Under the Soil
In this article, you will learn about two different types of rhizome, leptomorph and pachymorph. You’ll also learn about about the roots, which are not rhizomes. You can click on a keyword to see a picture, then click in the picture to close it.
Bamboos have underground stems called rhizomes, which transport water and nutrients, store food, and along with the roots, anchor the plant to the soil. Leptomorph rhizomes grow laterally near the soil surface, and are capable of very rapid growth. This is an exposed leptomorph rhizome of Incense Bamboo that grew about thirteen feet in a single growing season. Leptomorph rhizomes are very similar to culms and branches, having nodes and internodes, as well as a sheath that protects each segment. Instead of branches, the buds occurring at the nodes will either grow into another rhizome, or grow into a culm (a newly developing culm is referred to as a shoot). Along with culm and rhizome buds, root buds also form at rhizome nodes, which develop into anchor and feeder roots; the larger roots are the anchoring roots, and the little fibrous roots absorb water and nutrients from the soil. Larger bamboos also have anchoring roots at the base of the culm, which you can see in the picture below of a developing shoot.
In contrast to a leptomorph rhizome, a pachymorph rhizome turns upward and grows into a culm. New rhizome buds form on the rhizome neck at the base of the culm, which in turn, grow upward into a new culm. The picture below shows all three of these: rhizome neck, new rhizome bud, and new culm
Some key differences between the two rhizomes you should remember are: leptomorph rhizomes can grow many feet over the growing season, and have buds along their length that will grow into new rhizomes or culms. Pachymorph rhizomes will, each and every one, grow into a culm. Can you guess which of these rhizome types correspond with the terms “running” and “clumping”? For more information on this topic, read my article on “Runners vs. Clumpers“.