Plant Categories

This page is provided to assist growers in correctly categorising any competition entries.
It may be slightly slow to load, so please be patient!

Bulb, Corm or Tuber?

The diagrams above are… Left to right Bulb, Bulb (lilium), Corm, Tuber and Rhizome.

The text below, and most of the diagrams above have been extracted from the excellent book by Brian Mathew and Philip Swindells, “The complete book of BULBS Corms, Tubers and Rhizomes” ISBN 0 86438779 2.

What are bulbs, corms, tubers and rhizomes?

Throughout this book the term bulb is used in a general way to describe any plant with a swollen storage system. This general group of plants consists not only of true bulbs but also corms, tubers and rhizomes, each categorised according to its shape and make-up.

Bulbs are remarkable plants, distinguishable by their shape, form, colour, and adaptability. Understanding the differences between each type of bulbous plant makes it easier to plan and maintain a successful garden.
True bulbs, for example daffodils, tulips and lilies, consist of a short basal stem covered with several protective fleshy leaf scales wrapped around the growing point. Some bulbs, such as fritillaries, have a few large scales, while others, like daffodils, have rings of tightly packed scales. The scales are attached to the base of the bulb, known as the basal plate, from which roots grow. Buds develop between the scales and these grow into new bulbs, which then can be separated, cultivated and grown. In most cases, the whole bulb is enclosed within a tunic of scales, and this forms a tough, dry, protective coat.

Corms, which include crocuses, colchicums and gladioli, look like true bulbs but are usually squatter in shape. Consisting primarily of stem tissue, corms are solid inside, whereas true bulbs have regular layers or scales. The outer surface of the corm is covered by a protective fibrous tunic of modified leaves, which are usually thin and scaly, and roots form at the basal plate of the corm.

Tubers are generally bigger than true bulbs and corms. They have swollen, often irregularly shaped, underground stems that grow with the accumulation of food reserves. Like all stems, tubers have nodes or internodes, and buds or eyes form between the non-functioning leaves to produce new shoots and roots. Begonias, anemones and cyclamens are all popularly grown tubers.

Rhizomes, for example some irises and trilliums, are also bulbous plants. They have creeping stems that act as storage organs and they produce leafy shoots, In the majority of cases, the swollen stems spread horizontally below ground, but occasionally, as in the case of the iris, the stems develop near the surface of the soil.

The diagrams above are… Left to right Bulb, Bulb (lilium), Corm, Tuber and Rhizome.

The text below, and most of the diagrams above have been extracted from the excellent book by Brian Mathew and Philip Swindells, “The complete book of BULBS Corms, Tubers and Rhizomes” ISBN 0 86438779 2.

What are bulbs, corms, tubers and rhizomes?

Throughout this book the term bulb is used in a general way to describe any plant with a swollen storage system. This general group of plants consists not only of true bulbs but also corms, tubers and rhizomes, each categorised according to its shape and make-up.

Bulbs are remarkable plants, distinguishable by their shape, form, colour, and adaptability. Understanding the differences between each type of bulbous plant makes it easier to plan and maintain a successful garden.
True bulbs, for example daffodils, tulips and lilies, consist of a short basal stem covered with several protective fleshy leaf scales wrapped around the growing point. Some bulbs, such as fritillaries, have a few large scales, while others, like daffodils, have rings of tightly packed scales. The scales are attached to the base of the bulb, known as the basal plate, from which roots grow. Buds develop between the scales and these grow into new bulbs, which then can be separated, cultivated and grown. In most cases, the whole bulb is enclosed within a tunic of scales, and this forms a tough, dry, protective coat.

Corms, which include crocuses, colchicums and gladioli, look like true bulbs but are usually squatter in shape. Consisting primarily of stem tissue, corms are solid inside, whereas true bulbs have regular layers or scales. The outer surface of the corm is covered by a protective fibrous tunic of modified leaves, which are usually thin and scaly, and roots form at the basal plate of the corm.

Tubers are generally bigger than true bulbs and corms. They have swollen, often irregularly shaped, underground stems that grow with the accumulation of food reserves. Like all stems, tubers have nodes or internodes, and buds or eyes form between the non-functioning leaves to produce new shoots and roots. Begonias, anemones and cyclamens are all popularly grown tubers.

Rhizomes, for example some irises and trilliums, are also bulbous plants. They have creeping stems that act as storage organs and they produce leafy shoots, In the majority of cases, the swollen stems spread horizontally below ground, but occasionally, as in the case of the iris, the stems develop near the surface of the soil.