Natives to North America, locust trees are a hardy and fast-growing flowering plant belong to the Fabaceae family. And you can easily identify a locust tree with beautiful, lace-like pinnate (or compound) leaves that fall like grapes from long branches, then drooping plumes (racemes) of white, often sweetly scented white flowers, that look a bit like sweet peas.
These wonderful plants, both trees and bushes, grace gardens and parks all over the world, and you can have their fresh elegance in your garden if you want.
Technically, locust trees are two genera of plants, Robinia and Gleditsia, but commonly also the carob tree and African been tree are called “locust”. However, even though there are more than 22 species of locust trees, the two most popular types of locust trees are Gleditsia triacanthos (honey locust) and Robinia pseudoacacia (black locust). But they are few more few varieties that perform particularly well in home landscapes.
So, whether you are looking for the perfect tree for your landscape or want to learn to identify the different types of locust tree, this article can help.
Keep reading to learn more about the different locust tree varieties to find one that fits your particular landscape needs.
Locus Trees in Your Garden
You will find locust trees in public parks and large gardens, because their presence adds a very fine and elegant texture to the foliage when you look at them from afar.
Then, as you get near, according to the season, you will see the many beautiful “drooping spikes” (racemes) of flowers, a bit like those of wisteria, but usually white, or the sometimes very decorative pods later in the season.
The decorative value of locust tress is therefore a combination of the general shape, the branches, the shapes of the leaves, scent and look of the flowers and the shape and color of the pods too. The wood too can be very interesting, of varying colors, and with a smooth and tough looking texture.
As we said, locust trees are two genera of plants, Robinia and Gleditsia, but in this article, we will also look at two similar trees that botanists don’t call locusts but many gardeners do: the stunning carob tree (Ceratonia siliqua) and the wonderful African locust bean (Parkia biglobosa).
9 Types Of Locust Trees
There aren’t many varieties of locust trees in the world, in fact, only a few can be grown in gardens for their beauty. But those that you can grow are really wonderful plants.
Here are some different types of locust trees that perform well in home gardens:
1. Honey locust tree
2. Black locust tree
3. Carob tree (or old world locust tree)
4. Water locust tree
5. Frisia black locust tree
6. Twisty baby
7. Bristly locust tree
8. New Mexico locust
9. African locust bean
These are jewels of Nature, all original and suitable for different gardens and needs, just look at them and I trust you’ll find the one you are looking for.
1. Honey Locust Tree (Gleditsia triacanthos)
One of the most popular types of locust trees with gardeners all over the world, honey locust is a particularly elegant variety thanks to its arching leaves radiating in clumps from a central point, a bit like rosettes.
The leaves will start off light green in spring and then turn darker, but in the fall, they will turn an amazingly rich and bright yellow, which will boost the energy of your garden. The canopy is thick enough to block sunlight, which makes it ideal to create a nice shady a restful corner in your garden.
The branches are thin and very elegant too, and the grey trunk is covered in massive thorns of a purple color; while they make climbing the tree impossible, they add a quirky but beautiful feature to this variety of locust trees.
The inflorescences if honey locust are not as thick and rich as other varieties, but they are still beautiful and nicely scented. The pods, that bend and curl partially, start off green, then they turn red and finally brown.
As a stand alone tree, this is a good choice for any garden, as it can hold the attention of visitors from spring to late fall. You can, however, also grow it with other trees, in large compositions.
2. Black Locust Tree (Robinia pseudoacacia)
No visitor to your garden, Human or pollinator, will resist the amazing, all encompassing sweet perfume of the flowers of a black locust tree.
This may explain why the black locust is possibly the most popular locust tree variety in parks and gardens around the world. It has a very decorative shape in both its trunk and branches and its foliage, in fact.
The trunk, in fact, which can become fairly large, grows straight and then branches off with balance and elegance to create what look like large fronds of foliage that arch and droop, especially when the rich, generous and scented flowers fill them with white.
The leaves are of a bright green color and when this shade mixes with the white of the racemes (the inflorescences), the shape of the reddish black branches is set off very nicely.
The pods are smaller than many other locust trees, but they achieve a particular decorative quality thanks to the huge number a single specimen will produce, especially as they turn bright red and then brown.
It may or may not have spines, bit it will tend to grow them on young suckers.
The crown of this locust tree is oblong on to of the straight trunk, which gives it an overall look that you would be excused to call “Japanese” or “oriental”, though this tree is native of the United States.
Its presence in any garden will not go amiss; an elegant stand alone tree that you can also use for small woods or wooded areas, or, if you want, as a focal point at the end of a large lawn, this is a fairly easy tree to grow, strong, very adaptable and with good resistance to pest and disease.
