Despite the simplicity of bamboo’s appearance, there’s so much more to explore than meets the eye. From complex rhizome systems below the surface to towering culms upwards of 160 feet tall, bamboo is as unique as it is beautiful.
While bamboo may have the appearance of a tree, it is botanically a type of grass, just a very unique grass. Anatomically speaking, that means it essentially has all of the same physical properties as grass, including rhizomes, shoots, and blades.
Understanding bamboo’s anatomy will help you better identify different types of bamboo and can play an important role in your understanding of its care needs, uses, and growth patterns. We understand that plant anatomy may be intimidating, so we’ve consolidated the most important components of bamboo anatomy into one handy guide!
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Why is understanding bamboo anatomy important?
There are several reasons why you might want to better understand the anatomy of bamboo plants. First, it can help you identify the bamboo species you have in your garden as well as bamboo growing elsewhere. It can also help you purchase the best bamboo for your space and needs.
Unfortunately, plants are commonly misidentified by sellers, so understanding bamboo anatomy can help you distinguish one kind from another. Additionally, some plants have “bamboo” in their name when they’re not true bamboo, such as lucky bamboo or bamboo palm.
Understanding the anatomical structure of bamboo will also help you work through any problems you encounter in the growing process, from root rot to pest infestations. Not only that but understanding the growth patterns and whether a particular bamboo species is invasive can save you a lot of time and money, avoiding a costly mistake!
Bamboo anatomy vs. grass anatomy
With their tremendous height and sturdy bamboo stems, it’s easy to forget that bamboo is not a tree but a grass. Like other genera of grass, bamboo is a member of the Poaceae family. Their anatomy is the clearest giveaway, as they are identical to other grasses from a structural standpoint.
Don’t feel bad if you thought that bamboo was a type of tree. After all, we harvest bamboo culms for building materials, just like we do wood. Anatomically, however, bamboo and trees are very different. Understanding this distinction will help you identify, grow, and manage your bamboo.
A complete guide to bamboo anatomy
The anatomy of bamboo is as complex underground as it is above-ground. Roots transport water and nutrients to other parts of the plant, complex rhizome systems are responsible for the spread of bamboo, and buds eventually become new stalks.
Above ground, we can see new growths in the form of bamboo shoots that eventually become culms, complete with branches and leaves of all shapes, colors, and sizes. While bamboo stalks may have a simple appearance at first glance, there is certainly more going on than meets the eye.
So let’s dive into the anatomy of bamboo by looking at the main components of a bamboo plant, starting down at the roots and moving all the way up to the leaves!
Like most plants, bamboo has roots that absorb water and nutrients from the soil and transport these to other parts of the plant. Bamboo roots typically grow downward and outward into the soil and are relatively easy to distinguish from rhizomes since they are thinner and more delicate.
These secondary roots usually grow about 2-3 feet deep, which is rather shallow given how tall bamboo can get.
Even though you don’t usually see it, the rhizome system is probably the most critical part of bamboo’s survival. Even when the culms have been cut, bamboo can survive if the rhizome system is intact. You might think of rhizomes as roots, but they are anatomically something quite different.
There are two different types of rhizome systems: leptomorph (monopodial) and pachymorph (sympodial). Understanding the difference is fundamental to classifying bamboo as either running or clumping.
Leptomorph rhizome (running bamboo)
Running bamboo is defined by its leptomorph (thin kind) or monopodial (single point) underground rhizome system.
Leptomorph rhizomes are typically thin and long, with shoots/culms branching off at regular intervals and roots that develop along the nodes. You can think of this type of rhizome as an underground stem laid on its side. Then from each rhizome node, there can be new rhizomes branching out.
Pachymorph rhizome (clumping bamboo)
By contrast, clumping bamboo has pachymorph (thick rhizome) or sympodial (feet together) rhizomes that are characterized by their thick, bulbous size and packed-together nature. Pachymorph rhizomes grow outwards from buds on a “mother” rhizome, eventually turning upwards to become new culms.
There’s a significant difference between these types of bamboo. This one stays closer together forming a clump, while the other type sends out new growth far away.
Did you know that some bamboo species have a rhizome system that has characteristics of both clumping and running bamboo? For this type of mixpodial or amphipodial bamboo, the running rhizomes produce clump-like buds from the node. This differs from your typical running bamboo, which will only develop one bud from a single node.
According to some taxonomists, this third classification is potentially unnecessary and confusing, therefore you are unlikely to see bamboo species classified this way. However, understanding this type of rhizome growth may help you identify a particular species of bamboo.
Buds refer to any new growth that exists below the soil that will eventually result in new shoots. These are produced by the rhizomes at the stem base and petiole so they can break through the soil and avoid rotting.
