalea cahaba, Cahaba prairie clover; Croton alabamensis var. alabamensis, Alabama croton (a somewhat ubiquitous plants The Gardens); and Spigelia alabamensis (syn. Spigelia gentianoides var. alabamensis, gentian pinkroot. We were also able to examine a population of a new species in the genus Trautvetteria, tassel-rue, which as of yet has not been assigned a name; at present, it is being referred to as Trautvetteria species 1.
Due to the unique character of this area and its rare flora, conservation is of upmost importance. To that end, The Nature Conservancy has acquired 480 acres and named it the Kathy Stiles Freeland Bibb County Glades Preserve. The Preserve is located along a very picturesque section of the Little Cahaba River and makes a delightful day trip; when there take time to appreciate Alabama’s unique natural heritage.
Spigillia gentianoides var. alabamensis
Croton alabamensis, Alabama croton
Trautvetteria species 1