3. Carob Tree (Ceratonia siliqua)
Think Mediterranean trees and orange and olive will come to mind, but if you actually talk to local people, the “Old World Locust Tree”, a.k.a. the carob tree should actually complete this “trinity of Mediterranean trees”…
Yes, because these majestic plants are as part of the landscape of Sicily and other Mediterranean regions as citrus trees and drooping olive branches, and also part of their traditional economy.
Having a carob tree in your garden is like having a motherly (or maybe fatherly) and benign presence; the tree has a “protective” look, with its huge trunk, wide spread and shading canopy.
The trunk of the carob tree is a work of art by Mother Nature; with large, smooth, muscular ribs of hard, dark wood, they can grow to be 5 feet wide (1.5 meters). This tree will tend to grow in spread rather than height, giving it its distinctive protective look, like a wise old man guarding your garden.
The branches open wide and with great dignity to hold a canopy that will provide shade and privacy from peering eyes.
The leaves are dark green, large and fleshy, with a beautiful texture, and it too will grow racemes of beautiful and sweet smelling white flowers, and lots of them.
Then, the pods will come, twisting, long and succulent, and, what is more… edible! Yes, because the fruit of this tree is very sweet, like honey, and they can be eaten instead of chocolate or turned into syrup to replace sugar… Much healthier than white sugar and rich in Vitamin B12, this should be a staple in the diet of all vegans, also in its flour form.
As a funny cultural note, the seeds are extremely hard, and they are called “karats” as they were used as the basic measure to weigh jewels…
I would definitely use a carob tree as a protagonist in a lawn or even desert garden, or as a centerpiece in a Mediterranean garden, in fact, few trees bring back the very essence of that region as those majestic “Old World Locust Trees” that alone rise from hills of scorched land and dry grass…
4. Water Locust (Gleditsia aquatica)
Water locust may not be the impressive tree you want as a centerpiece in your garden, but it is an excellent choice for small woods and shaded areas, especially of you want to give shelter to a river or water source.
In fact, this tree looks great in small (or even larger) groups and it likes wet places, where it can become naturalized and loom after itself. Original of South Eastern States in the USA, especially of the Mississippi Basin, this plant has found a good habitat around irrigation ditches and canals in many parts of the world.
It is also fairly common in large parks, where it can provide an easy to grow backdrop to large lawns and other open spaces.
The grey trunk and branches do not have the same striking elegance of the black locust tree or the honey locust, as they grow with a wilder, less “manicured” look. The fronds, however, provide a lot of shade and secluded spaces, and they can even be used as barriers for outer borders of large plots of land.
The leaves have a multipinnate shape, which means that the oval leaflets grow on lateral stems radiating from a central one. This makes them less attractive from an architectural point of view, and with a wilder, more “bush like” look, which will suit a more “natural looking” part of your garden.
It too will grow many beautiful racemes with scented flowers that will attract lots of pollinators. The pods, then, will be small and short, starting with a pale green color and then developing into reddish brown.
The spines will provide extra protection from intruders if you wish to use it to edge and shelter your property, as the tick canopy will keep unwelcome eyes beyond your garden’s perimeter.
5. Frisia Black Locust (Robinia pseudoacacia ‘Frisia’)
A black locust tree cultivar, ‘Frisia’ stands out for the intricate, filigree like texture of its canopy, which is of a bright chartreuse green color (almost yellow) and it looks stunning and highly decorative in the Sun.
The crown of the tree is oval and upright, but with an irregular silhouette. A beautifully shaped tree, very balanced, with a straight brown trunk and elegant branches, this variety will certainly suit both a modern garden and a more traditional one and, in many ways, given its delicate look, it will also look great if you are looking for the romantic feel.
This romantic look will be greatly enhanced when the blooms come, as they are not white, like with most locust trees, but pink!
6. Twisty Baby (Robinia pseudoacacia ‘Lace Lady’)
If you don’t have lots of space in your garden and you still want to grow a stunning locust tree, or if you want to grow a shrub with the “leaf embroidery” that locust tree foliage has, then twisty baby, another black locust variety is perfect for you!
This smaller specimen with zig-zagging branches and will form large shrubs with beautiful, thick and rick drooping pinnate leaves of a rich green color that look like they are hanging from the branches. The leaflets then tend to twist onto themselves, which makes them look like curls…
The ensemble is visually stunning indeed, and in fact it can lift any garden with its presence; the trunk and branches often form interesting and artistic shapes; they have that “bonsai” look that is so difficult to get…
The flowers come in small racemes of nicely perfumed white flowers, but this variety is not a very generous bloomer.
You can, if you wish, train this plant into a small tree and as such it would look great in a small but orderly urban front garden, for example.
