Walking around your neighborhood you may notice a variety of plant life. There may be some small plants that remain close to the ground and others that are tall or wide and bushy. What makes one plant considered a tree, while another plant is considered a shrub? What is the difference between a shrub and a tree?
Woody plants are plants that grow hard, wooden stems stiff enough to support their structures above ground. Typically, woody plants are perennials, meaning they live for longer than a year or two, some for decades or longer. Generally, the stems are considered durable, and woody plants tend to be larger than other perennials, such as grass.
There are three main categories of woody plants: trees, shrubs, and vines. Both shrubs and trees can support their structure above ground. Vines grow woody stems, but the stems are not stiff enough to support their weight, so they grow on structures that can support them, such as fences or buildings, or even on other plants.
Defining Features of a Tree
Trees are considered a woody, perennial plant. They tend to have one long, slender main stem and few branches on their lower parts. The stem of a tree is what most people call the trunk, and it’s actually made up of mostly dead tissue. Only the outer layers of a tree trunk are still living and growing.
Each year, the tree grows two new rings on the outer woody layer of the tree trunk. In the spring, a wider, thinner-walled layer grows, and in the summer, a thicker-walled second ring grows. The cambium is the live outer layer that continues to grow rings and tree bark.
Trees have a system to move nutrients and water from the roots to the crown, where all the leaves are, and also a system to move the sugars produced during photosynthesis at the leafy crown down to the roots. There is a layer of tissue just outside the cambium called the phloem. It is the phloem that allows movement of the sugars produced during photosynthesis at the top layer down to the roots. As the phloem ages, it dies and becomes tree bark.
The system that allows movement of water from the roots to the crown is the xylem, a thin layer just inside the cambium. When xylem tissue dies, it becomes part of the inner wood layers.
Defining Features of a Shrub
Shrubs are also considered woody plants. However, they have multiple stems and remain smaller than trees. That is, trees are usually taller than 10 feet and have a single woody trunk. Shrubs range from 1 to 10 feet tall and have several woody stems at the base. Anything lower than one foot is not considered a shrub or a tree.
Exceptions to the Rule
As with a lot of definitions, there are some grey areas. It’s not always clear which category some plants fall into. Not all trees will have one tree stem, which can make identification more complicated. Some trees will have multiple woody stems growing from the base. A prime example is the maple tree. Some species are multi-stemmed but are still taller than a shrub and would be considered a tree.
Some trees can be trained to stay short and can be called a shrub. This is often done with fruiting trees to make harvesting the fruit easier since the branches are lower to the ground. There are also many dwarf tree cultivars. These small trees are no more than 10 feet tall and are the result of grafting. They can be ornamental, fruit-bearing, evergreen, or flowering trees.
Though there are some notable exceptions to the rule, if you follow the general guidelines of what defines both a shrub and a tree, you should be able to determine whether the plant is one or the other.
Why Plant a Shrub or a Tree?
Planting shrubs can add privacy and add some color and personality to any garden. If you choose evergreen shrubs to line your yard, you can have yearlong privacy and a beautiful green barrier around your yard. Many shrubs offer beautiful flowers in different shapes and colors during the spring and summer months. Planting shrubs in your garden can add a pop of color and can attract birds and pollinating bees to your garden.
Flowering shrubs can also add some lovely fragrances to your yard. For example, planting lilac or lavender can add both an attractive color and fragrance to your garden. For questions about which shrub would suit your garden the best, contact the experts at Mr. Tree for guidance.
Planting Trees can add shade to your garden, as well as provide shelter to many outdoor critters living in your yard. They also provide shelter for humans, blocking the harsh sunlight or cold wind from our homes and yards. It’s more pleasant to spend time outdoors in a yard or park that has trees.
Planting both trees and shrubs helps the environment by providing oxygen and improving air quality. They also help preserve the topsoil by anchoring it in place with their roots. If you plant fruit trees, you can gain these benefits, plus enjoy apples, figs, lemons, and many other delicious fruits right from your garden.
By following the basic guidelines of what defines a tree and a shrub, you can tell which plants are under which category. If you have any questions regarding plants in your yard, or if you are looking for assistance with planting a shrub or trees in your garden, contact your arborist experts at Mr. Tree. We can help you with all of your tree and shrub planting and care needs.