Is bamboo a tree or a grass?
First, let me give you the answer in 30 seconds.Bamboo belongs to the grass family, the same family as rice and wheat. It has no cambium, the layer that makes a trunk thicker, so it does not grow thicker every year the way trees do. That is a grass-like trait. On the other hand, its stems become hard like wood, and thick ones live for about 20 years. It is a unique plant that cannot simply be called a grass or a tree.
Bamboo is in the grass family
Bamboo is a plant in the grass family, the same family as rice and wheat, and it belongs to a group within it called the bamboo subfamily. The plants of this subfamily that grow in Japan (bamboos and sasa, a kind of small bamboo) are said to number about 130 species. Bamboo has joints, called nodes, because the stems of grass-family plants have nodes. Within the grass family, bamboo stands out because its stems become hard like wood.
Not thickening each year is grass-like
A tree trunk has a part called the cambium, which adds new cells to make the trunk thicker, so it grows a little thicker every year. Bamboo has no cambium, so it does not grow thicker every year like a tree. Research has also confirmed that the base of a bamboo shoot hardly gets any thicker after it comes out of the ground.
Growing at every node makes it fast
In ordinary trees, the "growing points," where cells divide and grow longer, are found only at the tips of the roots and stems. Bamboo has a growing point at every node, so the whole stem shoots up at once. There are records of madake (Japanese timber bamboo) growing 121 cm and moso bamboo growing 119 cm in 1 day (24 hours), and in just a few months it becomes a full-sized bamboo.
Record figures are from "Properties of Bamboo" by Japan's Forestry Agency.
Neither simply a grass nor a tree
On the other hand, bamboo has a hard stem called a culm, which matches the trunk of a tree, and thick ones live for about 20 years. Its underground stems, called rhizomes, spread sideways, and one was recorded growing 5 m in 1 year. Bamboo has both grass-like and tree-like traits, and Japan's Ministry of Agriculture, Forestry and Fisheries describes it as having "a way of life different from both grasses and trees." You cannot decide which it is just by how thick or hard it looks.
Want to know more?
- Bamboo and sasa are told apart not by size, it is said, but by whether the sheaths on the culm fall off naturally as it grows (bamboo) or stay stuck on (sasa).
- Madake and hachiku bamboo are said to flower in 120-year cycles, and madake flowered across Japan from around 1950 to 1960.
- Decorations for Tanabata (the Star Festival) are said to hang on "sasa," but in fact the thin top part of a bamboo culm is used in most cases.
Quick quiz: test yourself
Which plant family does bamboo belong to?
Show the answer
- The pine family
- The grass family
- The palm family
The grass family Bamboo is in the grass family, like rice and wheat. It has no cambium, so it does not grow thicker every year, which is more like a grass.
Bamboo is in the grass family, like rice and wheat. It has no cambium, so it does not grow thicker every year, which is more like a grass.
Next quiz ›Sources
- 竹の性質林野庁 (in Japanese)
- 身近で不思議なタケの生態に迫る！（aff 2021年3月号）農林水産省 (in Japanese)
- Forest Canopy Structures and Mother Bamboo Rhizome Internodes Impact the Appearance Quality of Bamboo Shoots (Forests, 2023)MDPI Forests（Southwest University ほか）
This article was written after checking the sources above as of 2026-10-03. Explanations may change as research progresses. Photo credits are shown below each photo.
