Is a Cactus a Tree?
Easy explanation for non-botanist

Introduction

The phenomenal Cacti have over 1700 species all over the world. Many of them even produce flowers and fruits. But can we categorize them into plant types, or could we even call them trees?

A cactus cannot be called a tree, as it has a wooden stem. Moreover, trees do not have succulent stems, which cacti have. However, some cacti species can attain a very tall height, looking like trees.

Cacti can be found primarily in the desert and hotter climates. But you will find some species in tropical or sub-tropical regions too.

What are the different plant types?

A plant may belong to any of the following types:

• Shrub: A shrub is usually of moderate-sized plant that lasts throughout many seasons.
• Bush: Bring together many shrubs, and you get a bush!
• Vine: A type of long climbing plant that looks like a rope.
• Young tree: Any plant that is less than 32 feet in height, with the structure and wooden features (elements) of a tree.
• Grass: These have joint stems, and some of the grass plants may have flowers or other produce growing on top of them.
• Herb: A herb is the plant type that produces edible seeds, flowers, or leaves. These could be used in cooking or even medicines.

The different plant types may sound confusing at first, but they’re not. Especially if one considers a cactus, it strikes out as a plant type of its own.

What is a cactus?

A cactus is a plant distinguished by its spines or thorns!

A cactus belongs to the Cactaceae plant family. It has 127 genera and around 1700 species growing in various desert and sub-tropical regions.

What are the different types of cacti?

Not all cacti look the same, do they?

Depending on the shape of cacti, they can be any of the following:

• Round: This cactus is very well-rounded and the thickest of them all.
• Columnar: These are tall and thin cacti that look like columns.
• Short stem: These are very tiny cacti species.

What are the most common cacti species and do they have tree characteristics?

Some of the most common cacti species are the prickly pear, the moon cactus, and the saguaro. One of the oldest species is the Pereskia, which has some apparent tree characteristics.

A Pereskia plant typically consists of a crown similar to a tree. This is one of those few cactus that has leaves and so, it may look tree-like. It is also more tolerant to regular potting soil. 

However, the overall characteristics are that of succulent plants and most of the cacti. Even this species has areoles and spines, which trees typically don’t have. Hence, even the Pereskia species cannot be classified as trees. This species cannot grow in deserts.

Did any of the older or extinct cacti species ever have wooden trunks and leaves?

Some cacti species in the desert produce barks. This is usually in the bottom, the base of the cacti.

However, these are in no way of the same structure as the barks of a typical tree. The wooden tissues of these desert cacti are very sensitive, compared to trees that usually have very tough and sturdy wood.

What is the definition of a tree?

There are some requirements for a plant to be classified as a tree!

A tree needs to have wooden branches and stems and a height of over 32 feet to be classified in the category of trees.

Keeping the definition in mind, we can clearly not see any wooden branch, stem, or other parts in most cacti species.

What is the basic difference between a cactus and a regular tree?

Other than lacking wooden parts, a cactus also has different needs.

A regular tree will also have different sunlight and water requirements, although there are some succulent varieties in trees.

There are some trees that require a well-draining soil mix just like a cactus does, but this is not a characteristic of all trees. On the other hand, all cacti require a well-drained, aerated soil mix. So this is not common quality of tree types and cacti, and hence a cactus cannot be classified as a tree.

Can any cactus look like a tree?

Cacti that can grow extremely tall may resemble trees.

Any cactus that grows up to 32 feet or taller can look like a tree, while biologically not being one.

The Saguaro cactus, native to the desert region, can indeed look like a tree. This cactus species is one of the tallest to exist, although its population is decreasing gradually day by day.

Can all cactus species be forced to grow to the height of trees?

No, cacti cannot be made to look like trees.

Cacti species can only grow as tall as their particular species usually does.

It is essential to understand that various cacti species have a maximum height they can attain. They can’t grow taller than their natural tendency to grow tall.

Do cacti need to grow tall and tree-like to bloom?

Cacti need sufficient sunlight to bloom.

Cacti don’t need height or a tree-like structure to bloom. Sufficient sunlight conditions are required for a cactus to produce flowers.

A tree may start producing flowers at a certain age. For a cactus, if it has been exposed to appropriate sunlight, it begins to produce flowers. Not all cacti will bloom though. 

What is the shortest cactus species?

The shortest cactus is 1 cm tall, known as Blossfeldia Liliputiana.

This cactus isn’t a tree not just because of its height, but again, because it doesn’t have wooden stems, branches, or even leaves.

What is the tallest cactus species?

Length doesn’t necessarily mean a tree!

The Pachycereus pringlei is the tallest cactus species, with heights that can even cross 19 meters.

Don’t get confused by its tall height though. Just like other cactus species, the Pachycereus Pringlei also doesn’t have branches, barks, or other tree characteristics.

What is an epiphyte?

In simple words, an epiphyte is any plant that grows from another support. This includes trees as well. Since there are no other plants growing out from a cactus, it’s straightforward that cacti certainly do not belong to the tree plant type.

Cactus vs. Tree: A side-by-side comparison

	Cactus	Tree
Branches and barks	Yes (some species have barks but not like tree wood)	Yes
Leaves	Mostly spines except some species like the Pereskia that have leaves	Yes
Epiphytes (other plants growing as support)	No	Yes

So is a cactus a tree?

A cactus doesn’t have the functions of a tree, although some species like the Pereskia may look tree-like because they have leaves. The common features of a tree are wooden branches and stems, leaves and it can also support the growth of other plants. Where some trees require a well-draining soil mix to thrive, not all trees need aeration. However, almost all cacti need proper drainage, so clearly a cactus is not a tree!

If you want to learn more about a cactus in the simplest way, read this amazing post on whether a cactus is a leaf or not.

Posted in: Cactaceae Cactus Spine Succulent Facts