Lepidium meyenii, known as maca or Peruvian ginseng, is an edible herbaceous biennial plant of the family Brassicaceae that is native to South America in the high Andes mountains of Peru and Bolivia. Its use increased after the late 1980s, when it was commercially discovered. It is grown for its fleshy hypocotyl that is fused with a taproot, which is typically dried but may also be freshly cooked as a root vegetable. As a cash crop, it is primarily exported as a powder that may be raw or processed further as a gelatinized starch or as an extract. If dried, it may be processed into a flour for baking or as a dietary supplement.
Description Maca is the only member of the genus Lepidium with a fleshy hypocotyl, which is fused with the taproot to form a rough inverted pear-shaped body. Traditionally, native growers have acknowledged four varieties of maca based on their root color: cream-yellow, half-purple, purple, and black; varying levels of anthocyanin are primarily responsible for the color differences. Maca hypocotyls may be gold or cream, red, purple, blue, black, or green. Each is considered a genetically unique variety, as the seeds of the parent plants grow to have roots of the same color.
The growth habit, size, and proportions of maca are roughly similar to those of radishes and turnips, to which it is related, but it also resembles a parsnip. The green, fragrant tops are short and lie along the ground. The thin, frilly leaves sprout in a rosette at the soil surface, not growing more than 12–20 cm (4+1⁄2–8 in) in height. The leaves show a dimorphism according to the reproductive stage. They are more prominent in the vegetative phase and continuously renew from the center as the outer leaves die. The off-white, self-fertile flowers are borne on a central raceme, and are followed by 4–5 mm (5⁄32–3⁄16 in) siliculate fruits, each containing two small 2–2.5 mm (1⁄16–1⁄8 in) reddish-gray ovoid seeds. Seeds are the maca's only means of reproduction. Maca reproduces mainly through self-pollination: it is an autogamous species. The genome consists of 64 chromosomes. Maca is a short-day plant from experiments with different day lengths. Some sources consider the maca an annual plant, as in favorable years, it can complete a lifecycle within a year. Maca contains glucotropaeolin, m-methoxyglucotropaeolin, benzyl glucosinolates, polyphenols, (1R,3S)-1-methyl-1,2,3,4-tetrahydro-β-carboline-3-carboxylic acid (MTCA), and p-methoxybenzyl isothiocyanate. Alkamides are also present in maca. Maca contains several N-benzylamides referred to as macamides that are structurally related to anandamide.
Taxonomy Antonio Vázquez de Espinosa described the plant following his visit to Peru circa 1598, and Bernabé Cobo described this plant in the early 17th century. Gerhard Walpers named the species Lepidium meyenii in 1843. In the 1990s, Gloria Chacon further distinguished a different species. She considered the widely cultivated natural maca of today to be a newer domesticated species, L. peruvianum. However, most botanists doubt this distinction and continue to call the cultivated maca L. meyenii. The Latin name recognized by the United States Department of Agriculture similarly continues to be Lepidium meyenii. It has been debated whether it is botanically correct to consider meyenii and peruvianum to be distinct from one another. A 2015 multi-center study found differences in taxonomy, visual appearance, phytochemical profiles and DNA sequences when comparing L. meyenii and L. peruvianum, suggesting that they are different and that their names should not be considered synonyms.
Cultivation Specific phenotypes (in maca, 'phenotype' pertains mainly to root color) have been propagated exclusively to increase commercial interest.
Growth conditions The natural environment of the maca is at 11–12ºS latitude and at an elevation of 3,800–4,400 m (12,500–14,400 ft) above sea level. At this elevation, temperatures of the growing season vary from −2 to 13 °C (28 to 55 °F) in monthly mean minimum or maximum, respectively. Temperatures can decline, however, as low as −10 °C (14 °F) and frosts are common. Of the cultivated plants, maca is one of the most frost tolerant. Strong winds and sunlight are also characteristics of the native habitat of the maca. Maca today is still mainly cultivated in Peru, in the high Andes of Bolivia, and to a small extent also in Brazil. Maca can be cultivated beyond its natural elevation range, over 4,400 m (14,400 ft) above sea level.
Growth
The seedlings usually emerge about one month after sowing, with the onset of the rainy season in October. In the vegetative phase, from May to June, the lower part of the hypocotyl, as well as the upper part of the tap root, grows in size. After 260 to 280 days, it is formed into the harvestable hypocotyl. If the root is left in the soil, it is dormant for two to three months in the time of the cold, dry season until August. Then, it will form a generative shoot on which the seeds ripen five months later. One plant can form up to 1,000 tiny seeds, 1,600 of which weigh about one gram. Thus, only relatively few plants are needed for propagation. The cultivated plants are selected for preferred size and color, then placed 50–100 mm deep in pits with alternate layers of grass and soil to protect them from drying out. They are fertilized heavily, as maca is an exhaustive crop of soil. The cultivation cycle is strictly linked to seasonality. Traditionally, land preparation was done by hand. Nowadays, tractor plowing is also used. As maca grows on sites where no other crops can be cultivated, it is often found after long fallows of sheep grazing pastures. Maca croplands, thus, traditionally are only fertilized with sheep and alpaca manure; however, fertilizer application could prevent soils from depleting in nutrients. Weeding or pesticide application usually is not necessary. The climate is not suitable for most weeds or pests. Nearly all maca cultivation in Peru is carried out organically; maca is seldom attacked. Maca is sometimes interplanted with potatoes, as it is known to maca farmers that the plant naturally repels most root crop pests.
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