General Description

This fast growing, hardwood deciduous tree can reach 40-100 feet, and can live for up to 100 years.

Flower Description

Flowers grow in large, drooping, flower clusters that can be up to 10 inches long. Each individual flower in this cluster is white or cream colored, and is a typical pea-family shaped flower: a keel-shape of 2 petals at the bottom, two vaguely spoon-shaped petals on top of the keel, and petal forming a "banner" at the top.

Leaf description

The light green leaves are divided into 9 to 19 oval-shaped leaflets. 

Stem description

Young bark starts smooth and green-brown and ages to grey and dark brown as it ages and forms deep fissures and grooves. Stems grow long, sturdy, sharp spines/thorns, which can be up to an inch long. These spines are often retained on older branches, but typically are not seen on fully mature trunks.

Fruit Seed Description

A flattened peapod which will start green-red and ripen to brown as it hardens with 2 to 15 flattened seeds inside.

May Be Confused With

Tree-of-heaven (Ailanthus altissima) also have drooping bunches of white flowers, but tree-of-heaven flowers are much smaller and look more like stars than like pea flowers. Tree-of-heaven leaflets have pointed tips and small glands on the bases.

Honey locust (Gleditsia triacanthos) only grow in a few locations in South East Washington. Honey locust leaflets have pointed tips.

Ashes (Fraxinus sp.) leaflets have pointed tips and are generally much larger than black locust leaflets. Ash flowers are pale green-yellow drooping catkins, and not showy flowers. The seeds are papery samaras (winged seeds) with only one seed per fruit.

Mountain ashes (Sorbus sp.) leaflets have serrated edges. Their flowers have 5 white petals, and are generally small. The fruits are round, hard, frequently orange and red, berries. When fully grown, they are only the size of a small tree.

Elderberries (Sambucus sp.) leaflets have serrated edges. Their tight bunches of flowers are composed of many small 5-petaled flowers. They produce small blue, black, and red berries, depending on species. When fully grown, they are usually only the size of a large shrub.

Sumacs (Rhus sp.) leaflets have serrated edges. They grow tight cones of flowers, and the fruits are very small and generally red. When fully grown, they are usually shrub sized.

Walnuts (Juglans sp.) leaflets are generally very lightly serrated, and have pointed tips. The flowers are dangling green catkins, and the fruits are large, hard, rounded, walnuts that start green and age to brown or black.