2 rare plant species discovered at Oak Mountain

When Noah Yawn headed out for Oak Mountain State Park in October, he was planning to take part in a survey for a tree found only in Alabama. What he didn’t expect was to also stumble upon a sizable population of another rare plant species: the Georgia aster.

The survey was part of an ongoing effort of the Alabama Plant Conservation Alliance to better understand the range and natural history of the Alabama sandstone oak, a tree found only in six north-central Alabama counties.

Yawn, an undergraduate student assistant in conservation and botany studies at Auburn University, was looking for the rare oak when he first spotted the asters through what he calls “drive-by botany.”

“Driving through the park at 25 miles per hour with my windows down is how I unintentionally discovered the park’s roadside populations of the aster,” Yawn said. “I estimate there are approximately 500 to 1,000 individual flowering stems at the documented roadside sites. These sites are scattered over 1 to 2 miles along Terrace Drive.”

Often considered the Southeast’s largest, prettiest and most purple aster species, this distinctive plant can grow to more than 3 feet tall and features a large flower head encircled with deep purple to lavender petals. Once found in woodlands and Piedmont prairies throughout the Southeast, the Georgia aster is currently found only in a few counties in Alabama, Georgia, South Carolina and North Carolina.

In recent years, a multistate/multiorganization agreement was developed to provide a framework for the conservation and management of Georgia aster throughout its range. The goal of the agreement is to conserve and improve current populations and keep the aster from being federally listed as an endangered species.

“Even the smallest preserved natural areas, including roadsides, can protect extremely valuable and imperiled species,” Yawn said. “The Georgia aster at Oak Mountain State Park represents some of the only populations in Alabama that are protected on state lands, making this all the more exciting.”

Oak Mountain is Alabama’s largest state park at 9,940 acres. The park size and the varied nature of its ridge and valley habitat are partly responsible for the high level of biodiversity found there.

Chris Blankenship, commissioner of the Alabama Department of Conservation and Natural Resources, said these discoveries highlight the importance of public lands, including state parks, to the conservation of rare plant and animal species.

“Alabama’s State Parks, Forever Wild tracts, Wildlife Management Areas and other state lands play a vital role in conserving important habitat for some plants and animals found nowhere else in the world,” Blankenship said. “These locations ensure the public can continue to enjoy the rich diversity of Alabama’s landscape for generations to come.”

While finding the Georgia aster at Oak Mountain was a pleasant surprise, the main focus of the survey was to document the Alabama sandstone oak within the park. Like the Georgia aster, this oak is vulnerable because of its small population numbers and narrow habitat preference.

The Alabama sandstone oak is a long-lived, slow-growing plant. The trees at Oak Mountain State Park could be older than the nearby city of Birmingham. Core samples taken at the Forever Wild Hinds Road Outcrop in Etowah County indicated an average age of less than 100 years for the aboveground tree stems.

As the Alabama sandstone oak grows, its below-ground stems creep along, spreading under the surface of the soil, creating clones of its above ground stems. Because the root system is the oldest part of the tree, age estimates of the above ground stems may not accurately reflect the actual age of the individual trees.

The Georgia aster, now found in only a few counties in four states, was once much more plentiful in the Southeast, according to the ADCNR.

In addition to documenting the existence of the rare oaks in the state park, the survey team found a 90-by-60-foot collection of stems that appears to be a single clonal individual tree. Clonal growth usually occurs at a rate of about an inch or two per year for this species. If this collection of trees is a single individual, it could have taken centuries for it to grow to this enormous size in a low-nutrient environment like the rocky ridges of Oak Mountain.