Everyone loves bulbs! They’re often one of the first signs of spring, and they make fantastic additions to a yard (and in some cases, a vase). There are other bulbous plants that aren’t considered “true bulbs,” although we tend to think of them as such. These bulb impersonators are actually stem and root parts. Known as tubers, tuberous roots, corms and rhizomes, these plants can also bring forth glorious blooms in your garden.

Caladiums tuber

Caladiums are a tuber, like a potato.

Photo Credit: Jennifer Manning

Gladiolus corm

Also grown as a dramatic cutflower, gladiolus is an example of a corm.

Photo Credit: Jennifer Manning

Iris rhizome

Notice the lateral rhizome roots of the Iris.

Photo Credit: Jennifer Manning

True Bulbs

A true bulb has a fully formed plant within the bulb. If you were to slice open a tulip bulb vertically, for example, you’d see a small baby tulip with flowers, stems, leaves and roots! Some other examples of true bulbs are the daffodil, lily, hyacinth and amaryllis.

Tubers

Everyone knows that potatoes have eyes. In fact, potato eyes are really buds that are capable of producing both roots and shoots. The potato is actually a modified stem called a tuber. Ornamental plants, such as caladiums, cyclamen and anemone, are also tubers.

Tuberous Roots

Did you realize that the white potato and the sweet potato are actually different plant parts? While the white potato is a “stem,” the sweet potato is a modified root. Called a tuberous root, this is a swollen root, not to be confused with a tuber. Fibrous roots develop and take in the moisture and nutrients needed to initiate new growth buds at the base of the old stem. In addition to sweet potatoes, begonia and dahlia are ornamental examples of tuberous roots.

Corms

The crocus, which is often the first spot of color to pop up in spring, grows from a modified stem called a corm. Corms are typically white with a chalk-like feel. They’re covered with papery fringes similar to the tunicate of a bulb. (Remember, a corm is not a bulb – it’s an impostor.) The “Mother Corm” produces cormels, which come back each year. Gladiolus is another corm commonly considered a bulb.

Rhizomes

The iris is a favorite plant of many, but most believe the plant is a bulb, when it’s actually an underground stem called a rhizome. Rhizomes grow horizontally underground, producing buds that sprout and grow aboveground, generating new plants. Cannas and agapanthus are other well-known rhizomes.

There’s a bulb impersonator out there for everyone. The primary purpose of understanding these different plant parts that support bulbous plants is to learn appropriate ways to divide and propagate these plants. As these underground growers continue to generate year after year, it may be necessary to dig them up and move some to a different location or share with a friend so that the crowded bed will have more room to produce better-quality flowers.

Hopefully by learning some of these basic types, you’ll be able to determine what you want to add to your garden and how to manage it. These plants offer long-lasting beauty in the garden and endless enjoyment for you. So have fun and experiment with bulbs and bulb impersonators!