Saturday, February 4, 2012

The Great Georgia Aster Hunt, Part 1: Talladega Day

Georgia aster in a typical roadside location.

Quick:  What’s the state flower of Georgia?  Did you guess the Cherokee rose?  Ten points for Gryffindor!  

Like many states, Georgia chose a non-native plant for its floral emblem.  Sometimes native-plant geeks toss around homegrown alternatives for our state’s flower.  For a time I was crusading for the Georgia aster (Symphyotrichum georgianum).  It has Georgia in both its common and scientific names, and the flower is a lovely shade of purple.  But it also has one great big drawback: The Georgia aster is so rare that few Georgians have ever laid eyes on one.  And what fun is a state flower you never see?
         This rare plant is only growing rarer.  Georgia aster is a candidate for federal listing under the Endangered Species Act.  About 30 populations had been observed in Georgia, but only 15 small populations survive.[i]  Georgia aster requires prairie-like conditions to grow and seems to prefer disturbed, bare patches of ground. A relict species of post oak savannas that existed in the southeast before widespread fire suppression and the extirpation of large native grazing animals, Georgia aster now grows in places where land management creates similar conditions: roads, railroads and utility rights-of-way like power-line cuts.  The species is further threatened as maintenance practices shift from mowing to spraying herbicides.  Georgia aster’s range includes Alabama, North Carolina, and South Carolina, but has but has been extirpated from Florida.[ii]
Right-of-way marker
         With the populations diminishing not only in numbers but also in size, another knock against the species is the threat of genetic depression.  Plants can reproduce sexually or, in cases like the Georgia aster, they can increase vegetatively through rhizomes (horizontal underground stems which puts out lateral shoots and roots).  All the growth you see in a small community could be from a single clone.  And as we all know by now, poor genetic diversity leads to poor survival rates in all species.
Studying the Means to Thrive
Jenny Cruse-Sanders, Director of Conservation and Research at the Atlanta Botanical Garden, and Danny Gustafson, a professor of Plant Molecular Ecology at The Citadel, are conducting a study of genetic diversity and seed viability for the species across its range.  The hope is that the results can inform the management of the remaining populations.  For instance, with a genetically inbred population, managers could plant asters from other populations and increase the genetic diversity.  Or, if the plants are producing seed but they aren’t growing into plants, then perhaps there is some other issue: Not enough bare soil, mowing at the wrong time, or not mowing often enough.  

This roadside population was mowed while in bloom.  Only the plants hanging over the embankment were spared.
         This is where I come in.  For the study, Jenny and Danny need leaf and seed samples from large and small populations across the aster’s range.  Leaf samples had been collected from Georgia and the Carolinas, but none from Alabama.  Jenny and I were in Alabama to find 6 populations of Georgia aster, 3 large and 3 small; take GPS points; map the boundaries of the community of plants; and take leaf samples for genetic analysis.         
Ryan Shurette and Jenny Cruse-Sanders surveying the large Georgia aster population beneath power-lines in the Talladega National Forest.
Our first stop is the Talladega National Forest, midway between Atlanta and Birmingham.  At the ranger station we meet up with Ranger Ryan Shurette, Forest Botanist, who shows us the way to a field of aster growing in a broad power-line cut.  Prairie plants are never what you call lush, but what we see is certainly robust.  The asters are waist-, even chest-high and festooned with blooms.  At around 2,000 plants, this would turn out to be the largest population I was to see.  Ryan is clearly doing a great job of managing it.  He’s even added out-plantings that are doing quite nicely despite the wretchedly hot, dry weather of this past summer.  
Such a profusion of blooms is truly a rare sight.

