Bulb

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.

Bulb (disambiguation)

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

Other meanings of bulb are:

See also

Bulb (photography)

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.

History

The term bulb is a reference to old-style pneumatically actuated shutters; squeezing an air bulb would open the shutter, and releasing the bulb would close it. According to the Focal Encyclopedia of Photography:

It is not clear when the term actually originated. The first industrial produced leaf shutters from Voigtländer in Germany in 1890 had two settings: "M" for Moment exposure and "Z" for Zeit (English: time) exposure. The M-setting enabled the adjustable fractions of a second.

With the Z-setting the shutter opened when pressed and closed when it was triggered again. Around 1894 the third setting "B" for Beliebig (meaning beliebige Zeit, English: any time) was added for the shutter of C. A. Steinheil & Söhne in Munich. The B-setting enabled his shutter to stay opened as long as the release was pressed. Bausch & Lomb in Rochester overtook these settings for their popular Unicum shutters in 1898. With the worldwide success of the shutters of Wollensak like the Junior since 1903, most of the other shutter manufacturers in the world overtook the (now international) settings T for time, I for instantaneous. The B setting was kept until today for the familiar bulb behavior that could be achieved by a cable release in the English-speaking world and for Beliebig in Germany.