What Is a Shrub? Shrubs vs. Bushes, Trees, and More (2024)

Trees, shrubs, and bushes are all similar in their woody stems and green leaves, and each can resemble the other based on how they're pruned or allowed to grow. But there are key differences to tell them apart, and the words don't necessarily refer to the same characteristics.

The terms 'shrub' and 'bush' are often used interchangeably, but they actually refer to different things. Bush actually refers to the growth habit of various plants, while a shrub refers to a specific type of plant. That means some shrubs may be bushes because of how they grow, while bush is a more general term.

Here, you'll learn more about shrubs, what defines a shrub, and how shrubs compare to trees and bushes.

What is a Shrub?

Shrubs are defined as woody plants with several perennial stems that may be erect or may lie close to the ground, though some can be grown taller as shade shrubs. Shrubs will usually have a height less than 10 feet and stems no more than about three inches in diameter.

According to renowned British garden designerDavid Domoney, a shrub is defined as a woody plant that is smaller than a tree and generally has a rounded shape. Meanwhile, Merriam-Webster calls a shrub "a low, usually several-stemmed woody plant," and "a woody plant that has several stems and is smaller than most trees."

Shrubs vs. Bushes

While shrub and bush are often used interchangeably, a bush describes the way a shrub or other plant grows. A shrub is a woody plant with several stems, and it is a bush when it grows densely and closer to the ground. Think of a shrub as a the scientific classification of a plant, while a bush is a general description of the way it grows.

Shrubs vs. Trees

Trees and shrubs are both woody plants, as distinct from the herbaceous, fleshy-stemmed plants that comprise the other half of the plant world. We all think of a shrub as being smaller than a tree, but there are more differences than size alone.

It's worth noting that there is a scientific classification distinction between trees and shrubs, so really, the debate over if something is a tree or shrub is mostly a linguistic and aesthetic issue that matters the most when you're deciding what to plant where, which trees and bushes for landscaping to choose, and how big something should be.

Also, trees are sometimes grown as shrubs; hemlock, hornbeam, and hawthorn trees are often grown as shrubs in urban environments.

How to Identify Shrubs, Bushes, and Trees

Once you know that a plant has woody growth, you can determine whether itis a tree, a shrub, or a bush. Here are four ways to make that determination.

Growth Habit

Jerry Goodspeed, USU Extension horticulturist, explains that growth habit and size are one of the key differences between shrubs, bushes, and trees. "Trees add shade and perspective, and usually frame our homes and yards. Shrubs are the plants we relate to—they help us feel a part of the landscape because they bring it down to our level....A shrub or bush is a woody plant with a mature height of between one and a half and 10 feet. Anything smaller is ground cover. Anything larger is a tree. Most bushes are also easy to place in the landscape."

Note that there is some disagreement about the maximum height of shrubs. Goodspeed defines the maximum height of a shrub as 10 feet, while others, as noted above, define the boundary as 13 feet. In any case, both heights are generally less than that of mature trees.

A shrub is a bush when it grows in a low, dense shape.

Shape

The generally acknowledged definition of a tree is a woody plant having one erect perennial stem (trunk) at least 3 inches in diameter at a point 4 1/2 feet above the ground, a definitely formed crown of foliage, and a mature height of at least 13 feet.

Meanwhile, a shrub has several main stems growing from ground level, rather than one trunk

Bark

Shrubs, trees, and bushes will all have a hard, woody bark, though the bark of smaller shrubs and bushes will often match its scale.

Leaves

The leaves of a shrub or bush are typically smaller and denser. You'll have many branches closely packed within a smaller shape and height. Meanwhile, a tree will often have an airier feel to its branches and leaves.

What Is an Herbal Shrub?

An herbal shrub is an herb that has a shrub-like growth pattern. This could be something like rosemary or lavender that eventually grows a woody stem and can reach several feet in height. These are both examples of herbal shrubs that are grown as evergreen shrubs in some climates.

Many people think, for example,that so-calledbanana treesare trees, but in fact, they are considered the world's largest herb.

Notable Exceptions

These definitions serve as good starting points for distinguishing between trees and shrubs, but, as withmost things, there are exceptions. As long as you follow the general definitions, though, you should be able to decide whether a plant is a tree or a shrub.

Some trees, such as river birch and Japanese maple may have multiple trunks. And some shrubs can be shaped into small trees by training one main shoot as the trunk.

Nutty plants such as hazelnuts (filberts) are plants that can be grown as either a shrub or a tree. If left alone, it can become a “trub.” A trub is a plant that cannot decide if it is a tree or a shrub. It gets bushy, but it grows to a height of more than 15 feet, which classifies it as a true trub.

Jerry Goodspeed, Utah State University Extension horticulturist, says, "Hazelnuts...should be trained and grown as a tree because they are more productive as a tree and make a mean-spirited, lousy shrub...When trained as a tree, hazelnuts can grow to about 20 feet high, with an equal spread.