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Black Locust Leaves: Everything You Need To Know

Black Locust tree produces beautiful feather-like leaves, accompanied by white blossoms that make your garden not less than heaven.

The Black Locust leaves contain several pinnate-arranged leaflets measuring 1-2 inches in length, which gives them a feather-like appearance, and they often boast green or bluish-green shade, which is very different from honey Locusts’ light green leaves.

The guide does not end here; continue reading to learn more about Black Locust leaves.

How Do You Identify Black Locust Leaves?

Did you know the Black Locust tree (Robinia pseudoacacia) has been grown for centuries to be used as timber, firewood, erosion control, and to attract honey production?

This durable tree is known for its many applications, including ornamental leaves, which add to its overall charm.

You can identify Black Locust trees by their compound leaf structure, composed of multiple leaflets arranged along a central rachis, which is visually distinct from other tree species.

Black Locust with flowers and leaves
The leaflets display a pinnate arrangement, giving them a feather-like appearance, similar to the popular ZZ Plant.

Here are some critical facts about Black Locust leaves.

NameRobinia pseudoacacia
Common nameBlack locust
Leaf structure Compound (Composed of multiple leaflets)
Leaf arrangement Pinnae pattern along the rachis
Leaf shapeOvate to elliptical in shape with a rounded or slightly pointed tip and a wider base
Leaf size1 to 2 inches (2.5 to 5 cm)
leaf edgesThe edges are smooth and lack any noticeable serrations or teeth
Leaf color-Vibrant green to bluish-green in spring and summer
-Yellowish in late fall and winter
Leaf textureThey have a smooth texture, without any notable hairiness or roughness
Leaf veinsThey are typically not very prominent and are difficult to see

One remarkable feature of black Locust leaves is that they attract ants, which protects the tree from any insect larvae that may feed on it.

Black Locust Vs. Honey Locust Leaves

Many gardeners confuse honey Locust leaves for Black Locust because of their similar appearance.

First, the Honey Locust (Gleditsia triacanthos) is an entirely different tree that only shares the term “Locust.”

Both black and honey Locusts share similar compound leaves with multiple leaflets and ovate to elliptical leaves. Similarly, they both have thorny varieties, adding to the potential confusion.
Black Locust vs Honey Locust
Black Locust leaves are blue-green in color, while Honey Locust has bright green leaves.

However, you can differentiate if you look closely. Here are a few stark differences.

Black LocustHoney Locust
The leaves are green to bluish greenThe leaves are bright green
The leaves are 1-2 inches longThe leaves are 3/4 to 1.5 inches long
It commonly has thorns along its trunk and branches along the leavesIt has distinctive long thorns on its branches along the leaves
Black Locust is native to the regions of southeastern United StatesHoney Locust is mainly native to eastern and central North America
The leaves fold closed in wet weather or night, and the leaves are much broaderThe leaves do not possess a leaflet at the leaf stem tip

Talking about the blooms, the black Locust produces white fragrant flowers and seed pods that deter predators, while honey Locust flowers are more greenish-yellow and attract animals.

Are Black Locust Leaves Edible?

Black Locust leaves are not edible as the foliage contains toxalbumins (toxic protein molecules) and alkaloids called robinin.

These toxic compounds inhibit protein synthesis and can cause cell death, often leading to severe poisoning, nausea, weakness, flushing, and vomiting.

The toxalbumins enter your body after ingestion or inhalation of leaves or even through skin absorption, where they have specific binding sites on cell membranes, allowing them to attach to cells and disrupt cell membranes’ activity.

Most gastrointestinal issues develop within 6 hours after ingestion of leaves, which can also lead to further complications.

Therefore, they are better kept away from small animals, pets, and children.

Predators like deer and rabbits often avoid consuming Black Locust leaves, making these trees the perfect pest-deterrent plants around your garden.

Although there are reports of some cultures using tree flowers for consumption, no usable recipe for black Locust leaves seems to exist.

In comparison, the black Locust flowers appear to be nontoxic or less toxic, but you should exercise caution when handling them.

Why Does Black Locust Leaves Turn Yellow?

Like any deciduous tree, Black Locust leaves will naturally turn yellow in the fall before losing their leaves.

Therefore, it is not a reason for concern as long as your tree is healthy.

However, the Locust leaves will begin to yellow before fall, which may indicate a severe problem of environmental factors and underlying issues.

Here are some common reasons Black Locust leaves and their fixes may turn yellow.

1. Environmental Stress

Anything from drought, excessive heat (Above 85F), or inadequate nutrient availability may redirect resources away from the leaves, leading to yellowing or leaf drop.

You could tell it by yellowing tips, patches of browning, and leaf burns.

As a solution, water more frequently to prevent transpiration, especially during drought.

Mulching around the tree’s base will help retain moisture and regulate soil temperature.

2. Pest or Disease Infestation

Although rare, pests or diseases will turn leaves yellow, including spotting or discoloration.

Some typical pests include aphids and diseases like powdery mildew or leaf spot leading to yellowing.

Applying Neem or horticultural oil on the affected parts can eliminate problems.

Other mitigation solutions include targeted insecticides or fungicides and pruning affected branches.

3. Nutrient Deficiency

Black Locusts are heavy feeders, particularly of nitrogen. The lack of proper nutrition can cause yellowing of leaves.

It is characterized by yellowing starting from the tips and spreading towards the base.

First, conduct a soil test to determine any specific nutrient deficiencies.

Apply a balanced fertilizer formulated explicitly for trees per the manufacturer’s guidelines.

4. Waterlogged or Poorly Drained Soil

Black Locusts can suffer from waterlogged or poorly drained, often leading to root stress or root rot.

It can affect the tree’s ability to uptake water and supply nutrients to the leaves.

As a solution, cut back on watering or aerate the soil to improve drainage, and begin watering once the problem subsides.

5. Herbicide Damage

Applying herbicides or weed killers can prove to be deadly.

They can seep into the roots through drift or direct contact, causing yellowing.

As a solution, minimize further exposure to herbicide and water generously until the chemical seeps away from the roots.

From Editorial Team


Pay special attention to changing the color of black Locust leaves, as they are the first to indicate any underlying problem.

Water every 3-5 days, use moist loamy soil, and apply mulching to retain soil moisture. They do best in temperatures between 75-85°F (25-30°C) and medium sunlight.

Additionally, use balanced fertilizer to ensure a healthy plant. Otherwise, apply a fertilizer slightly higher in phosphorus to witness large, beautiful flowering.