The teosintes are a group of large grasses of the genus Zea found in Mexico, Guatemala, and Nicaragua.
There are five recognized species of teosinte: Zea diploperennis, Zea perennis, Zea luxurians, Zea nicaraguensis, and Zea mays. The last species is further divided into four subspecies: huehuetenangensis, mexicana, parviglumis, and mays. The first three subspecies are teosintes; the last is maize, or corn, the only domesticated taxon in the genus Zea. The species are grouped into two sections, sect. Luxuriantes, with the first four species, and sect. Zea with Zea 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 sect. Zea may have 0 to 3 knobs between each chromosome end and the centromere and very few terminal knobs (except Z. m. huehuetenangensis which has many large terminal knobs). The two perennials are thought to be one species by some.
The term "teosinte" accompanied the first Guatemalan accession and seems not to have been used in Mexico. The name is also used locally to refer to other plants: some members of the related genus Tripsacum and also to a cycad.
There are both annual and perennial teosinte species. Zea diploperennis and Z. perennis are perennial, while all other taxa 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, although the two perennials are sympatric and very similar. 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 Z. nicaraguensis. This teosinte thrives in flooded conditions along 200 meters of a coastal estuarine river in northwest Nicaragua.
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