An assortment of caryopses. Credit: Fir0002
From Monday’s New York Times, in an article about the slow season in New York State’s legislature:
Earlier this year, Senator Michael F. Nozzolio, an upstate Republican, introduced legislation that would make sweet corn the state vegetable. …
But when the bill came up for debate in the Senate on Tuesday, it quickly earned the disapproval of Senator Martin Connor, a Brooklyn Democrat.
“As everyone knows, corn is a grain,” he said. “And I would propose that we make sweet corn the New York State official grain.” …
“The criteria is whether it comes from the reproductive part of a plant or the vegetative part of the plant,” Dr. [Marvin P.] Pritts said. “If it comes from the reproductive part of the plant, it’s a fruit. If it comes from the vegetative part of the plant, it’s a vegetable.”
Botanically speaking, corn is a caryopsis, or dry fruit — popularly known as a grain.
Dr. Pritts allowed that corn, like a tomato, is eaten like a vegetable, “so to a normal, everyday person, it’s a vegetable.”
So what makes a grain, anyway?
In botany, a caryopsis is a type of simple dry fruit — one that is monocarpelate (formed from a single carpel) and indehiscent (not opening at maturity) and resembles an achene, except that in a caryopsis the pericarp is fused with the thin seed coat.
The caryopsis is popularly called a grain and is the fruit typical of the family Poaceae (or Gramineae), such as wheat, rice, and corn.
The term grain is also used in a more general sense as synonymous with cereal (as in “cereal grains”, which include some non-Gramineae). Considering that the fruit wall and the seed are intimately fused into a single unit, and the caryopsis or grain is a dry fruit, it is not surprising that in general usage little concern is given to technically separating the terms “fruit” and “seed” in these plant structures. In many grains, the “hulls” to be separated before processing are actually flower bracts.
– Caryopsis, Wikipedia
Glad we cleared that up!