bulb

1. Botany.
   1. A short, modified, underground stem surrounded by usually fleshy modified leaves that contain stored food for the shoot within: an onion bulb; a tulip bulb.
   2. A similar underground stem or root, such as a corm, rhizome, or tuber.
   3. A plant that grows from a bulb.
2. A rounded projection or part: the bulb of a syringe.
3. An incandescent lamp or its glass housing.
4. Anatomy. A rounded dilation or expansion of a canal, vessel, or organ.

[Latin bulbus, from Greek bolbos, bulbous plant.]

For more information on bulb, visit Britannica.com.

In lighting, see lamp bulb, light bulb.

1. a rounded mass or enlargement.
2. medulla oblongata.

• aortic b. — the enlargement of the aorta at its point of origin from the heart.
• auditory b. — the membranous labyrinth and cochlea.
• eye b. — the eyeball.
• gustatory b's — taste buds.
• hair b. — the bulbous expansion at the proximal end of a hair, in which the hair shaft is generated.
• heel b. — the swollen part of the hoof wall and adjacent soft tissue at the back of the hoof characterized by a periople which is wider than at any other part of the hoof.
• Krause's b's — see bulboid corpuscle.
• olfactory b. — see olfactory bulb.
• penile b. — see penile bulb.
• taste b's — taste buds.
• urethral b. — the enlarged proximal part of the corpus spongiosum.
• vestibular b., vestibulovaginal b. — a body consisting of paired masses of erectile tissue, situated one on either side of the vaginal orifice.

A storage organ, usually formed underground. The swollen portion consists mostly of fleshy, food-storing scales attached to a short flat stem. Onions, for example, are bulbs.

For other uses, see Bulb (disambiguation).

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Shallot bulbs

A bulb is an underground vertical shoot that has modified leaves (or thickened leaf bases) that are used as food storage organs by a dormant plant.

A bulb's leaf bases generally do not support leaves, but contain food reserves to enable the plant to survive adverse conditions. The leaf bases may resemble scales, or they may overlap and surround the center of the bulb as with the onion. A modified stem forms the base of the bulb, 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.

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

All plants that form true bulbs are monocotyledons, and include:

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

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 grow offshoots on top of their fronds, which are also referred to as bulbils.

Wild garlic (Allium vineale) bulbils sprouting

Tree onions form clusters of small bulbs instead of flowers

Most flower bulbs require a cold winter frost to bloom perennially. In the southern United States, bulbs species have developed which do not need this cold frost to return year after year and multiply. These bulbs include several narcissus, the French Roman Hyacinth, and a tulip among others.

References

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Dansk (Danish)
n. - pære, elektrisk pære

Nederlands (Dutch)
bol, bloembol, gloeilamp

Français (French)
n. - bulbe, oignon, (Élec) ampoule, (Chim) ballon, cuvette (d'un thermomètre)

Deutsch (German)
n. - Zwiebel, Birne, Glühlampe, (tech.) Glaskolben, Gummiballon

Ελληνική (Greek)
n. - βολβός, γλόμπος, λαμπτήρας

Italiano (Italian)
bulbo, lampadina

Português (Portuguese)
n. - bulbo (m) (Bot.) (Anat.), lâmpada (f) elétrica (Eletr.)

Русский (Russian)
луковица, лампочка

Español (Spanish)
n. - bulbo, cebolla, bombilla, lamparita

Svenska (Swedish)
n. - lök, glödlampa

中文（简体）(Chinese (Simplified))
球茎, 电灯泡

中文（繁體）(Chinese (Traditional))
n. - 球莖, 電燈泡

한국어 (Korean)
n. - 구근, 편도선, 벌브 노출

日本語 (Japanese)
n. - 球根, 電球, 球部

العربيه (Arabic)
‏(الاسم) زجاجه مصباح كهربائي, بصله‏

עברית (Hebrew)
n. - ‮נורת חשמל, בולבוס, פקעת‬

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