Native Plants, Habitat Restoration, and Other Science Snippets from Athens, Georgia

Saturday: 11 June 2005

Disappearing Species: Ginseng  -  @ 07:51:31
A couple of years ago a grad student finishing her dissertation on ginseng populations in the north Georgia mountains gifted us with about 300 stratified ginseng seeds. We planted these in various likely locations within the protected boundaries of the property. Most of the seed died, but a couple dozen survived and produced plants in one location. A few days ago I was pleased to see that several of these were flowering.

American ginseng is Panax quinquefolius, and is found in the eastern US as far south as south Georgia and north into Canada. A related species, dwarf ginseng, Panax trifolius, has a similar range. Panax ginseng is Chinese (or Korean, or Indian, or Asian) ginseng, and is not native to the US. As you can tell from the specific epithet quinquefolius, American ginseng leaves have five compound leaflets in a palmate arrangement, like the fingers of your hand around the palm. (Note that the leaf with its leaflets resembles Virginia Creeper (Parthenocissus quinquefolia (there's that "quinquefolia" again!); in fact, there's a little bit of that on the right side of the left-hand pic; but the differences are obvious. Even if not, well, V. Creeper is a vine and ginseng is not.)

The flowers (above) are in an umbel inflorescence, where all the florets emerge from a single point (remember inflorescences)? The seeds they produce are difficult to germinate, requiring many months of cold stratification and probably cyclic warm and cold treatments as well. Since they take so long to germinate they're particularly susceptible to predation by seed-eating animals; most seeds probably die in the wild without producing plants.

From USDA Plants Database, a map of Georgia shows that ginseng populations do occur in our area - I've added pointers to the counties surrounding the observed population(s) in Oconee County to our south. Unfortunately Oconee County, a bedroom community for Athens, is under great stress for development. Our county, Oglethorpe, seems destined to go the same way, a prospect that many residents savor without realizing that the inevitably higher taxes are just going to squeeze many of them out. (And by the way, I've included the three major ecological regions that mark Georgia - the mountain region, the piedmont where we live, and the coastal plain that marks much of the southeast within a couple hundred miles of the Atlantic Ocean and Gulf of Mexico. Georgia truly has an embarrassment of riches when it comes to habitats.)

Panax is in the ginseng family, Araliaceae, which includes a number of genera with plants common to the US. Hedera, or ivy, includes a native species (Canada ivy) and the the horrible, noxious non-native species Hedera helix, English ivy, planted as a groundcover by lazy gardeners. The Araliaceae also includes the genus Aralia, which is represented by such natives as Hercules club or Devil's walking stick (Aralia spinosa), Wild sarsaparilla (Aralia nudicaulis, and American spikenard (Aralia racemosa), all desirable species.

There's no need to go into ginseng's medicinal value here, except in terms of the ecological impact of 250 years of irresponsible harvesting of plants. You can find more than you want to know and this article and this one are good starters. It's the root which is collected, thus killing the plant, and it takes many many years for a plant to produce a suitable root for grinding up into a medicinal form. Thus populations of ginseng are going the way of tigers, elephants, and other organisms that are harvested for medicinal purposes, many questionable, to the point of extinction.

In the Feb 11 2005 issue of Science (Science 307, 920 (2005)), a report appeared by James McGraw at West Virginia University in Morgantown, and Mary Ann Furedi that has alarming implications for naturally occurring populations of American ginseng. A summary on p827 of that issue by Erik Stokstad details the main points of their study.

The authors observed in detail seven populations over five years and discovered that the populations were disappearing. Their conclusion was that a population must have at least 800 plants to have a 95% chance of survival for 100 years. They then examined 36 populations across seven states, and discovered that the largest population among these 36 had only 406 plants; the median size was 93 plants. The culprit? Besides human harvesting, deer browsing. According to Stokstad:

"With few natural predators left, deer are running rampant across much of eastern North America and Europe. In addition to damaging crops, raising the risk of Lyme disease, and smashing into cars, white-tailed deer are eating their way through forests. "This is a widespread conservation problem," says Lee Frelich of the University of Minnesota, Twin Cities. Indeed, on page 920, a detailed, 5-year forest survey of ginseng reveals that deer, if not checked, will almost certainly drive the economically valuable medicinal plant to extinction in the wild....."

"Ginseng is one of the most widely harvested medicinal plants in the United States; in 2003, 34,084 kilograms were exported, mainly to Asia, where wild ginseng root fetches a premium. Although the plant (Panax quinquefolius) ranges from Georgia to Quebec, it is slow-growing and scarce everywhere....."

and "McGraw and Furedi calculate that browsing rates must be cut in half to guarantee a 95% chance of survival for any of the 36 ginseng populations they surveyed. That has direct management implications, says Donald Waller of the University of Wisconsin, Madison. "We should be encouraging the recovery of large predators like wolves. It also suggests we should be increasing the effectiveness of human hunting" by emphasizing the killing of does rather than bucks, he adds. Such deer-control measures are controversial: Reintroduction of predators like wolves faces logistical as well as political hurdles, for example. Meanwhile, the deer keep munching.".

I'm glad then, that our planted and protected population seems to be adjusting, although it may not thrive in the long term. Unfortunately it is not a "natural" population, although it derives from a natural population relatively close by. I have to consider re-evaluating my previous opinion of the coyote populations that seem to have invaded our area. Although deer are a little large for coyotes, they will predate on them occasionally. We've killed off the wolves in this area, and the bobcats that live around here are probably not very good deer predators. It may be that coyotes will serve to help rein in the deer, at least to some extent. As Donald Waller says above, it really would help if deer management through hunting underwent some strategic changes too.

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