The aerial part of maca has 12 to 20 leaves and the foliage forms a mat-like, creeping system of stems that grows close to the soil. The underground portion of the plant, known as the hypocotyl, is a storage organ and is the part that is used commercially. The hypocotyl can be a variety of colors, such as red, purple, cream, yellow, or black, and is 10 to 14 cm long and 3 to 5 cm wide; a cold climate seems to be critical for its formation or growth. Maca is cultivated in a narrow, high-altitude zone of the Andes Mountains in Peru. Maca has one of the highest frost tolerances of any cultivated plant, allowing it to grow at altitudes of 3,800 to 4,800 m above sea level in the puna and suni ecosystems, where only alpine grasses and bitter potatoes can survive. Maca and several related wild species also are found in the Bolivian Andes. While traditionally cultivated as a vegetable crop, use for its medicinal properties has become more prominent in Peru.