Maize

Scientific classification

Kingdom: Plantae

(unranked): Commelinids

Order: Poales

Family: Poaceae

Genus: Zea

Species: Z. mays

Binomial name

Zea mays L.

Maize (Zea mays L. ssp. mays, pronounced /ˈmeɪz/; also known in some countries as corn), is a herbaceous plant domesticated in Mesoamerica and subsequently spread throughout the American continents. After European contact with the Americas in the late 15th and early 16th centuries, maize spread to the rest of the world.

Maize is the most widely grown crop in the Americas (332 million metric tons annually in the United States alone). Hybrid maize, because of its high grain yield as a result of heterosis ('hybrid vigor'), is preferred by farmers over conventional varieties. While some maize varieties grow up to 7 metres (23 ft) tall, most commercially grown maize has been bred for a standardized height of 2.5 metres (8 ft). Sweet corn is usually shorter than field-corn varieties.

Naming conventions

The term maize derives from the Spanish form of the indigenous Taino word for the plant, maíz. This was the form most commonly heard in the United Kingdom. In the United States and Canada the usual term is "corn". This was originally the English term for any grain, but now usually refers to maize, having been shortened from the term "Indian corn." Indian corn is currently often used in the US and Canada to refer specifically to multicolored "field corn" cultivars.

In scientific and formal usage, "maize" is normally used in a global context. Equally, in bulk trading contexts, "corn" is used most. In the UK, Australia and other English-speaking countries, "corn" is often used in culinary contexts, particularly in naming products such as popcorn and corn flakes, but "maize" is used in agriculture and science.

Seeds

The kernel of maize has a pericarp of the fruit fused with the seed coat, typical of the grasses. It is close to a multiple fruit in structure, except that the individual fruits (the kernels) never fuse into a single mass. The grains are about the size of peas, and adhere in regular rows round a white pithy substance, which forms the ear. An ear contains from 200 to 400 kernels, and is from 10–25 centimetres (4–10 inches) in length. They are of various colors: blackish, bluish-gray, purple, green, red, white and yellow. When ground into flour, maize yields more flour, with much less bran, than wheat does. However, it lacks the protein gluten of wheat and, therefore, makes baked goods with poor rising capability and coherence.

A genetic variation that accumulates more sugar and less starch in the ear is consumed as a vegetable and is called sweet corn.

Immature maize shoots accumulate a powerful antibiotic substance, DIMBOA (2,4-dihydroxy-7-methoxy-1,4-benzoxazin-3-one). DIMBOA is a member of a group of hydroxamic acids (also known as benzoxazinoids) that serve as a natural defense against a wide range of pests including insects, pathogenic fungi and bacteria. DIMBOA is also found in related grasses, particularly wheat. A maize mutant (bx) lacking DIMBOA is highly susceptible to be attacked by aphids and fungi. DIMBOA is also responsible for the relative resistance of immature maize to the European corn borer (family Crambidae). As maize matures, DIMBOA levels and resistance to the corn borer decline.

Because of its shallow roots, maize is susceptible to droughts, intolerant of nutrient-deficient soils, and prone to be uprooted by severe winds.

Maize is widely cultivated throughout the world, and a greater weight of maize is produced each year than any other grain. While the United States produces almost half of the world's harvest (~42.5%), other top producing countries include China, Brazil, Mexico, Argentina, India and France. Worldwide production was around 800 million tonnes in 2007—just slightly more than rice (~650 million tonnes) or wheat (~600 million tonnes). In 2007, over 150 million hectares of maize were planted worldwide, with a yield of 4970.9 kilogram/hectare. Production can be significantly higher in certain regions of the world, 2009 forecasts for production in Iowa were 11614 kg/ha. As of 2002 the genetic yield potential of maize had "barely increased in 35 years".

Chemicals and medicines

Starch from maize can also be made into plastics, fabrics, adhesives, and many other chemical products.

Stigmas from female maize flowers, known popularly as corn silk, are sold as herbal supplements.

The corn steep liquor, a plentiful watery byproduct