Robinia pseudoacacia (Black Locust) Fabaceae

The Black Locust is an invasive tree species found (non-natively) is several areas of the U.S. It is known for its beautiful and wonderfully scented flowers. 

Physical characteristics

Leaf: The Black Locust has opposite, pinnately compound leaves containing 7-19 oval leaflets. A pair of thorns grow at the end of each leaf where the nodes would be. 

Flower | Seeds: The flowers are the most distinguishing feature of the Black Locust. They are white racemes that are 8-20 cm long. They are extremely fragrant, with a pleasant sweet floral scent. They bloom late May or early June. The racemes of flowers then turn into flat, brown legumes that contain 4 to 10 seeds each.  

Trunk | Bark: The Black Locust is typically 40 to 50 feet tall. It has deeply furrowed blackish bark. It also has an alternate branching pattern. The root system of the tree is shallow and aggressive. The bark is toxic and can poison animals and humans who ingest it.

Ecological characteristics

The Black Locust is native to certain areas of the southeastern U.S. It is not native to Illinois though it has been planted in several areas. It is able to grow in many types of soil allowing it to be planted in many areas of the U.S. where it is not native. 

 Importance to the ecosystem

The Black Locust is an invasive species taking over many ecosystems to which it is not native. Because of the trees attractive look and smell it is often planted in non-native regions which can lead to it taking over large parts of the area where it was planted. Its root system does enrich the soil benefiting certain locations in need of more nitrogen. 

Relationship with other species

Non-human: The sweet flowers attract a large number of bees and hummingbirds. 

Humans: The Black Locust’s wood is extremely hard and durable making it great for wood work such as flooring, furniture, fence posts, etc. It also makes a good firewood due to its slow burning, little visible flame or smoke, and high heat content; it even burns when wet. 

Pests: The tree has two main pests: the locust leaf miner and the black locust borer. The locust leaf miner attacks the leaves turning them brown by midsummer while the black locust borer larvae carve tunnels in the tree’s trunk. Both can cause serious damage to the tree. 

 

Sources  

http://plants.usda.gov/factsheet/pdf/fs_rops.pdf

http://www.fs.fed.us/database/feis/plants/tree/robpse/all.html

http://www.hort.uconn.edu/plants/r/robpse/robpse1.html

http://www.wildflower.org/plants/result.php?id_plant=ROPS

http://www.kew.org/plants-fungi/Robinia-pseudoacacia.htm

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