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bulb, thickened, fleshy plant bud, usually formed under the surface of the soil, which carries the plant over from one blooming season to another. It may have many fleshy layers (as in the onion and hyacinth) or thin dry scales (as in some lilies)—both of which are highly modified leaves. Many popular outdoor and house plants, such as the tulip and the narcissus, are grown from bulbs, often out of their usual flowering season by forcing (i.e., by exposing them to a cold treatment). Not true bulbs, but often so called, are the corm of the crocus and the gladiolus, the tuber of the dahlia and the potato, and the rhizome of certain irises. All such organs are specialized subterranean stems serving for food and water storage and asexual reproduction.


See J. E. Bryan, Bulbs (1989).

The Columbia Electronic Encyclopedia™ Copyright © 2022, Columbia University Press. Licensed from Columbia University Press. All rights reserved.
The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.



a modified, usually subterranean shoot with a greatly shortened stem and fleshy scalelike leaves.

Bulbs store water and nutritive substances (primarily sugars); they are also a means of vegetative renewal and reproduction. In some plant species, bulblets develop in the inflorescences (onions and meadow grasses) or in the leaf axils of aboveground shoots (lilies and toothworts). Bulbs can function as storage organs for approximately one year (annual bulbs of tulips, onions, and fritillary) or longer (perennial bulbs of narcissus, snowdrop, and hyacinth). After their nutrients have been used, dry scales form protective outer coverings. Scaly bulbs have narrow scales that touch the bulb only at their bases (lilies); tunicated bulbs have broad enwrapping scales (onions).

According to the manner of growth, two types of bulbs are distinguished. Monopodial, or intermediate, bulbs renew themselves at the expense of the terminal bud of the bulb stem (snow-drop, narcissus, and belladonna lily). In plants with sympodial, or determinate, bulbs, the inflorescence and aboveground parts develop from the terminal bud, but the bulb regenerates at the expense of the bud located in the axil of a scale (tulips, onions, and hyacinths). In sympodial bulbs the mother bulb is replaced annually by daughter bulbs. If not one but two or more buds are active, the bulb reproduces vegetatively. In garlic plants several cloves form in the axils of the bulb scales and are arranged in a row, thus constituting complex bulbs.


The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.


A short, subterranean stem with many overlapping fleshy leaf bases or scales, such as in the onion and tulip.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.


In lighting, see lamp bulb, light bulb.
McGraw-Hill Dictionary of Architecture and Construction. Copyright © 2003 by McGraw-Hill Companies, Inc.


1. a rounded organ of vegetative reproduction in plants such as the tulip and onion: a flattened stem bearing a central shoot surrounded by fleshy nutritive inner leaves and thin brown outer leaves
2. a plant, such as a hyacinth or daffodil, that grows from a bulb
3. See light bulb
4. a rounded part of an instrument such as a syringe or thermometer
5. Anatomy a rounded expansion of a cylindrical organ or part, such as the medulla oblongata
6. Nautical a bulbous protuberance at the forefoot of a ship to reduce turbulence
Collins Discovery Encyclopedia, 1st edition © HarperCollins Publishers 2005
References in periodicals archive ?
They joined the company full-time in the early 1990s and now own and operate one of the largest wholesale flower bulb distributors in the United States, as well as the European subsidiary Van Zyverden, B.V.
Lucas adds: 'Indoor flower bulbs look great anywhere in the home - from simple Christmas table decorations and gifts to funky decorations for every room for a New Year party.
However, planting flower bulbs can also be done at home and is the simplest way to get the whole family hooked on gardening.
For more information on this and other flower bulb trends and style ideas, log onto The Netherlands Flower Bulb Information.
ADVICE - Miek Stap, from the Netherlands Flower Bulb Information Centre.
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McClure & Zimmerman, PO Box 368, Friesland, WI 53935 styles itself "quality flower bulb brokers" for the "dedicated bulb enthusiast." The depth and range of bulbs meets and sometimes exceeds listings found in other catalogs.
Ward has teamed up with the Netherlands Flower Bulb Information Centre to create six contemporary ideas for using spring bulbs in containers.
Roozen, technical director of the Netherlands Flower Bulb Information Service, is clearly a dessert man.
According to the International Flower Bulb Information Centre, the emphasis for spring 2002 is on a breezy colour palette that combines fresh, bright hues with greyed pastels.
WE have 10 parcels of summerflowering bulbs worth around pounds 25 each to give away courtesy of the Netherlands Flower Bulb Information Centre.
The delicate-looking Gladiolus callianthus Murielae, originally from central Africa, has been crowned the 2008 Summer Bulb of the Year at the annual event hosted by The Netherlands Flower Bulb Information Centre.