Perennial Bulbs: What Are Perennial Bulbs?

Perennial bulbs refer to any plant that contains an underground nutrient storage organ. There are actually are many different types of perennial bulbs and it is useful to know the differences between these various forms of perennial bulbs.

First, there are true perennial bulbs. True perennial bulbs are probably what most people think of when they refer to perennial bulbs, and these include the popular perennial bulb types such as tulips and daffodils. These bulbs are made from nascent leaves that are attached together by a flat basal plate. The nascent perennial leaves surround what will be the following season's flower bud. Some true perennial bulbs also have a paper like outer covering around the bulb (example: tulips), while others will have fleshy scales (example: lilies).

Next, there are corms, another form of perennial bulb that looks much like true perennial bulbs, but when they are cut open you will see that inside is a solid stem instead of nascent leaves. Probably one of the most popular perennial bulbs grown from corms are crocuses.

Next, there are tubers. There are two types of tubers: stem tubers and root tubers. Stem tubers are perennial bulbs that have modified stems like crocuses instead of a basal plate or tunic. Probably the best known stem tuber is the potato. Tubers have growth buds on them called eyes that both roots and shoots will sprout from once planted. There are also tuberous roots tubers, that only include the root portion of the plant. Dahlias are a well known form of root tuber.

Finally, we have rhizomes, which are thickened underground stem systems that grow horizontally underground. Rhizomes are a form of perennial bulb that can often spread quickly. An example of a popular rhizome based perennial bulb is the Bearded Iris.

Hopefully these descriptions will help you as you prepare your perennial bulb garden plans. For even more information about perennial bulbs, please return to the Perennial Bulbs Home Page.