The Spruce / Dennis Madamba
Certain plants have a swollen, underground plant stem called a “corm.”
But when gardeners are speaking casually, they often fail to make a distinction between them.
Instead, they loosely call all of these swollen, underground plant parts “bulbs.”
The Spruce / Dennis Madamba
But if you want to lump them all together using one word, the correct umbrella term is geophytes.
“Geophyte” is made up of the Greek words for earth and plant.
It includes perennial plants with underground food storage organs.
The crocus(Crocus vernus) is an example of a small plant that grows from a corm.
Its rounded corm measures roughly 1 inch in diameter.
A larger plant that springs from a corm is the snake lily (Amorphophallus konjac).
But true bulbs are divided into layers (think of an onion), including a papery outer layer.
A bulb is comprised of a plant’s stems and leaves.
The bottom of the bulb is a compacted stem, with roots growing from it.
Corms are not divided in this way; rather, they are solid units.
What Are Tubers and Rhizomes?
So what is the difference between tubers and corms?
Tubers are formed from a stem or root.
They store nutrients that allow the plant to grow the following season.
Buds sprout from tubers (think of the “eyes” on a potato).
Shoots grow upwards from many different places on the tuber.
An example landscape plants that grows from tubers are theDahliaand begonias.
Tubers, like potatoes, multiply underground.
Still, other plants grow fromrhizomes.
They often appear as nothing more than roots.
Buds form at different parts along the rhizome, not just the tip.
Corms have a solid center and a scaly texture.
You will find fibrous roots growing from the bottom of the corm.
None of the common vegetables have corms (potatoes are tubers).
Chinese water chestnuts (Eleocharis dulcis) and taro (Colocasia esculenta) are edibles with corms.
Yes, you cam use corms to propagate plants.
