Each eye contains a cluster of buds. A rhizome is a specialized stem which grows horizontally at or just below the soil surface. They act as a storage organ and means of propagation in some plants and are similar to stolons. Johnsongrass is a hated weed principally because of the spreading capability of its rhizomes. If you cut through the center of a tulip or daffodil bulb in November, you can see all the flower parts in miniature within the bulb.
Many bulbs require a period of low-temperature exposure before they begin to send up the new plant.
Both the temperature and length of this treatment are of critical importance to commercial growers who force bulbs for holidays. Corms are not the same as bulbs. They have shapes similar to bulbs, but do not contain fleshy scales. A corm is a solid, swollen stem whose scales have been reduced to a dry, leaflike covering. Some plants produce a modified stem that is referred to as a tuberous stem.