Black Locust

Basic Information
Tree ID: 
201
Family: 
Genus and species: 
Description: 
This Black Locust Tree is found across Prospect Street from Sterling Chemistry Laboratory, and just up the hill from Ingalls Ice Rink. If you were a squirrel that lived in this tree, you would be able to see students walking to their laboratory classes in the morning and fans coming to cheer for the Yale hockey team in the evening. At lunchtime, you might even be able to smell the delicious scents of Thai and Mexican food from the food trucks by the intersection of Sachem and Prospect. At almost 70 feet tall, this particular Black Locust tree would give you an excellent bird's-eye view of campus. Despite its size, the Black Locust is actually a member of the pea family, Fabaceae. Black Locust trees produce fragrant flowers and pea pod-shaped fruits. While they are flexible with regards to soil type, and can grow in a variety of locations, Black Locust trees do require plentiful sunlight and open ground. Black Locust trees can be found throughout all of the United States except Alaska and Hawaii, as well as parts of Canada, Asia, Europe, and southern Africa. However, their normal range is limited to the southeastern United States. Black Locusts are valued for the honey produced from their flowers as well as its durable wood. However, this tree can become invasive due to its ability to produce large quantities of seeds and reproduce via root suckers.
Surveyors: 
Hannah Rubin and Usman Khalid
Location
Collected Data
Tree shape: 
Irregular
Date of tree entry: 
02/04/2026
Height: 
20.82 m
Diameter at breast height: 
0.58 m

Bark
Twigs & branches
Black Locust twigs are either smooth or possess fine hairs. However, these twigs are also armed with pairs of spines at the base of each leaf. These spines, which are considered modified stipules, can also be found on the limbs and trunks of younger trees.
Reproductive Structures
Black Locust trees flower between late April and early June depending on location. The flowers hang from the branches in long, axillary clusters 10 - 20 centimeters long. The flowers, white and fragrant, are about 2 centimeters long. The upper petal has a yellow spot on it. The fruit of the Black Locust is a dry, dark brown legume that resembles a pea pod. The fruits are 5 - 10 centimeters long and very thin. They split open to release their seeds.
Seasons
  • Winter
  • Spring
  • Summer
  • Autumn
Research
Origin, history, and uses: 

The typical range of the Black Locust extends from the southern Appalachian mountains to the Ozark mountains of southern Missouri and parts of Arkansas and Oklahoma. However, it has also been planted in southern Canada, most of the United States, and abroad. The Black Locust is not a native species in Connecticut, and likely made its way here after being planted for specific purposes, such as erosion control or to use its wood.

Black Locust wood is considered to be one of the strongest woods in North America. It can be used for fence posts and ladder rungs, and it was also used for railroad ties before the days of modern wood preservation. Black Locust wood weighs 48.2 pounds per cubic foot, which is similar to the weight of oak wood.

The honey of Black Locust trees is prized for its fruity flavor and enticing fragrance. Unlike the honey commonly sold in stores, the color of Black Locust honey is clear white, pale yellow, or yellowish green. Black Locust bark was used by indigenous people as an emetic and to reduce toothache. The roots of a Black Locust tree contain nodules of nitrogen-fixing bacteria, so Black Locust trees were historically planted on old strip mines to restore the soil quality.

Several insects feed on the sap, leaves, and wood of the Black Locust. Some insects, such as Carpenterworms and Treehoppers, may not cause extensive harm to healthy trees. Others, such as Locust Leaf Miners and Bagworms, can stunt growth or cause loss of foliage. The Black Locust does not grow well in poorly drained soil or shady conditions, and its wood is susceptible to ice damage.

 
Shrub Canopy Area: 
128.68sq.m.

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