Locust trees are a type of tree native to the Western Hemisphere that thrives in dry climates. There are two types of locust trees: the desert woody locust (Robinia pseudoacacia) (Black Locust) and the swamp locust (Gleditsia triacanthos) (Honey Locust). These species can be distinguished based on their leaf structure. Desert woody locust leaves have three leaflets arranged in an inverted triangle while swamp locust leaves have five leaflets arranged in a loose fan shape. In addition to these differences, desert woody locusts have smooth bark while swamp locusts have rough bark. Other distinguishing characteristics of both locust species include the color of their flowers, fruit, and seeds. Desert locusts produce white flowers and green berries. Swamp locusts produce yellow flowers and orange berries. Finally, desert woody locuses have four-seeded fruits while swamp locusts produce two-seeded fruits.
The genus Robinia is named after the French botanist Jean de l’Écluse who first described them in 1753. Robinia includes several different species including the desert woody locus, red locust (Robinia rubiginosa), and purple locust (Robinia pseudocana). Each of these species has unique characteristics and geographic distribution. Despite their close relationship, they have different uses and applications.
Desert woody locusts are commonly known as mesquite trees. Mesquites are widely grown throughout Mexico where they play an important role in ecological balance. In addition, they provide food and shelter for many animals and reptiles. Because of their wide range of habitats, desert woody locsters are able to survive extreme conditions such as high temperatures, low precipitation rates, and waterlogged soils. Also, due to their adaptability and hardiness, desert woody locster forests are often used for firewood.
Swamp locusters are primarily found in the southeastern United States. Like desert woody locust trees, swamp locsters are tolerant of harsh weather patterns and have developed a thick and hard outer shell to protect against insects and disease. Commonly known as honey locust trees, they are used as a source of honey and beeswax. Swamp locsters are also frequently planted as hedges along roadways, sidewalks, and park boundaries.
Finally, Robinia is a genus of leguminous plants found in North America. As a member of the pea family, Robinia is closely related to the common bean and soybean. Like other members of the pea family however, Robinia is not edible. Rather, its leaves are used to make paper.
Lets look at some of the know Locust Trees:
Black Locust Tree (Robinia pseudoacacia)
The common locust tree is native to North America, and grows best in rich, well-drained soils. Its branches grow straight up to 10 feet tall and produce bright yellow flowers in early spring followed by greenish brown fruit in summer. Fruits mature in fall and ripen to golden orange. Fruit is edible, high in protein content and contains small amounts of fat. Fruits are eaten fresh or dried. Locust trees have low water requirements and tolerate drought conditions well. They thrive in full sun and do not need much fertilizer or pruning.
Common locust trees have been planted along highways, railroad tracks and river banks due to their attractive foliage and colorful fruits. In addition, they provide beauty and shade for yards and parks, and make excellent wind breaks.
Honeylocust (Gleditsia triacanthos)
Honeylocusts are deciduous shrubs that are native to eastern and central North America, where they often grow along roadsides. They grow rapidly in warm regions, reaching heights of 8–10 m and spreading to 1½–2 m per year. They are pollinated by honeybees. Honeylocusts flower mainly in late spring and early summer, producing white blossoms and pink berries. The fruit is edible and nutritious. Pollination is necessary for flowering and fruiting.
Skyline Honey Locust – (Gleditsia triacanthos)
This tree was originally a hybrid between a Honeylocust (Gleditsia triacanthos) and a locust (Robinia pseudoacacia). It has been named Skyline Honeylocust because of its unique foliage pattern. Its leaves have three distinctive lobes resembling honey locust leaves. The flower clusters resemble those of locust flowers, hence the name Robinia locusta.
These trees create a dense canopy over time, which makes them great for blocking out unwanted sunlight. They do not require much maintenance except watering and pruning since they do not get many insect problems. Their fruit is nutritious and contains high amounts of vitamin C.
Bristly Locust – (Robinia hispida)
The bristly locust is a fast-growing deciduous shrub native to North America. Its range extends from eastern Canada to North Carolina and south to northern Mississippi. In addition to its adaptability as an ornamental plant, it also serves as an effective erosion control plant. Because of its rapid growth, it makes an attractive hedge, thicket, or screen. The bristly locust produces abundant flowers that appear in early spring. Each tiny flower contains five or six yellowish petals tipped with red. The fruit is a winged pod containing many seeds.
Imperial Honey Locust – (Gleditsia triacanthos)
The Imperial Honey locust grows in both the United States and Canada. It was first discovered in the US in North Carolina and is native to eastern North America. In some cases, they can grow over 60 feet tall while others may only reach 22. It is considered to be a deciduous tree and requires little maintenance aside from pruning. Its green foliage turns orange in fall and yellow in winter. It blooms in spring and summer. Their flowers produce honeydew honey and their fruit is edible. The wood is strong and durable. It’s fast-growing and easily adaptable.
New Mexico locust tree (Robinia neomexicana)
It is indigenous to the American Southwest. Depending on the type of soil and the amount of sunshine it would receive, it is grown as a shrub or a tree.
It often grows at 10 feet and 7 feet of shade. It can be identified by its substantial, thick branches and profusion of spring through summer blossoms.
Purple Robe locust tree (Robinia pseudoacacia)
It is a well-known shade tree that can endure inferior growing circumstances. It is not suggested for residential lawns, though, due to its invasive nature, thorniness, and somewhat weaker wood than the others.
This tree should be pruned in the summer or fall to keep its pyramidal shape. It could reach a height of up to 20 feet and could withstand soils rich in salt and drought.
Twisty baby black locust (Robinia pseudoacacia ‘Lace Lady’)
It can be grown as a tree or a shrub. It grows at a 20-foot rate and has a little form. It grows to a height of 5 feet when planted in containers. It gets its name from the way its limbs twist and bend, giving it a distinctive appearance.
It gets twistier during the winter pruning. It has dark green foliage that contrasts nicely with the summertime blooms of its numerous, fragrant white flowers.
Sunburst honey locust tree (Gleditsia triacanthos ‘Suncole’)
It grows naturally in cold, wet climates in the Midwest of the United States. It is a shade tree with rapid growth that has an arching habit. It is 30 to 50 feet tall and has a shade of 30 to 35 feet.
Its leaf gaps give grass plants dappled light. In the spring, leaves will start off bright yellow before turning pale green in the fall. Winter pruning and thorough watering are required. It has good accent and shade qualities and is typically disease- and deer-resistant.
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