Maca Species classification
The Cruciferae (Brassicaceae) family contains many important crop plants and comprises approximately 3000 species. According to Rehm and Espig (1991), crops of economic importance are:
• starch plant - maca (Lepidium meyenii)
• oilseeds - rapeseed (Brassica napus) and crambe (Crambe abyssinica)
• vegetables - cauliflower, common cabbage, Brussels sprouts, etc. (Brassica oleracea var botrytis, var capitata, var gemmifera); Chinese cabbage (B. rapa subsp. chinensis); garden rocket (Eruca vesicaria subsp. sativa); watercress (Nasturtium officinale); radish (Raphanus sativus); garden cress (Lepidium sativum).
• spices - mustard (Brassica nigra, Brassica juncea and Sinapis alba)
• fodder - fodder kale (Brassica spp.), fodder radish (Raphanus sativus).
The species in the Brassicaceae are classified in three large cosmopolitan sections . - Dileptium, Monoploca and Lepidium - and three minar sections restricted to the Old World - Lepia, Lepiocardamon, Cardamon (Thellung 1906; Mummenhoff et al. 1995).
The genus Lepidum belongs to tribe Lepidieae and section Monoploca of the Brassicaceae family (Thellung 1906) and consists of approximately 175 species (Mummenhoff et al. 1992) being the largest genus in the Brassicaceae (Hewson 1982). Maca (Lepidium meyenii Walp. in Nov. Act. Nat. Leopold. Carol. 19, Suppl. 1 (1843) 249) is the only species cultivated as a starch crop.
In the genus three other species are cultivated (Hanelt 1986; Mabberley 1993):
1. the garden cress or land cress (Lepidium sativum L) is grown worldwide and is used at the cotyledon or seedling stage as a salad component
2. dittander (L. latifolium L) was a cultivated salad plant of the Ancient Greeks and is used as a medicinal plant in the Canary Islands to alleviate renal lithiasis. According to studies of Navarro et al. (1994), this species has diuretic action.
3. poor man' s-pepper (L. virginicum L) is used as a leafy vegetable (weed in maize) by the Tarahumara Indians in Mexico.
The taxonomic status of maca, the Andean cultivated species of Lepidium, has been questioned by Chacón (1990), who proposed to change its name L. meyenii Walp. to L. peruvianum Chacón sr. nov., based on morphological observations and comparative analysis of herbarium specimens in Germany and the USA. Additionally, the original collections of L. meyenii were done outside the present range of distribution of maca, namely Puna in Peru. Although it is believed that in Inca times maca was cultivated in Puna, there is no evidence of this crop being cultivated there at the present time (M. Holle, pers. comm.). Later, other accessions collected in Bolivia and Argentina were also classified as L. meyenii. After superficial morphological inspection, however, no resemblance to maca can be seen in these early herbarium specimens, which in many cases are not in optimal shape. Therefore the species name change seems justifiable, although further taxonomic research is required to salve this problem.
Common names of the species are (National Research Council1989): English: maca, Peruvian ginseng.
Quechua and Spanish: maca, maka, maca-maca, maino, ayak chichira, ayak willku.
At least seven wild species of Lepidium, including the cultivated one, have been reported in Peru by Brako and Zarucchi (1993) from the departments of Ancash to Puno. In addition, other Andean species have been collected in Ecuador, Bolivia and Argentina (M. Hermann, pers. comm.). Practically nothing is known about the origin of these species and even less about their possible relationship to maca. Although maca is an octoploid, the Andean wild species of Lepidium surveyed so far include both tetraploid and octoploids (Quirós et al. unpublished). A survey of approximately 30 different cultivars of maca and 21 wild species from Ecuador, Peru and Bolivia, with Randomly Amplified Polymorphic DNA (RAPD) and Restriction Fragment Length Polymorphism (RFLP) markers for rDNA, cruciferins, napins and a self-incompatibility sequence (Kianian and Quirós 1991), disclosed very low polymorphism among cultivars. Phylogenetic distances calculated on the basis of 75 RAPD markers indicate that none of the wild species so far screened is closely related to maca (Quirós et al., unpublished). Tentatively three wild species could be
identified by one of us (CFQ) when comparing them with herbarium specimens at the UC Berkeley Jepson herbarium, Berlin-Oahlem Herbarium in Germany, Museo de Historia Natural Javier Prado in Lima and Cesar Vargas Herbarium at the Universidad del Cusco The species' identities in the collection were confirmed by Or 1. AI-Shahbaz at the Missouri Botanical Garden. These species are L. bipinnatifidum Oesvaux, L. kalenbornii CL. Hitchcock and L. chichicara Desvaux. Tetraploid and octoploid forros were found for L. bipinnatifidum and L. chichicara. Lepidium kalenbornii consisted only of tetraploid accessions. In 1996 we collected in the departments of Cusco and Apurimac at 3600 to 3950 mas asl and found the same wild species. No cultivated maca was detected in this region.
