What is a Rhizome?

The field of botany is complex, with many confusing and complicated terms for the plants. One of those unusual terms is a rhizome. But what is a rhizome? Simply put, it's a type of stem that runs beneath the ground, or sometimes even above the ground. The word rhizome comes from the Greek word for root stalk. A rhizome can sprout roots from certain areas on the stem called nodes. When a bud forms on the rhizome, a new shoot will form which grows into a new plant, even though technically it is the same plant.

Some plants that have rhizomes are bamboo, ginger, orchids, Bermuda grass and poison oak. This is why these plants tend to spread quickly and easily, covering a large area of ground. This can be a good thing for landscaping if there is an empty space that needs filling. But, plants with rhizomes can also become out of hand, spreading too fast and becoming troublesome. This is one of the reasons some invasive or exotic species of plant spread so fast, choking out the native plants and sometimes destroying an ecosystem.

Also, plants with rhizomes don't make very good or effective potted plants because the underground stems need room to spread and can become bound up by the pot. The plants that have rhizomes above the ground include ferns and irises. A rhizome helps to spread the plant over a large area, which actually makes it a very efficient and effective plant. However, rhizome plants can very almost impossible to get rid of.

When the rhizome is snipped off or cut by a lawn mower or shovel, it doesn't die off like an ordinary root would. Instead, both parts of the cut rhizome will become new plants. It will be separated from the original plant, but it doesn't matter, it'll still grow, and spread. This is why weeds with rhizomes are so hard to eradicate, even with poison. Crab grass is an excellent example of this. Even if you chemically treat the patch of crab grass, the underground rhizomes will have already spread out in all directions, ready to grow into new crab grass. Digging out a patch of crab grass won't work either. You'd have to find each and every rhizome and find where they went and then destroy them. As you can imagine, that would be pretty much impossible.

But not all rhizomes are bad. In fact, arrowroot, which is a product used in baking or as a thickening agent, is made from the starchy rhizome of the arrowroot plant. Basically, rhizomes are nature's way of propagating the species.