How Does a Plant Bulb Differ from a Corm?

Bulbs are complex structures that store nutrients and information.

Gardeners usually use the term "bulb" to refer to all underground plant storage structures that contain the plant's nutrient reserves. In fact, a bulb is just one-fourth of the story.

Geophyte

An underground storage system that contains plant nutrients and encompasses the entire plant life cycle within is actually called a geophyte. The term refers to bulbs, corms, tubers and rhizomes.

Bulbs

Bulbs produce flowers like daffodils, tulips and hyacinths. Bulbs are layered inside and contain a basal plate from which roots grow, fleshy scales for primary storage of nutrient reserves to sustain the developing flower and leaves, a skinlike covering called a tunic, and shoots where buds and flowers develop.

Corms

If a corm were cut open, it would not reveal visible storage rings like the one ones created by layered tissues in bulbs. This is the major feature that distinguishes corms from bulbs. Corms are swollen stem bases that have been modified to become storage tissue. Gladiolus and crocus are examples of corms.

References

• University of Illinois Extension: Bulb Basics
• University of California Cooperative Extension: Bulbs Part II Questions and Answers
• University of Florida UF/IFAS Extension: Bulbs in the Florida Garden