Zea
- Zea is also the abbreviation of the botanist Francisco Antonio Zea (1770-1822)
The genus Zea includes several species of poaceae or grasses of American origin, of which the only one with economic value is Z. mays mays, known as corn, a cereal of high energy value cultivated for human and animal consumption. All other species and subspecies receive the common name of teosinte.
Description
They are robust annual or perennial plants, cespitose or rhizomatous; stems many-internoded, stout, often with stilt roots; monoecious plants. Leaves mostly stem-like; ligule a membrane; blades large, linear, flattened. Unisexual inflorescences; inflorescence staminate a panicle of racemes, terminal, internodes of the rachis not jointed, slender; spikelets staminate paired, unilateral, one spikelet of each pair sessile or subsessile, the other pedicelate, pedicels free, glumes herbaceous, multiveined, upper and lower florets similar, both staminate, lemma and palea hyaline, lodicules 3, stamens 3; pistillate inflorescence a solitary, axillary, slender spike, wrapped in 1–numerous spathes, rachis internodes disarticulating, swollen, sessile pistillate spikelets, solitary, couplets in 2 rows, deeply sunken and nearly enveloped by rachis internode (dome), callus oblique, truncate or flattened, lower glume indurate, smooth, inconspicuously winged at tip, upper glume membranaceous, lower floret sterile, lower lemma small, hyaline, lower palea small, hyaline, upper floret pistillate, lodicules absent, style and stigma solitary, very long, tips extending beyond enveloping spathes. Fruit a caryopsis; dotted thread. In Zea mays ssp. mays the pistillate inflorescence is a massive, tough, fibrous ear, rachis internodes not disarticulating, spikelets paired, sessile, polistic in 4–36 rows, superficially inserted into the ear, callus acute, membranaceous glumes, lower floret usually sterile or rarely pistillate, upper pistillate floret, lemmas, and paleas membranaceous.
Several other species in the genus, known collectively as teosintes, have evolved a maize-like appearance as a countermeasure to their selective eradication by farmers.
The species of the genus Zea generally have a hollow stem, similar to that of bamboo, from which, depending on the species, they may or may not have ramifications. Although Z. nicaraguensis and Z. perennis are perennials, most species are annuals. Despite their short life cycle, they reach several meters in height.
Virtually all populations of teosinte are threatened or at risk: Zea diploperennis occurs in an area of only a few km²; Zea nicaraguensis survives in approximately a single subpopulation of 6000 plants in an area of 200×150 m. The governments of Mexico and Nicaragua have recently moved to protect wild populations of teosinte, using both in-situ and ex-situ conservation methods. There is much scientific interest in these beneficial works, and in others such as insect resistance, perennialism, and flood tolerance.
Taxonomy
The genus was described by Carlos Linnaeus and published in Species Plantarum 2: 971. 1753.
- Etymology
Zea: generic name that would be a word of Greek origin, derived from zeo which means to live. But Pliny the Elder (Historia naturalis,18, 81) uses the term Zĕa, æ to refer to Triticum spelta (spelt, also known as escaña mayor or spelled major).
Accepted taxa
It includes 40 described species and of these, only 6 accepted.
- Zea diploperennis Iltis, Doebley & R.Guzmán
- Zea luxurians (Durieu & Asch.) R.M.Bird
- Zea mays L. - "maize"
- Zea mays mays
- Mexican Maya Zea H.H.Iltis
- Mexican Zea (Schrad.) Kuntze, Reeves & Mangelsd.
- Zea nicaraguensis Iltis & B.F.Benz
- Zea perennis (Hict.) Reeves & Mangelsd.