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Reasons Why Bamboo Is a Grass Not a Tree

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Bamboos are considered evergreen grasses despite some of the species achieving sizes so big they are often confused with trees by many people. 

If you want to go more specific with the botanical classification then you can say that bamboos are evergreen perennial flowering plants in the subfamily Bambusoideae of the grass family Poaceae

Why people confuse bamboo with trees

Bamboo is often confused for a tree because some of the species grow really tall and pretty wide and even make “bamboo forests”. Bamboo is the largest and tallest of the grasses. 

So it is no wonder that when you see a large Moso bamboo you don`t imagine it is related to the lawn grass that is short and green.

Some species may even be marketed as bamboo trees because of how they are used. For example when bamboo is used in making various kitchen products like bowls spoons, and chopsticks it looks very similar to wood.

Bamboo tea kit by Alan Levine
Bamboo tea kit – looks quite woody, right?

The same is true when bamboo is used in home decor – a bamboo floor definitely has similarities in looks with hardwood floors. 

What are the characteristics of grasses

Poaceae is a large family of plants commonly known as grasses. It includes several types of grasses like the cereal grasses, bamboos and the grasses of natural grassland and cultivated lawns and pasture.

Grasses can be both annual and perennial plants.

So let’s see what are some of the most typical characteristics of grasses.

The stems of grasses are called culms and these culms are usually cylindrical (with some exceptions) and hollow except at the nodes(joints) that separate the hollow parts. The nodes are also where the leaves are attached. The lower part of each leaf encloses the culm, forming a leaf-sheath.

Grasses are colony plants, and the existing grasses help produce new growth through the root system. 

Grasses grow in size not by cell division but by elongation

All plants photosynthesize but there are actually different types of photosynthesis. All grasses share the same way of photosynthesizing which is known as C4 carbon fixation. 

What are the characteristics of bamboo to be considered as grass?

Bamboo is a colony plant like all grasses. It uses energy from existing bamboos to increase the root mass and produce new shoots. The new plants will also develop in the same way. This is the main way bamboo reproduces.

Sometimes it does go into flower and produce seeds but this is not the main way of reproducing as it is for many other plants. I wrote a post about the way bamboos reproduce a while ago. It`s really fascinating, you can check it out here.

There are 2  main types of bamboo “colonies” – running and clumping. However, there are some differences among species as well as some mixed types. 

The new culms shoot up from the underground rhizomes and stretch in size vertically. It is a quick process that does not involve cell division as all the cells are already made before the bamboo shoots up. This is a typical way to grow in size for grasses. 

All bamboo species, including the big ones that have a woody composition like Moso and Guadua, use the same method for photosynthesis as all grasses called C4 carbon fixation or simply C4 for short. 

Why bamboo is not a tree

A tree is a perennial plant with an elongated stem(trunk), supporting branches and leaves in most species. 

The  trunk is made of woody tissue for strength, and vascular tissue to carry nutrients and water from one part of the tree to another. 

Most trees are surrounded by a layer of protective layer of bark. 

Bamboo differs from trees in many ways but one of the most obvious is the way they grow in size. 

A single culm of bamboo emerges from the ground at its full diameter and reaches the maximum height in just one growing season. It then stays the same size for several years. It grows new branches with leaves in the next seasons but the plant will never grow wider or higher after it ends its rapid growth period. 

Tree trunks, on the contrary, grow wider and taller for decades and sometimes even centuries.

In bamboo, as in other grasses, the culms are hollow between the nodes. Trees have a completely different way of growing and are full of dense woody tissue. 

Another huge difference is that bamboos do not have bark like trees have. Bamboo has protective leaves surrounding the culm in their prime stages of growth but later there is no special protective barrier for the culms. 

How grasses are used

The Poaceae or grasses are the most economically important plant family in the world. 

They provide staple foods from crops such as maize, wheat, rice, barley, and millet and others. Through direct consumption, grasses provide about 51% of all dietary energy to humans. 

Grasses are also crucial in feeding and growing meat-producing animals. 

Bamboo and other grasses like thatch and straw are widely used in construction.  

An unbelievable amount of products in all sorts of industries use bamboo and other grasses. Bamboo alone is used in thousands of ways all over the world. 

Featured image by Blondinrikard Fröberg, Flickr, CC BY 2.0
Tea Kit image: Alan Levine, Flickr, CC BY 2.0