I live in the Blue Ridge Mountains, part of the Appalachian Mountain Range that runs from southern Pennsylvania down into north Georgia. This area is basically poor (except for the coal) and was heavily populated by the Scots-Irish. The settlers then and now had a hardscrabble life on land too steep to cultivate except for small home gardens, a few chickens and maybe a cow. Much of their food supply came from hunting, and in their growing knowledge of the woods they found wild ginseng, a lucrative cash crop.
Wild American ginseng (Panax quinquefolius, called ‘Sang’ by the locals) is highly prized by the Chinese, selling for far more than cultivated (field farmed) ginseng or Asian ginseng (Panax ginseng). The roots are ground and taken orally as aphrodisiacs, stimulants and used in the treatment of Type II Diabetes. Wild ginseng has become increasingly scarce in the Blue Ridge due to over-harvesting. It takes 4-6 years for a ginseng root to reach maturity and unscrupulous hunters often dig small roots to sell, rather than letting them mature. Dried wild ginseng roots sell for more than $400 per pound, while field-cultivated may only bring $10 per pound.
To combat the wild ginseng shortage, several states (ME, VA, TN and NC) have started programs to encourage woods-grown ginseng, restoring the natural habitats and preserving the remaining wild ginseng. I have heard it said woods-grown ginseng has comparable value to mature wild ginseng although many of the sang hunters around here dispute it. I know hunters who note where ginseng seeds are maturing and will come back in the fall to pick them and plant near the ‘mother plant’. They take great pains to hide their growing plants, often unsuccessfully.
American ginseng Panax quinquefolius http://davesgarden.com/guides/pf/go/450/ has 5 leaves and a yellowish-green sparkly wand shaped flower head. The green immature seeds turn red in the fall when ripe. The seed does not store well and should be planted asap. It can grow 12-18” tall but is usually much shorter. Ginseng grows in full shade, in acidic, moist humus-rich soils in USDA zones 4a-7b. It is deciduous and often covered in a bank of dead leaves in fall and easy to overlook. It can be grown in the home garden with the right conditions.
The American ginseng is Panax quinquefolius and the Asian ginseng is Panax ginseng. The botanical name Panax means "all-heal" in Greek, and was applied to this genus because Linnaeus was aware of its wide use in Chinese medicine. 
According to Traditional Chinese Medicine, American ginseng promotes Yin energy (cold, negative, female) while Asian ginseng promotes Yang energy (hot, positive, male). There are similarities as each is considered an adaptogen (a substance that strengthens the body) and considered valuable to those recovering from injury or illness. There have been positive reports of Asian ginseng used to treat cancer, heart disease and respiratory problems. American ginseng studies in laboratory animals have reported positive results in protecting against heart attacks and in protecting the kidneys against damage from methamphetamine usage. 
Herbs should only be taken with care and under the supervision of a qualified health care provider.
Just for Fun: Dessert of Quail Eggs with Ginseng
10 grams (0.35 oz) American ginseng
15 grams (0.52 oz) dried mushrooms
20 grams (0.70 oz) Poria (a Chinese herb)
10 quail eggs (cooked, de-shelled)
2 oz. water chestnut powder
Rock sugar according to taste
21 oz. water
Chop soaked mushrooms and discard tough ends. Place mushrooms, American ginseng, rock sugar, poria and boiling water into a soup pot and steam on low heat for 1 hour.
Add eggs and steam for another 15 minutes. Melt water chestnut powder with some water and add into steamed dessert and stir. Add sugar to taste.
Thanks to DiOhio, enya_34 and wakivey for their photos in Plantfiles. The ginseng root photo is used by permission from iStockPhoto.com/wekwek
U.S. Scientific Authority Findings on American Ginseng
Producing and Marketing Wild Simulated Ginseng in Forest and Agroforestry Systems:
One Place to Buy Stratified Ginseng Seeds or Rootlets