The base of the culm refers to the part of the bamboo culm just below the soil level. The stem base connects the culm to the rhizome and root system and is also where buds will begin to form. The stem base, depending on the species of bamboo, can form up to 10 buds, which we will explore next.
Once bamboo buds emerge from the soil, they officially become shoots. Bamboo shoots are typically pointed like a spear and can be as thin as a pencil or as thick as a human thigh (Moso Bamboo).
Bamboo shoots are edible after cooking, so many people harvest them for eating.
Anatomy of bamboo culms
The bamboo culm or stem is more complex than you might think. From the outside, it looks solid but it’s hollow (except for Solid Stem Bamboo) and has many different anatomical properties. We don’t want to make it too complicated for you. So let’s start at the bottom in order to inspect the anatomy of the bamboo culm.
Culm sheath or leaf sheath
Long thought to be a modified leaf, the bamboo sheath is actually a modified branch, acting as a protective outer layer around new growth. The sheath serves its purpose until new growth has hardened.
The sheath can have different shapes, colors, and textures, and some even have hairs on the tissue. Sheaths eventually become dry and paper-like as culms fully form, and may fall off.
The blade is a leaf-like growth that forms at the tip of the bamboo shoot, similar to a blade of grass. The blade is what gives bamboo shoots their pointy shape.
Bamboo blades come in a variety of shades, sizes, and textures, with some species even having wavy blades! However, they are much smaller compared to the dominant blades on lawn grasses. This is because shorter grasses have to compete for the sun and use blades to get the sunlight. Bamboo will grow taller and therefore have stronger culms.
The ligule is a thin membrane at the apex of the culm or sheath that creates a protective seal from pests and controls water absorption. The ligule will grow on the culm or sheath connecting to the blade and can also appear at the apex of any foliar growth on bamboo plants. Ligule literally means “little tongue,” which is often what this membrane resembles.
Auricles are raised lobes on either side of the ligule. Meaning “small ears,” auricles are an excellent method of identifying different species of bamboo, as some species have auricles while others do not.
In addition to auricles, your bamboo may also have oral setae, which are small, hair-like growths attached to the auricles and ligules. Like auricles, oral setae are only present in some bamboo species.
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Nodes are typically defined as growth points and can be identified by a prominent bump, joint, or “knuckle” on the plant. Some bamboo nodes are barely visible, while others are very distinct bulges in the culms.
Unlike the rest of the bamboo culm, nodes are solid, representing points on the bamboo where new growth can emerge. As your bamboo plant forms branches along the nodes, those branches will also have nodes!
The nodes are important features of bamboo plants as they play a key role in the mechanical properties of bamboo due to the vascular bundles.
The internode refers to the space between the nodes. Together, they form bamboo culm. While often referred to as stems, poles, or stalks, bamboo culms are anatomically the same as grass culms – round stalks that eventually flower.
The sturdy, hollow, and cylindrical culms are likely the part of the bamboo plant you are most familiar with. While most bamboo culms are round, a famous exception is Chimonobambusa quadrangularis, which has square-shaped culms.
The internode length varies by bamboo species and can be an important factor in identifying a bamboo species because some have irregular internodal lengths, and others have very long or short internodes.
Note: Rhizomes and branches also have internodes.
While not present on all bamboo culms, the sulcus groove is a prominent scar that forms on the internode beginning from the branch joint. The term actually stems from medicine, where a sulcus is defined as a fissure separating different parts of an organ, such as the brain or heart.
The sulcus groove does not form on all bamboo species but is particularly prominent on species in the Phyllostachys genus. The sulcus groove helps moisture run down the surface of the culm.
Near the node, you may find the sheath scar that forms around the internodal section of a bamboo culm, where the sheath was initially attached.
Once the culm no longer needs the protection of the sheath, it will dry out and shed but may leave this scar behind. Some bamboo species have very prominent sheath scars, while others do not.
The supernodal ridge is the upper ring on the internode section that can be slightly swollen and pronounced. This nodal ring is an important feature to pay close attention to when identifying certain bamboo species, as it can either be conspicuous or nearly invisible, depending on the type of bamboo you are looking at.
From the node, your bamboo forms branches, usually on alternating sides. Some species can grow multiple branches from a single node. Bamboo branches are typically thinner than the main culm, but similar in appearance as far as color and shape go.
Branches in turn produce foliage leaves. Depending on the species, these leaves may have the same components as sheath, such as ligules and auricles. In contrast to the sheath, the foliage leaves have a very prominent blade since the main function is photosynthesis.
Bamboo leaves can range from needle-shaped to round in shape, and depending on the species they can even be variegated!