Above the Ground
You need to know the names of the major plant parts and have a basic understanding of what they do in order to understand how bamboo grows and understand my articles on growing and maintaining bamboo. This is a two part article on basic morphology. In this article, you will learn about the parts of bamboo that grow above ground. Click on a keyword to see a picture, and click in the picture to close it.
The main stem of a bamboo is called a culm. The culm is the support structure for the branches and leaves, and conatains the main vascular system for the transport of water, nutrients and food. Culms aslo serve as food storage organs. The culm is made up of jointed segments. The joints are called nodes, and the area between nodes is called an internode. The nodes of a bamboo are always solid, and the internodes of most bamboos are hollow. By splitting a bamboo culm lengthwise, you can see the solid plates inside the culm at the nodes, and the hollow internode. The hollow internodes give the stem flexibility, and the plates give the stem strength and keep it from buckling under stress.
Branching occurs at the nodes, on alternate sides of the culm. In the vast majority of bamboos I grow, the branches are smaller than the culms. Successive branches dwindle in size, finally terminating in the foliage leaves. The way the branches are arranged can often help to identify a bamboo. For example, bamboos in the genus Phyllostachys have a similar branch complement containing two secondary branches.
The foliage leaves are the food producing organs. The green part of the leaf is called the blade. The leaf blade is attached to a leaf sheath, which encloses and protects the newest leaf emerging from the growing tip.
The culms also have leaves, but their primary purpose is to protect the new culms in the early stages of growth. Most of the leaf is comprised of a protective sheath with a very small leaf blade, so the whole leaf is often called a “culm sheath”. The sheaths are attached at the nodes, opening on alternate sides of the culm. In the earliest stages of growth, the sheath completely surrounds and protects the new shoot. Later on, the sheath dries up and in most bamboos, eventually falls away. Like the culms, the new growth of every segment of every branch is covered with a protective sheath. These also dry up and eventually fall away.
That’s the very basics… jointed stems, solid nodes, foliage leaves and culm leaves, protective sheath on all stems. To learn about the underground parts of a bamboo plant, read Bamboo Plant Parts II