Zea (genus) - Description

Description

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.

Teosintes strongly resembles maize in many ways, notably their tassel (male inflorescence) morphology. Teosintes are distinguished from maize most obviously by their numerous branches each bearing bunches of distinctive, small female inflorescences. These spikes mature to form a two-ranked 'ear' of five to ten triangular or trapezoidal, black or brown disarticulating segments, each with one seed. Each seed is enclosed by a very hard fruitcase, consisting of a cupule or depression in the rachis and a tough lower glume. This protects them from the digestive processes of ruminants that forage on teosinte and aid in seed distribution through their droppings. Teosinte seed exhibits some resistance to germination but will quickly germinate if treated with a dilute solution of hydrogen peroxide.

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