What is "bulb"

Bulb \Bulb\ (b[u^]lb), n. [L. bulbus, Gr. bolbo`s: cf. F. bulbe.]

1. (Bot.) A spheroidal body growing from a plant either above or below the ground (usually below), which is strictly a bud, consisting of a cluster of partially developed leaves, and producing, as it grows, a stem above, and roots below, as in the onion, tulip, etc. It differs from a corm in not being solid.

2. (Anat.) A name given to some parts that resemble in shape certain bulbous roots; as, the bulb of the aort

   1. Bulb of the eye, the eyeball.

      Bulb of a hair, the ``root,'' or part whence the hair originates.

      Bulb of the spinal cord, the medulla oblongata, often called simply bul

   2. Bulb of a tooth, the vascular and nervous papilla contained in the cavity of the tooth.

3. An expansion or protuberance on a stem or tube, as the bulb of a thermometer, which may be of any form, as spherical, cylindrical, curved, etc.
   --Tomlinson.

   3. a light bulb.

Bulb \Bulb\, v. i. To take the shape of a bulb; to swell.

1560s, "an onion," from Middle French bulbe (15c.), from Latin bulbus "bulb, bulbous root, onion," from Greek bolbos "plant with round swelling on underground stem." Expanded by 1800 to "swelling in a glass tube" (thermometer bulb, light bulb, etc.).

n. 1 Any solid object rounded at one end and tapering on the other, possibly attached to a larger object at the tapered end. 2 A light bulb. 3 The bulb-shaped root portion of a plant such as a tulip, from which the rest of the plant may be regrown. 4 (context nautical English) a bulbous protuberance at the forefoot of certain vessels to reduce turbulence. vb. (context intransitive English) To take the shape of a bulb; to swell.

1. n. a modified bud consisting of a thickened globular underground stem serving as a reproductive structure

2. electric lamp consisting of a glass bulb containing a wire filament (usually tungsten) that emits light when heated [syn: light bulb, lightbulb, incandescent lamp, electric light, electric-light bulb]

3. a rounded part of a cylindrical instrument (usually at one end); "the bulb of a syringe"

4. lower or hindmost part of the brain; continuous with spinal cord; (`bulb' is an old term for medulla oblongata); "the medulla oblongata is the most vital part of the brain because it contains centers controlling breathing and heart functioning" [syn: medulla oblongata, medulla]

5. a rounded dilation or expansion in a canal or vessel or organ

Bulb, abbreviated B, is a shutter speed setting on an adjustable camera that allows long exposure times under the direct control of the photographer. With this setting, the shutter simply stays open as long as the shutter button remains depressed. An alternative setting common on film cameras is Time, abbreviated T, where the button is pressed once to open the shutter and again to close it.

A bulbous plant is one that possesses a bulb. Bulb may refer to

• Bulb (in strict botanical use), a storage organ of a plant made up of fleshy leaf bases
• Ornamental bulbous plant (in gardening or horticulture), any one of a number of different kinds of underground or near ground storage organs which can be dried and from which an ornamental plant can be grown

Other meanings of bulb are:

• Light bulb, a source of electric lighting
• Flashbulb, a bright, rapid light bulb
• Bulb (photography), a shutter setting
• Bulbous bow, a protruding bulb at the bow below the waterline
• Bulb keel, a term in naval architecture
• Bulb Records, a record label
• Bulbs (song), a 1974 song by Van Morrison
• Bulb, of brain, a historical term referring to the medulla oblongata
• BULB Act, a U.S. House bill sponsored by Rep. Joe Barton and others in 2011
• Bulb, the solo project of guitarist Misha Mansoor
• As an abbreviation, "Bulb" is short for the orchid genus Bulbophyllum.

In botany, a bulb is a short stem with fleshy leaves or leaf bases that function as food storage organs during dormancy. (In gardening, plants with other kinds of storage organ are also called " ornamental bulbous plants" or just "bulbs".)

A bulb's leaf bases, also known as scales, generally do not support leaves, but contain food reserves to enable the plant to survive adverse weather conditions. At the center of the bulb is a vegetative growing point or an unexpanded flowering shoot. The base is formed by a stem, and plant growth occurs from this basal plate. Roots emerge from the underside of the base, and new stems and leaves from the upper side. Tunicate bulbs have dry, membranous outer scales that protect the continuous lamina of fleshy scales. Species in the genera Allium, Hippeastrum, Narcissus, and Tulipa all have tunicate bulbs. Non-tunicate bulbs, such as Lilium and Fritillaria species, lack the protective tunic and have looser scales.

Other types of storage organs (such as corms, rhizomes, and tubers) are sometimes referred to as bulbs, although as the term is used in botany, they are not. The technical term for plants that form underground storage organs, including bulbs as well as tubers and corms, is geophyte. Some epiphytic orchids (family Orchidaceae) form above-ground storage organs called pseudobulbs, that superficially resemble bulbs.

Nearly all plants that form true bulbs are monocotyledons, and include:

• Amaryllis, Crinum, Hippeastrum, Narcissus, and several other members of the amaryllis family Amaryllidaceae. This includes onion, garlic, and other alliums, members of the Amaryllid subfamily Allioideae.
• Lily, tulip, and many other members of the lily family Liliaceae.
• Two groups of Iris species, family Iridaceae: subgenus Xiphium (the "Dutch" irises) and subgenus Hermodactyloides (the miniature "rock garden" irises).

Oxalis, in the family Oxalidaceae, is the only dicotyledon genus that produces true bulbs.

Bulbous plant species cycle through vegetative and reproductive growth stages; the bulb grows to flowering size during the vegetative stage and the plant flowers during the reproductive stage. Certain environmental conditions are needed to trigger the transition from one stage to the next, such as the shift from a cold winter to spring. Once the flowering period is over, the plant enters a foliage period of about six weeks during which time the plant absorbs nutrients from the soil and energy from the sun for setting flowers for the next year. Bulbs dug up before the foliage period is completed will not bloom the following year but then should flower normally in subsequent years.

After the foliage period is completed, bulbs may be dug up for replanting elsewhere. Any surface moisture should be dried, then the bulbs may be stored up to about 4 months for a fall planting. Storing them much longer than that may cause the bulbs to dry out inside and become nonviable.