Locust trees are a common sight across much of the United States in both rural and urban areas. There are multiple species from the same family of trees, Fabaceac, the most popular are the black and the honey locust. They both thrive in warm climates.
The varieties share many similarities. However, it is their differences that are most notable.
Both types are rapid growers in their native parts of their respective country. The black locust has multiple practical uses as timber; the honey locust is regularly cultivated as landscaping in towns and cities.
Although both trees prefer a warm climate, the black locust is hardier than the honey locust and grows in inhospitable conditions.
Their leaves, bark, seeds, and flowers are just some of the factors that make it easy for the untrained eye to tell them apart.
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Where the Black Locust and Honey Locusts are Native
The honey locust, Gleditsia Triacanthas, is common in the central-eastern regions of the US. They are native as far north as Pennsylvania and as far west as Nebraska.
In the wild, they are found mostly in the moist soil of river valleys where they can grow beyond 100 feet tall.
The black locust, Robinia Pseudoacacia, is native to the southeast US. They also thrive in North America, Asia, and Europe.
They prefer well-drained soil but are hardy and adaptable, allowing them to grow in regions with poor soil quality, high salt levels, and air pollution.
More commonly known as the thorny locust, the honey tree has a covering of long thorns that grow to around 4-inches long. They are most often found around the base of leaves and along branches and tend to get sharper as the tree matures. Initially, they are green but turn brown and brittle over time.
In comparison, the dark brown bark of the black locust has multiple grooves around its diameter. It creates the impression that it has had tight elastic wrapped around it for long periods.
Although the black locust's bark feels hairy, it too might have some sharp thorns. There are fewer than on the honey tree; they congregate at the tree's base. They are shorter but every bit as sharp.
In the wild, the honey locust grows over 100ft tall. It remains at a more conservative 40 – 70ft when cultivated for landscaping. Black locusts grow between 60 – 80ft tall and have a magnificent canopy, often reaching 30ft wide.
The leaves of the honey locust are small and bright green. When they're preparing to drop in the winter, they fade to dull yellow. The new growth is ready to come through in early spring. Although both the honey and black locusts are deciduous, the black tree spends many more bare weeks between the leaves dropping and regrowth.
They are feather-shaped and bipinnately compound as young trees, becoming pinnately compound as they mature.
The black locust leaves are noticeably bigger. They are oval and are green but with a bluish tinge. Each one is a simple compound; they grow from every non-uniform branch. It creates both shade and light beneath the tree, ideal growing conditions for many plants.
The Flowers of the Locust Tree
The black locust is stunning when in flower. The tree becomes crowded with tiny white flowers that hang in clusters. Each group measures between 4 and 10" long.
Although the heavily-scented flowers are predominately white, some cultivators successfully achieve pink, lavender, and purple flowers.
The tiny flowers also form in clusters on a honey locust; however, they're denser on male trees. On female trees, they collect more loosely. Both sexes have white flowers with a soft green hue, and they have a strong, heady aroma.
Locust Trees and Their Seed Pods
The seed pods of the honey locust are distinct due to their size and shape. They can grow as large as 18" but are averagely 12" long. They are flat strips that often curl into spirals as the seasons' progress.
They start their life as a lime green color; as fall approaches, they turn reddish-brown.
They are an excellent food source for countless animals, including squirrels, deer, rabbits, and birds.
Each pod contains 12-14 seeds that are dispersed by grazing herbivores. Cattle and horses digest the pulp before depositing it elsewhere, where some seeds germinate.
The seed pods of the black locust are much smaller; they measure just 4".
If you're familiar with the buds of the mimosa tree, you will undoubtedly notice the similarity.
The dark brown pods contain around 14-seeds, but beware, they are toxic.
Uses for Locust Trees
Despite its name, the honey locust does not attract bees to collect pollen to make honey. Instead, it refers to the sticky-sweet pulp inside the seed pods.
Honey locusts are rapid growers and have stunning non-uniform branches that create lots of light and shade. They are a street planner's dream, especially as their leaves are so small that they don't create an issue when they drop.
Unclogging municipal drains and leaf clearing is an expensive affair. The tiny leaves of the honey locust are a good money-saving method while creating a softened inner-city landscape.
The seed pods contain a sweet sap that was used by Native Americans as medicine. It is still used in the production of tea and beer.
It is also an ideal sweet feed for livestock; it has a calming effect on cows and goats that find the milking experience uncomfortable.
The wood of the honey locust is high-quality, strong, and durable. Despite this, landscaping is its main purpose. Certain niche furniture companies handcraft small amounts of honey locust furniture.
Uses for Black Locust
Surprisingly, it is the black locust that is predominant in the honey-making chain.
The aromatic clusters of flowers in their multitudes are a magnet for the honey bee. With so much pollen available, they are a great nectar source.
Their wood is hard and high-quality, making it ideal for the construction of sheds and fencing. It is robust and, as it grows quickly, remains a constant source of durable timber.
The timber is dense and, despite being hard to cut, makes perfect firewood. It burns slowly and lasts a long time before extinguishing.
The black locust thrives in hardy conditions, creating stunning cascades of aromatic flowers as it grows. It produces high-standard timber that is essential to fencing manufacturers and other industries.
The honey locust creates impressive landscapes in otherwise gray, built-up areas. It grows fast but may stifle other plants and be susceptible to disease and pests.