What Is a Caryopsis? The Grain Fruit of Grasses
A caryopsis is the dry, one seeded fruit of the grass family, which we usually call a grain. The Virginia Master Gardeners fruit table says its seed coat is fused to the pericarp, and lists corn, cereals and bamboo.
The short answer
A caryopsis is a grain, a whole fruit with one seed inside, but the fruit wall and seed coat grow together so tightly that the kernel looks and acts like a seed. Corn kernels are a familiar example, and every grass makes this fruit type.
What is a caryopsis?
The Virginia table defines it as the one seeded fruit of Poaceae with the seed coat fused to the pericarp. Inside, NC State Extension says a seed holds an embryo, an endosperm with stored food and a seed coat. Compare with cannabis seed anatomy.
Why is a grain a fruit?
NC State Extension says a fruit is a ripened ovary that holds one or more seeds. A grain ripens from the ovary and holds one seed, so it’s a fruit. It sprouts like a seed, and NC State notes the radicle is the first part to appear, as in how to germinate cannabis seeds.
Where do you see caryopses?
On any grass, from lawn grass to corn and bamboo, per the Virginia table. Corn kernels fill where pollen reaches the silks, University of Minnesota Extension explains. Grass leaves are covered in cannabis leaf anatomy.
Dry fruit types compared
| Fruit | Seed attachment | Source |
|---|---|---|
| Caryopsis | Fused all over | Virginia MG |
| Achene | One point | Virginia MG |
| Seed parts | Embryo, endosperm, coat | NC State |
| Corn kernel | Caryopsis | Virginia MG |
Sources: Master Gardeners of Northern Virginia, NC State Extension, University of Minnesota Extension.
How to: step by step
- Collect a few grains such as corn kernels.
- Look at the outside of a kernel.
- Soak one overnight.
- Cut it in half lengthwise.
- Find the embryo and the starchy store.
- Compare with a bean seed in a pod.
Troubleshooting
Can’t peel the coat: fused layers. That’s normal.
Grain won’t soften: dry. Soak longer.
Moldy grain: soaked too long. Change the water.
Kind Seed Co shares more seed science notes on the blog.
Sources
- Types of fruit (table), Master Gardeners of Northern Virginia (Virginia Cooperative Extension volunteers)
- Extension Gardener Handbook, chapter 3: Botany, NC State Extension
- Growing sweet corn, University of Minnesota Extension
FAQ
Is a corn kernel a fruit or a seed?
Both, in a sense. The Virginia fruit table lists corn as a caryopsis, a fruit whose seed coat is fused to the fruit wall.
Do all grasses make caryopses?
The Virginia Master Gardeners table calls the caryopsis the fruit of the grass family, Poaceae, with bamboo, cereal, corn and grass as examples.
What is bran?
Extension sources don't define bran. In a caryopsis the outer layer is the seed coat fused to the pericarp.
How is a caryopsis different from an achene?
The Virginia table says an achene is one seeded and attached to the pericarp at a single point, while a caryopsis has the seed coat fused to it all over.
What is inside a grain?
NC State Extension says a seed holds an embryo, an endosperm that stores food and a seed coat around it.
