Zea (plant)

Zea is a genus of flowering plants in the grass family. The best-known species is Z. mays (variously called maize, corn, or Indian corn), one of the most important crops for human societies throughout much of the world. The four wild species are commonly known as teosintes and are native to Mesoamerica. Zea is derived from the Greek name (ζειά) for another cereal grain (possibly spelt). The five accepted species names in the genus are: Zea mays is further divided into four subspecies: Z. m. huehuetenangensis, Z. m. mexicana, Z. m. parviglumis (Balsas teosinte, the ancestor of maize), and Z. m. mays. The first three subspecies are teosintes; the last is maize, or corn, the only domesticated taxon in the genus Zea. The genus is divided into two sections: Luxuriantes, with Z. diploperennis, Z. luxurians, Z. nicaraguensis, Z. perennis; and Zea with Z. mays. The former section is typified by dark-staining knobs made up of heterochromatin that are terminal on most chromosome arms, while most subspecies of section Zea may have none to three knobs between each chromosome end and the centromere and very few terminal knobs (except Z. m. huehuetenangensis, which has many large terminal knobs). Both annual and perennial teosinte species occur. Z. diploperennis and Z. perennis are perennial, while all other species are annual. All species are diploid (n=10) with the exception of Z. perennis, which is tetraploid (n=20). The different species and subspecies of teosinte can be readily distinguished based on morphological, cytogenetic, protein, and DNA differences and on geographic origin. The two perennials are sympatric and very similar and some consider them to be one species. What many consider to be the most puzzling teosinte is Z. m. huehuetenangensis, which combines a morphology rather like Z. m. parviglumis with many terminal chromosome knobs and an isozyme position between the two sections. Considered to be phenotypically the most distinctive, as well as the most threatened, teosinte is Zea nicaraguensis.