bulb

bulb
—bulbed, adj. —bulbless, adj.
/bulb/, n.
1. Bot.
a. a usually subterranean and often globular bud having fleshy leaves emergent at the top and a stem reduced to a flat disk, rooting from the underside, as in the onion and lily.
b. a plant growing from such a bud.
2. any round, enlarged part, esp. at the end of a cylindrical object: the bulb of a thermometer.
3. Elect.
a. the glass housing, in which a partial vacuum has been established, that contains the filament of an incandescent electric lamp.
b. an incandescent or fluorescent electric lamp.
4. Anat. any of various small, bulb-shaped structures or protuberances: olfactory bulb; bulb of urethra.
6. Building Trades. a rounded thickening at the toe of an angle iron or tee.
7. Naut. a cylindrical or spherical prominence at the forefoot of certain vessels.
8. Photog. a shutter setting in which the shutter remains open as long as the shutter release is depressed. Symbol: B
[1560-70; < L bulbus < Gk bolbós onion, bulbous plant]

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In botany, the resting stage of certain seed plants, particularly perennial monocotyledons (see cotyledon), consisting of a relatively large, usually globe-shaped, underground bud with membranous or fleshy overlapping leaves arising from a short stem.

The fleshy leaves function as food reserves that enable a plant to lie dormant when water is unavailable (during winter or drought) and to resume active growth when favourable conditions again prevail. There are two main types of bulbs. One, typified by the onion, has a thin papery covering protecting its fleshy leaves. The other, the scaly bulb, as seen in true lilies, has naked storage leaves, with no papery covering, making the bulb appear to consist of angular scales. Bulbs enable many common ornamentals, such as the narcissus, tulip, and hyacinth, to flower rapidly in early spring when growing conditions are favourable. Other bulb-producing plants bloom in the summer (e.g., lilies) or fall (e.g., the autumn crocus). The solid corms of the crocus and gladiolus and the elongated rhizomes of some irises are not bulbs.

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▪ plant anatomy
      in botany, structure that is the resting stage of certain seed plants, particularly perennial monocotyledons. A bulb consists of a relatively large, usually globe-shaped, underground bud with membraneous or fleshy overlapping leaves arising from a short stem. An onion is a commonly known bulb. A bulb's fleshy leaves—which in some species are actually expanded leaf bases—function as food reserves that enable a plant to lie dormant when water is unavailable (during winter or drought) and resume its active growth when favourable conditions again prevail. There are two main types of bulbs. One type, typified by the onion, has a thin papery covering protecting its fleshy leaves. The other type, the scaly bulb, as seen in true lilies, has naked storage leaves, unprotected by any papery covering, that make the bulb appear to consist of a series of angular scales. Bulbs can vary in size from insignificant pea-sized structures to those of large crinums (crinum lilies), the individual bulbs of which may weigh more than 15 pounds (7 kg).

 Bulbs enable many common garden ornamentals, such as the narcissus, tulip, and hyacinth, to produce their flowers rapidly, almost precociously, in early spring when growing conditions are favourable. Other bulb-producing plants, such as the lilies, flower in the summer, while a few, such as the meadow saffron, bloom in the fall. Bulb-producing species are especially abundant in the lily and amaryllis families. A few bulb-producing species are of economic importance to humans owing to the taste and nutritive value of their fleshy leaves. Included among such species are the onion and its relatives, the shallot, garlic, and leek. Some bulbs contain poisonous compounds, such as the red squill (Urginea), the bulbs of which are the source of a highly effective rat poison.

      In horticulture the term bulb is incorrectly applied to a number of botanical structures that have a similar food-storing function. Among these are the solid corms of the crocus and gladiolus and the elongated rhizome of some irises.

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Universalium. 2010.

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Synonyms:
(like those of the onion and the tulip) /


Look at other dictionaries:

  • bulb — bulb …   Dictionnaire des rimes

  • bulb — BULB, bulbi, s.m. 1. Tulpină (subterană) a unor plante, alcătuită din frunze în formă de tunici sau solzi suprapuşi (în care se depun substanţe de rezervă), cu un înveliş membranos uscat. 2. (În sintagmele) Bulb pilos = partea terminală, umflată …   Dicționar Român

  • 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 …   The Collaborative International Dictionary of English

  • bulb — [bulb] n. [ME < L bulbus < Gr bolbos] 1. an underground bud that sends down roots and consists of a very short stem covered with leafy scales or layers, as in a lily, onion or hyacinth 2. a corm, tuber, or tuberous root resembling a bulb,… …   English World dictionary

  • bulb — [bʌlb] n ↑filament, ↑thread [Date: 1500 1600; : Latin; Origin: bulbus, from Greek bolbos plant with a bulb ] 1.) the glass part of an electric light, that the light shines from = ↑light bulb ▪ a 100 watt bulb …   Dictionary of contemporary English

  • bulb — (n.) 1560s, an onion, from M.Fr. bulbe, from L. bulbus bulb, onion, from Gk. bolbos plant with round swelling on underground stem. Expanded by 1800 to swelling in a glass tube (thermometer bulb, light bulb, etc.) …   Etymology dictionary

  • bulb — bulb; bulb·less; bulb·let; pseu·do·bulb; …   English syllables

  • Bulb — Bulb, v. i. To take the shape of a bulb; to swell. [1913 Webster] …   The Collaborative International Dictionary of English

  • bulb — [ bʌlb ] noun count * 1. ) the part of a plant that is shaped like an onion from which a flower grows. You plant bulbs in the ground: daffodil bulbs 2. ) a LIGHT BULB …   Usage of the words and phrases in modern English

  • bulb — ► NOUN 1) a rounded underground storage organ present in some plants, consisting of a short stem surrounded by fleshy leaf bases. 2) a light bulb. 3) an expanded or rounded part at the end of something. ORIGIN Greek bolbos onion, bulbous root …   English terms dictionary

  • bulb — Mot Monosíl·lab Nom masculí …   Diccionari Català-Català

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