LIMA, Peru — It's small and looks like a radish. Although smelly, many Peruvians consider the root an alternative to ginseng and Viagra. 

Frost-resistant Maca grows in the frigid Andean highlands. It's been used in this South American country for centuries to boost stamina and sex drive.

Archaeologists have discovered traces of maca cultivation at sites dating back 2,000 years in the central Andes, where the plant thrives naturally at 13,000 feet above sea level.  Spanish conquistadors are said to have accepted bushels of the protein-rich root from local communities during the 16th century as tax payments. Chroniclers also reported that Peru's various pre-Hispanic groups bartered with maca, used it for peace offerings and offered it to their mountain and sun gods. Today, Peruvians eat maca fresh, dried, boiled into porridge or ground into powder and mixed with water or milk in a drink that tastes somewhat like butterscotch with an earthy aftertaste. Just as the Incas did centuries ago, many Peruvians swear by maca's energizing and aphrodisiacal powers. It is also touted as a tonic for a host of other health problems, including post-menopause syndrome and stress. 

For scientists, the jury is still out. 

Nutritionists say the root packs a powerful dose of amino acids, vitamins and minerals, particularly magnesium and phosphorous. But no major independent studies have been published about its effects. "It's still what you call an alter-native medicine," says Dr. Alberto Tejada, a urologist for the Fertility Institute in Lima

"What we do know is that it is energizing, that it increases sexual stimulus, that it improves the dis-position toward sexual activity and improves mood," he says. Hersil, a Peruvian pharmaceutical company that plans to market maca-based tablets internationally, says small-scale research it financed at Peru's Cayetano Heredia University found that maca in-creased men's sex drive and sperm counts. 

Dr. Fernando Cabieses, a neurologist who for two decades has studied Peru's treasure trove of medicinal plants, supervised the study, which involved 60 volun-teers who were divided into two groups. One group took maca tab-lets for 12 weeks, the other placebos. 

"Its a very interesting study, with interesting results, which need to be corroborated by other scientific groups to see if this repeats," Dr. Cabieses says.  Jose Luis Silva, Hersil's assistant general manager, sees opportunities for maca to compete for some of the $2 billion now spent around the world each year on ginseng, a root highly prized in Asia for its energy-giving and curative properties. Overseas sales would be a boon for this impoverished nation's rural farmers, many of whom eke out liv-ings in rugged countryside.  Maca could be just the beginning, Peruvians hope. Dozens of native plants are used as natural medicines by indigenous people.  Among those herbal medicines is mashua, a root that is said to inhibit sex drive. It was reputedly given to Inca warriors to help keep them focused on battle. Today, Peruvian women are said to slip mashua into their husbands' meals before extended business trips so their minds focus solely on business.