bulbtype

Bulb type is a term used in botany and horticulture to describe the form of underground storage organs that many geophytic plants use to survive unfavorable seasons. The classification helps distinguish how plants store energy, reproduce vegetatively, and respond to environmental cues. The most common contrast is between true bulbs and other underground storage organs such as corms, tubers, and rhizomes.

True bulbs are rounded underground structures formed from fleshy leaf bases arranged in concentric layers around a basal plate. They typically have a protective outer covering called a tunic. In horticultural usage, bulbs are described as tunicate if they possess a dry papery tunic; if the outer covering is reduced or absent, the bulb may be referred to as scaly or non-tunicate.

Corms are storage organs that resemble bulbs but are composed of a swollen stem with a tunic rather than layered leaf bases; they store energy in stem tissue and produce shoots from the top. Tubers store energy in swollen roots or stolons, while rhizomes store energy in horizontal underground stems that produce shoots and roots at intervals.

Bulb type influences cultivation and propagation. True bulbs often require well-draining soil, seasonal moisture patterns, and a period of cool dormancy; corms and tubers may tolerate different moisture regimes and transplanting needs. When planning plantings, gardeners use bulb type to determine planting depth, spacing, and post-harvest handling. In catalogs and checklists, bulb type helps group species by growth form and propagation method.

Note that the term is practical and descriptive rather than a formal taxonomic rank; rival sources may differ in precise definitions for tunicate versus non-tunicate and for the boundaries between bulbs, corms, and other storage organs.