Maize (called corn in North America) is a fascinating plant. It is an annual grass whose female inflorescence is an axial raceme (the cob) of spikelets (becoming grains, a.k.a. kernels), each with a long, silky style protruding from a spathe (the husk). There is always an even number of spikelets, ranging from 8-32, depending on cultivar, and usually just one or two cobs per plant. The male flower is a tassel on the top of the plant. Pollen gets from the tassels to the silky styles by wind and gravity, not insects. The seed heads (cobs or ears) are larger than in any other species of grass. Some kinds of maize produce ears as long as 24 in (60 cm); another kind has tiny ears no longer than an inch (2.5 cm). There are literally thousands of maize cultivars. Different cultivars of maize have been developed for increased sugar content, increased starch content, greater size (up to 20 ft, or 6 m tall), smaller size (as little as 2 ft or 60 cm tall), earlier maturity, greater productivity and for popping. There are ornamental cultivars that produce colored kernels and colored husks. And, of course, Monsanto has given the world a whole slew of different types of "Roundup Ready CornT" which are immune to RoundupT herbicide, and so can be harmlessly drenched with the weed killer.
Collections of colorful corn varieties are offered for sale in the autumn for use in arrangements and other decorations. The red roundish one on the right is called strawberry corn - click here to download a large version to take a closer look.
Major categories (sometimes called races) of corn include flint corn which has small, very hard grains, was popular with Native Americans, and was usually dried before use; flour corn (a.k.a. squaw corn), which has large ears with kernels high in starch content, and is usually ground into meal; dent corn (a.k.a. field corn), which has an an indentation on one side of the grain, large starchy kernels and is usually used for animal feed; and sweet corn, which has kernels that are wrinkled and keeps its carbohydrates as sugars when ripe, unlike the other kinds of corn that convert their sugars into starches as they ripen. The new "super sweet" varieties don't even convert their sugars to starches after being picked.
Fresh white sweet corn pausing to pose on its way to a boiling pot of water.
Location Zea mays is a cultigen that does not occur in the wild. It was first domesticated from a wild ancestor that has apparently gone extinct in what is now Mexico more than 5000 years ago. Since pre-Columbian times, maize has been the main cereal crop in Mexico, Central America, the Caribbean and much of South America. Christopher Columbus "discovered" maize in Cuba in 1492 and brought some back to Spain. It spread throughout the Old World and today corn is the most important, or second most important cereal crop (behind rice) in tropical and subtropical climates everywhere. Clearly, maize is the most important food crop to have come from the New World to the Old World.
This heirloom variety has red silk sticking out of the cobs. These are actually styles - the elongated part of the (female) pistils between the ovaries and (ending at) the stigmas (which accept the pollen). The word "tassels" is used for the filaments of the (male) stamens, which end in anthers that release the pollen.
It takes a lot of garden space to grow corn, but you can underplant it with beans that will climb up the stalks and with squash plants that will find the sunny gaps. Corn (like most grasses) is pollinated by wind and gravity, and therefore should be grown in blocks (not rows), with about 4 in (10 cm) between plants. This way, no matter which way the wind blows, some pollen will likely reach some silks. Do not plant different cultivars near each other as they will hybridize and produce a crop with unpredictable characteristics. Light: Corn is grown in full sun. Moisture: Corn requires about an inch (2.5 cm) of rain or irrigation water per week. Hardiness: USDA Zones 3-11. Corn is a frost tender annual. Depending on cultivar, corn requires 65-110 frost free days from germination to harvest. There are varieties in South America that need eleven months to mature. Propagation: Corn cannot grow without human husbandry because the husks do not open on their own, and the ears, with their seeds, simply rot on the plant. Corn grains (kernels, seeds) are planted in situ after all danger of frost has past; optimum soil temperature for germination is 70-80 F (21-27 C). In cool-temperate climates, corn can be started in small pots a few weeks before soil temperatures become acceptable, then hardened off and transplanted outside.
Steve's flying squirrel friend liked to drop by for night time corn-on-the-cob feasts.
Corn is grown for human and animal food and for cooking oil. The kernels (grains) are milled into flour to make doughs for various uses such as snack foods, tortillas, bread, pone, etc. The grains are crushed to make hominy for Yankees and grits for southerners. Beer and whiskey for all are made by fermenting the grains. Varieties with a hard seed coating (the endosperm) explode when heated and are used for popcorn. Ornamental varieties are grown for colorful husks and kernels used in dried arrangements. Huitlacoche, or maize smut (Ustilago maydis), is a fungus that sometimes grows on corn plants. It appears as a disorganized glossy gray mass and is considered a gastronomical delicacy.
I have given up trying to grow corn in my own backyard garden. I don't have enough room to grow a large stand, and in my little plot, the squirrels (I can't shoot the white ones!) open the corn husks at maturity and eat the kernels on the tip of the ear, then move on the next ear until they have opened them all.
Two other cereals - wheat and rice - have better protein concentrations and quality (for humans) than maize. But, with the inclusion of beans in their diet, Native Americans had a balanced source of complete protein (that is, all the essential amino acids).