Maca
Also known as “Peruvian Ginseng.” Maca is the tuberous root of a South American plant, Lepidium meyenii. Maca is used both as a vegetable and medicinal food to improve libido and fertility. Maca is highly nutritious, and has been shown to improve memory/learning and depression in animal experiments. It also has positive effects on menopausal symptoms via non-hormonal mechanisms. One variety, black maca, also increased sperm count and motility in rats.
Maca is often added to “male enhancement” products, although the doses are generally too low for any significant effects.