bulb

Bulb is a term with two common meanings: a botanical storage organ in certain flowering plants and a glass envelope used in electric lighting. In botany, a true bulb is an underground, rounded organ that stores nutrients and supports perennating growth. It consists of a short stem with fleshy, leaf-like structures called scales arranged around a basal plate from which roots emerge. A papery outer covering, the tunic, often helps protect the bulb during storage. Examples of edible or ornamental bulbs include the onion (Allium cepa), garlic (Allium sativum), shallot (Allium ascalonicum), and many flowering species such as tulips (Tulipa spp.). Bulbs differ from similar structures: corms are solid stems with a tunic, while tubers are swollen storage organs formed on stolons or roots.

Morphology and life history: Bulbs store carbohydrates and other reserves to fuel shoot growth in favorable seasons. Many species go dormant during adverse periods and require specific cues, such as cooling, to resume growth and flowering. Reproduction often occurs vegetatively through offsets or bulblets, enabling clonal propagation.

Culinary and horticultural significance: The term “bulb” commonly refers to edible crops used as vegetables or flavoring, as well as to ornamental bulbs grown for seasonal flowers in gardens and landscapes. Etymology traces to the Latin bulbus, meaning a swollen rounded structure.

Electrical bulb: In lighting, a bulb denotes a glass envelope that contains a filament and either a vacuum or inert gas. Electric bulbs operate by passing current through a filament, which heats to incandescence. Early carbon filaments were replaced by tungsten; modern lighting also includes halogen and solid-state sources such as LEDs. The bulb has evolved from a basic incandescent device to a family of energy-efficient lighting technologies.