BULB (bulb). A bulb is a thick, fleshy bud that usually grows underground. In many plants, such as the tiger lily, it grows above ground, in the spot where the leaves branch from the plant stem. Bulbs are of two types: the scaly and the tunicate. The scary type bulb as in most lilies is made up of a short central core inside of thick, fleshy, scale like leaves. The tunicate bulb, such as the onion, has fleshy leaf bases in smooth and continuous layers. If an onion is cut in half, the inside looks like thickened bands or circles of tissue. Roots generally grow from the base of the bulb. The bulb serves as a storage place with enough food and water to supply the plant during winter or a dry period.
The bulb is also a storehouse for new stems, leaves and flowers, after the plant first flowers. In fact, the bulb has in it a new stem and often the beginnings of flowers and leaves as well. These are protected within the bulb by the bulb scales. These scales or leaves are a food storehouse for the plant. The food stored in the bulbs during one season is used for the beginning of the growth of the stem, leaves and flowers during the next season. A number of different kinds of bulbs such as the onion are used for food. Some other examples of the bulb are the lily bulbs, the tulip bulbs, and the hyacinth.