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Is Corn a Grass?

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Created: 12/5/2016      Updated: 3/3/2017

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In this new series, we'll be addressing some common questions from visitors and readers. Do you have a science question that has you stumped? Ask our museum scientists via our form here and we'll answer it on our blog!

Today's Question:

Is corn a grass?

The Short Answer:

A cob of corn may not resemble the green grass growing in your lawn, but if you ask any biologist or botanist, they will tell you that yes, the corn plant is a grass!

 Ears of corn

Photo courtesy of Meg Stewart (CC BY-SA 2.0)

How can that be? First, biologists study the features of plants and animals. Then, biologists create groups of plants and animals that have the same features. This science of grouping similar plants and animals together is called taxonomy. For example, the science of taxonomy says that "mammals" are animals that have fur, give live birth to babies, and feed their babies with milk. In taxonomy, a "grass" refers to a specific group of plants. Grasses have leaves that grow around the stem, and each leaf has a central “vein” that helps support the leaf. Grasses have flowers at the top of their stem in a shape called a "spikelet," and those flowers do not have petals.[1] Using that definition from taxonomy, both lawn grass and the corn plant are grass! When you compare corn and lawn grass like a botanist, you can see how the two plants are related. In the pictures of grass[6] and corn[7] below, what similarities do you see?

Lawn Grass                                                  Corn

What other groups of animals or plants can you think of? What features do they have in common?

If you really want to get confused, ask a botanist about fruits: a botanist will tell you that cucumbers, pumpkins, peanuts, and chili peppers are all fruits! The lesson is, when a botanist offers you a fruit salad, make sure you get a list of ingredients before you accept.

The Long(er) Answer:

The original corn plant does resemble a wild grass plant, but thousands of years of domestication by the native peoples of central Mexico have turned a wild, small-seeded grass known as teosinte into the familiar plant we know today. The kernels of early corn were either ground into a rough flour, or soaked in water, drained, and heated over a fire.

Modern corn is so unlike its genetic predecessor that the origin of corn was a complete mystery to archaeologists until the 1930s when a graduate student named George Beadle experimentally determined the connection between teosinte and the modern corn plant.[2] Even still, corn and teosinte look so different that it took decades longer for the rest of the scientific community to agree with these experimental results!

Maybe the mystery of corn's origin would have been solved sooner had etymologists and botanists been comparing notes: the Aztec word for teosinte, teocentli, means "God's ear of corn," and teosinte is known in some regions of Mexico as madre de maiz or "mother of corn"![3]

The corn we grow today has been so selectively bred and utterly domesticated that corn cannot even survive without humans to plant it into the ground: if a cob of corn kernels falls to the ground and germinates, the cluster of seeds is so dense that they compete against each other for water and nutrients and few seedlings grow to maturity. In only a few generations without human intervention, modern corn would become extinct.[3]

But other cereal crops like wheat, barley, and oats still grow on plants that still obviously look like grass, and those crops have a history of domestication as far back as corn. Why is corn unique?

It's important to remember that small genetic mutations can create profound changes in an organism[4] It's possible that during domestication, random mutations occurred in early corn plants that did not randomly occur in other cereal crops. It's also possible that through genetic engineering, other cereal crops could be created with much larger grains as well. Scientists in Britain claim to have done just that with wheat, claiming to have created a strain of wheat with 40% greater yield than common wheat.[5]

So, that’s that: corn isn’t a vegetable (botanically), but a wonder grass that feeds the western world. The only question that remains is, corn-fed beef or grass-fed beef: what’s really the difference?

Kyle Schiber
Nature Museum Volunteer

[1] Eckardt, Nancy A. (2004) What Makes a Grass? DROOPING LEAF Influences Flower and Leaf Development in Rice. Retrieved December 03, 2016, from http://www.plantcell.org/content/16/2/291.full

[2] Carroll, Sean B. (2010) Tracking the Ancestry of Corn Back 9,000 Years. Retrieved December 03, 2016, from http://www.nytimes.com/2010/05/25/science/25creature.html

[3] Beadle, George W. (1980) The Ancestry of Corn. Retrieved December 03, 2016, from http://users.clas.ufl.edu/dcgrove/mexarchreadings/corn.pdf

[4] Genetic Science Learning Center. (2013, July 1) Evolution of Corn. Retrieved December 03, 2016, from http://learn.genetics.utah.edu/content/selection/corn/

[5] Knapton, Sarah. (2016, November 4) Genetically modified wheat could be grown in Britain from next spring. Retrieved December 04, 2016, from http://www.telegraph.co.uk/science/2016/11/04/genetically-modified-wheat-could-be-grown-in-britain-from-next-s/

[6] https://upload.wikimedia.org/wikipedia/commons/4/44/Grassy_grass_plant.svg, By Kelvinsong (Own work) [CC BY 3.0 (http://creativecommons.org/licenses/by/3.0)], via Wikimedia Commons

[7] https://upload.wikimedia.org/wikipedia/commons/9/98/Maize_plant_diagram.svg, By LadyofHats (Own work) [CC0], via Wikimedia Commons, edited to enlarge text

Do you have a science question that has you stumped? Ask our museum scientists via our form here and we'll answer it on our blog!

Subscribe to the Nature Museum blog and never miss a post! 

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