Like so many things in horticulture, the term "bulb" has taken on all kinds of meanings. Many plant tissues are incorrectly called bulbs including corms, tubers, tuberous roots or storage roots.

A true bulb is a swollen underground bud formed from fleshy scales or leaf bases which acts as a storage unit to enable various plants to rest in a dormant state during part of the year. Bulbs include tulips, daffodils, lilies (not daylilies) and alliums (ornamental onions) among others.

Our index of commonly grown "bulbs" contains many of those used in the home landscape in the temperate regions of North America.