Although crocus look a lot like bulbs and are treated the same way as bulbs, they’re not true bulbs. True bulbs are buds surrounded by immature leaves and stem tissue. Examples of bulbs include tulips, onions, and lilies. If you cut open a true bulb, you can see the layers of tissues. Crocus are corms, which are similar to true bulbs but aren’t made up of layers of tissue. Also, individual corms are replaced by younger, stronger corms each year. Another example of plants that grow from corms is gladiolus. Tubers, such as caladium and potato, are sometimes considered bulbs. Like corms, they’re not made up of layers or rings of tissue. Tuberous roots are different again. Although they resemble tubers, they’re made up of a different kind of tissue and are more closely related to roots. Examples of plants having tuberous roots are dahlia and tuberous begonia.