Bulbs are the thickened underground storage organ of the group of perennials that include tulips and daffodils.  A flower bulb is really an underground storehouse and flower factory. Within the bulb is just about everything the plant will need to sprout and flower at the appropriate time. Split a bulb in half and you will see this clearly.

In the basal center portion of the bulb are the leaves cradling a baby bud. (In many species, this bud already has the appearance of a flower while still in the bulb!) Surrounding the bud is a white, meaty substance called the scales. In true bulbs, it is these scales which contain all the food the bulb will need to flower and thrive. Anchoring the scales and the floral stalk which holds the bud is the basal plate. This plate at the bottom of the bulb also holds the roots of the plant. The entire package is protected by a thin outer skin called the tunic.

All this remarkable organism needs from humans is to be placed in the ground at the appropriate season of the year, given a liberal drink of water and then left alone. The bulb does the rest!  Source: Bulb.com