Bulb
In botany, a
bulb is a short stem with fleshy leaves or leaf bases that function as food storage organs during dormancy. 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 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 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.