A little beauty of the locust tree “family” that has a very bright future in gardening…
7. Bristly Locust Tree (Robinia hispida)
Also known as moss locust, or rose acacia, this locust variety is a shrub that has very lush, deep to dark green leaves with round leaflets and pink to purple flowers that come is clusters of fairly small, but eye catching racemes.
This locust shrub takes its name from the fact that when the pods come in late summer, they are covered by a bright red “beard” that makes them stand out in any garden and add that exotic and unusual touch to your green spaces.
The branches, which are brown and mainly thin also give this plant the “hirsute” in its Latin name, as they are covered in bristle hair, which makes this plant uniquely attractive and beautifully weird.
However, this plant propagates very fast and it can become invasive, in fact, you cannot grow it in Midwest States (except Missouri) as it is classed as a “noxious weed” there.
This small locust tree plant is a suitable for both as a member of a large border or hedge, or on its own, in which case, I would find it excellent for a place in full sight in a tidy urban or suburban garden, by a loan or next to a patio.
8. New Mexico Locust (Robinia neomexicana)
Yet another shrub shaped locust tree m this time with a deceiving name, as this beautiful plant does not come from New Mexico, but from Colorado and Utah… Still, this does not detract from its beauty and decorative value…
It is an excellent choice of plant if you want to add some beautiful foliage to your hedges and large borders, or if you fancy a little and quote elegant shrub to soften the lines of your garden. The overall shape of the canopy is spherical, and the branches and foliage look light and airy…
The racemes are not very long, but they dot the foliage with bright and eye catching pink spots that also add a pointillist effect to the appearance of this plant.
Perfect for a delicate garden or a spot where you want your visitors to appreciate your refined taste in plants and landscaping.
Do not eat the bark, root and seed of this plant as they are said to be poisonous.
9. African Locust Bean (Parkia biglobosa)
Of all the plants called “locust”, this one is the most original, but also one of the most beautiful and one that can really transform a forlorn plot of land into a botanical wonder and an unforgettable garden.
Calling this tree elegant is an understatement, in fact! This amazing plant has all the grace of the orient and the still beauty of African trees, where, in fact it comes from. You could well picture it standing proud and majestic in a semi-desert while at the same it gracing the skyline with its perfectly balanced silhouette.
But as the Sun gets behind it, and as you get close, a bit like Chinese shadows, this tree starts revealing the dancing dynamics of its artistic branches and then the decorative lace pattern of its foliage, which remind me, oddly enough, of the impressive artistry of thin lines and dappled light you get in stained glass windows in Gothic cathedrals…
But then you go under the canopy of this dreamlike tree and you discover that it does not have racemes of flowers, but round and furry red balls instead. They look a bit like Christmas balls hanging from the branches of a very improbable Christmas tree…
Eye catching thanks to their color and unusual shape, they can bring that touch of velvety luxury to your garden, while keeping your visitors gazing.
The pods, however, look much more like those you find hanging from other locust trees, and they come in clusters of long and brown “husks” with a yellow and edible pulp inside.
You will need a large space for this tree, but if you do have the chance to grow it, please make it the protagonist of your garden, finding it the most visible spot ever, in the middle of a lawn, for example…
Nor will it give you a full shaded place, as the light will keep coming through its very thinly spread leaflets that look like the lace on the cuffs of an Elizabethan actor or nobleman.
This is a plant that will wow anybody who looks on it, from a distance, close by, and at any time of the year.
Locus Trees, for Gardens but Not Just!
Locust trees are wonderful plants for many reasons; their foliage, their shape, their beautiful, bountiful and sweet smelling flowers, then the pods come and they add an extra touch to their intricate beauty… The list goes on…
Some are massive trees, like the African locust bean, while others are bushes you can grow in small back gardens, like the bristly locust tree, and you can find one that fits and suits many types of gardens and hopefully your taste too…
But there is more… these trees have contributed to the economy of whole regions, providing food (with their beans and even flowers), even very rare vitamins, some have medicinal qualities, but they have also given shade in hot places and very precious wood.
Growing a locust tree is more than just growing a plant, it’s like bringing the whole culture of a place to your garden, sometimes a culture that is thousands of years old!
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Amber Noyes was born and raised in a suburban California town, San Mateo. She holds a master’s degree in horticulture from the University of California as well as a BS in Biology from the University of San Francisco. With experience working on an organic farm, water conservation research, farmers’ markets, and plant nursery, she understands what makes plants thrive and how we can better understand the connection between microclimate and plant health. When she’s not on the land, Amber loves informing people of new ideas/things related to gardening, especially organic gardening, houseplants, and growing plants in a small space.