A Vital Collaboration
While we were working, employees of Alabama Power showed up to talk to Ryan about upgrades to the power-lines and their impact on the asters.  Jenny and I had lain our transect, and while Ryan shot the breeze with the Alabama Power guys, he also helped record our data. They mainly talked hunting and fishing.  I might have been irritated with Ryan for dividing his attention this way, but I had recently been witness to the importance of having a good relationship with the utility that maintains the power-lines running above rare species.
A few weeks before, I had visited a site in North Georgia with a good-sized aster population.  They, too, were growing beneath power-lines.  Due to some miscommunication, a maintenance crew had sprayed some of the asters with herbicides, intended no doubt for the long-leaf pines that left unchecked would interfere with lines.  On our first visit to the site, the sprayed asters were stressed, and on our second they were a crispy black.  These rare plants were well and truly dead.  Fortunately there were still over 100 healthy plants, but it was a blow nonetheless, and an avoidable one.

The effects of herbicide.  Aster can be seen in lower-left corner, stretching into the middle of the frame.
That the Alabama Power folks were having a nice long chat-and-chuckle with Ryan was not entirely surprising.  Ryan is Southern charm distilled, and it is encouraging that these asters have him as advocate. 
We had just finished our work when the sky opened with the heavy rain shower it had threatened all morning.  We hustled back to our cars.  The way to the asters had involved many turns down largely unmarked roads.  “I can carry you out,” Ryan offered.  When my brain clicked back in gear, I realized he meant take us out, lead us out in his car.  I’ve been living in the South for the better part of three years, and southern idioms still sometimes catch me by surprise.
Perhaps More Than Kissing Cousins
I’m glad that we saw the Talladega population first.  As they almost always are, the Georgia asters were growing among a related species, Symphyotrichum patens, and it gave me the opportunity of making a direct comparison between the two.  The species are difficult to tell apart.  The floral rays of the patens are smaller and lighter in color; the leaves are softer and narrower and lack the scabrous texture of georgianum.  The give-away is that the patens blossom has a yellow center.  I looked closely at the plants and touched the leaves of each species to see and feel the differences.

S. georgianum and S. patens: Can you spot the difference?
As I did so, all kinds of pollinators visited the flowers, traveling back and forth between both species.  Which brings up another tricky variable.  Jenny told me that S. georgianum and S. patens may be hybridizing.  They bloom at the same time and clearly share pollinators, so they have the opportunity to do so.  Moreover, we saw at the Talladega population, as were to see at other sites, individual S. patens that exhibited traits of S. georgianum, and vice versa.  Some S. patens had longer rays and rougher, broader leaves, while some S. georgianum blossoms were lighter in color and some had softer leaves.
None of these observations are conclusive of hybridization, especially since asters tend to exhibit a lot of variation plant-to-plant, but they certainly are suggestive.  This makes the problem of protecting S. georgianum even more complicated: How can you set guidelines for a plant’s protection if you cannot fix its taxonomic description?  You could even say that we may be losing S. georgianum to this process, but you could also say that hybridization is the key to its genetic survival: S. patens is flourishing, while S. georgianum is dwindling.  The S. georgianum traits could survive in a perhaps more vigorous and abundant hybrid.
Thanks to Talladega we had our “search image” firmly in place, which would prove vitally important.  We had sketchy information about the locations of the remaining Alabama populations, many of which had not been visited since the 1990s and, as we were to learn, had drastically diminished in size.  From the Talladega National Forest, we headed southwest to the terminus of the Appalachian Mountains, the haunting country that was once at the heart of Alabama’s coal mining industry.

[i] Chafin, Linda G. Field Guide to the Rare Plants of Georgia. Athens: University of Georgia Press, 2007.  p. 390.
[ii] The information in this paragraph was gathered from the Symphyotrichum georgianum entry in NatureServe Explorer at [updated July 2011].


  1. Carrie, that's awesome! I had heard yall had crossed the border recently. we've got some of the siblings in the Arboretum from the Talladega population, and they are robust.

  2. Thanks, Patrick! It's great to hear that GA aster can do so well in cultivation. I hope to have some in my yard one day. I've got a perfect sun-blasted spot on a gradual slope--my whole yard slopes that way. Moved a bunch of plants (actually the ones that remained after the accidental spray) to Picketts Mill and I am anxious to see how they did.

    Um, who's Carrie? Carrie Radcliffe? floraphile = Hilary Hart. Perhaps it's time I put my picture up here somewhere...