Bulb


Bulb
Shallot bulbs
Amaryllis bulb

A bulb is a short stem with fleshy leaves or leaf bases.[1] The leaves often function as food storage organs during dormancy.

A bulb's leaf bases, known as scales, generally do not support leaves, but contain food reserves to enable the plant to survive adverse 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.[2] 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.[3]

Other types of storage organs (such as corms, rhizomes, and tubers) are sometimes erroneously referred to as bulbs. 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:

Oxalis, in the family Oxalidaceae, is the only dicotyledon genus that produces true bulbs.[4]

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.[2]

Bulbil

Some lilies form small bulbs, called bulbils in their leaf axils. Several members of the onion family, Alliaceae, including Allium sativum (garlic), form bulbils in their flower heads, sometimes as the flowers fade, or even instead of the flowers. The so-called Tree onion (Allium cepa var. proliferum) forms small onions which are large enough for pickling.

Some ferns, such as Hen and Chicken Fern produce new plants at the tips of the fronds' pinnae, which are sometimes referred to as bulbils.

References

  1. ^ Bell, A.D. 1997. Plant form: an illustrated guide to flowering plant morphology. Oxford University Press, Oxford, U.K.
  2. ^ a b Mishra, S.R. (2005). Plant Reproduction. Discovery Publishing House. pp. 120–125. ISBN 9788171419555. http://books.google.com/books?id=giqdNdoJNQsC. 
  3. ^ Ellis, Barbara W. (2001). Bulbs. Houghton Mifflin Harcourt. p. 3. ISBN 9780618068906. http://books.google.com/books?id=HeSW3gkjXFMC. 
  4. ^ Hartmann, Hudson Thomas; Dale E. Kester (2002). Hartmann and Kester's Plant Propagation: Principles and Practices (7 ed.). Prentice Hall. p. 561. ISBN 9780136792352. 

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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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