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Difference Between Corm and Bulb

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Stem Modification and Characteristics of Corm and Bulb

In order to understand the difference between Corm and Bulb, one must be aware of the stem and its modifications. Then one can explain corm and bulb.

Meaning of Stem Modification

The plumule of the germination seed gives rise to stems. It has fruits, flowers, leaves, and so on. Nodes and internodes are a stem's defining characteristics. The stem's primary duties include supporting other plant components and facilitating the movement of nutrients, minerals, and water. Many plants have modified stems that can carry out a variety of tasks, including photosynthesis, support, storage, protection, propagation, and perennation. Adaptation and survival are improved through modifications.

Types of Stem Modification

Aerial, subaerial, or underground alterations to stems can occur in various plants. They have been changed to carry out additional tasks that aren't typically done by the stem. Three categories of modified stems are present:

  • Aerial: Tendrils, Thorn, Bulbils, Cladode, Phylloclade 

  • Underground: Rhizome, Bulb, Corm, Tuber 

  • Subaerial: Runner, Sucker, Offsets

Last updated date: 28th Sep 2023
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What is Corm and Bulb?


A corm, also known as a bulbotuber, is a small, vertical, swelling subterranean plant stem that certain plants employ as a storage organ to withstand winter or other harsh circumstances such as summer drought and heat (perennation). Similar to the terms tuberous and bulbous, which refer to plants that develop from tubers and bulbs respectively, the word cormous is used to describe plants that grow from corms.

Structure of Corm

A corm is made up of one or more internodes with at least one growth point and protecting leaves that have typically been transformed into skins or tunics. Dead petiole sheaths(remains of leaves generated in past years) form the tunic of a corm. They serve as a covering, guarding the corm against pests, animals that dig, floods, and water loss. certain species' tunics are thin, dry, and papery, at least in young plants. However, in certain families, like the Iridaceae, a mature corm's tunic may provide a powerful defense.


A bulb is a small stem with fleshy leaves or leaf bases that serve as food storage organs while an organism is dormant. The vegetative and reproductive development stages of bulbous plant species alternate; during the vegetative stage, the bulb reaches blooming size, and during the reproductive stage, the plant blooms. The change from one stage to the next is triggered by certain environmental factors, such as the transition from frigid winter to spring.

Structure of Bulb

Although the leaf bases of bulbs, also known as scales, often do not support leaves, they do have food reserves that help the plant withstand harsh environmental conditions. An unexpanded blooming stem or a vegetative growth point might be found in the bulb's center. A decreased stem serves as the base, and it is from this basal plate that the plant grows. New stems and leaves grow from the top side of the base, while roots appear from the lower side. The continuous lamina of fleshy scales on tunicate bulbs is shielded by dry, membranous outer scales.

Corm and Bulb Difference 

The table presented below highlights the main differences between Corm and Bulb.







Structure-wise, bulbs are composed of slender stems with fleshy leaves or leaf bases.

Underground storage organs known as corms have a spherical shape and are made up of a swelling stem base that is covered in scale leaves.



Scales, which are remodeled leaves, are found in bulbs.

Corms are modified stems that are smooth.


Part involved

Nutrient-storing bulbs are altered leaves.

Swollen stem bases are known as corms.



A bulb has an approximately spherical or pyriform shape.

It might be elongated, vertically compressed, or spherical.



A bulb bears its buds inside.

A corm bears its buds externally.



A subterranean shoot has condensed into the bulb.

A stem that lies underground forms a corm.



The leaf bases serve as food storage.

The stem has food storage.



Bulbs include things like tulips, hyacinths, allium, onions, and daffodils.

Corms include plants like gladiolus, freesia, and crocus.


The major distinction between bulbs, corms, tubers, and rhizomes is that bulbs are modified leaves that store nutrients, whereas corms, tubers, and rhizomes are swollen stem bases and thick subterranean stems, respectively. For instance, gladiolus, freesia, and crocus grow corms; potatoes generate tubers; iris, lily-of-the-valley, canna, and calla lilies create rhizomes. Hyacinths, allium, onions, and tulips also develop bulbs. In this way, this article aims to explain corm and bulb.

FAQs on Difference Between Corm and Bulb

1. What are the characteristics of Corm?

Modified stems with a tunic are called corms. They are a special kind of stem tissue that was developed to retain nutrients. Flattened but spherical, corms are. Their reticulate or netted tunic is made of fibers. Rings can smooth out some tunics. Their name is Annulate. A corm may have numerous growth points, which are visible as bumps or nodes, and the basal plate is located at the bottom of the corm. Gladiolus, freesia, and crocus are a few examples of plants that produce corms.

2. Which plants produce Corm and Bulb?

Geophytes are plants that produce subterranean storage organs, such as tubers, corms, and bulbs. Some epiphytic orchids (Orchidaceae family) produce pseudobulbs, which are above-ground storage organs that first resemble bulbs. Monocotyledons make up the majority of plants that produce real bulbs, and they include Amaryllis, Crinum, Hippeastrum, Narcissus, and a number of other plants of the Amaryllidaceae family. Included in this are alliums, such as onion, garlic, and other members of the Amaryllid subfamily Allioideae.

3. What is Corm and Bulb?

The structurally short stem with fleshy leaves or leaf bases that serve as food storage organs during dormancy is referred to as the bulb. Corms are circular subterranean storage organs that are found in plants and have a base that is inflated and covered in scale leaves. Rhizomes are continually developing horizontal subterranean stems that periodically send forth lateral shoots and adventitious roots, whereas tubers are a much thicker underground portion of a stem.  While corms are smooth modified stems, bulbs feature scales, which are modified leaves.