Locust trees are all species that belong in the genera Gleditsia or Robinia. The genus of Gleditsia is made up of 12 species of Locust trees including Taubert, Water locust, Forbes & Hemsely, Caspian locust, Franchet, Merr, Japanese honey locust, Isely, Chinese honey locust, Honey locust and Thornless honey locust. Texas Honey locust is a hybrid species of the same genus. Gleditsia sinesis or the Chinese honey locust is used in medicine as one of the 50 fundamental herbs which are used in Chinese herbology. Caspian Locust of Persian Honey locust is a well known Gleditsia species. This locust tree is native to western Asia, int he caucasus region of Azerbaijan and northern Iran. Caspian locust is a deciduous tree which grows up to 12 meters tall. The leaves are pinnate and are about 25 cm long with up to 20 leaflets. The flowers are green and 10 cm long. This species is related to the Japanese honey locust and it is even treated as a subspecies by some botanists.
Robinia species are commonly known as locust trees. Robinia is made of flowering plants in the family Fabaceae which is native to North America and North Mexico. These trees and shrubs can grow anywhere from 4 to 25 meters tall. The leaces are pinnate with oval leaflets. The flowers are pink or white. Most Robinia species have thorny shoots, while a few of them have sticky hairs on the shoots. There are 10 species in the genus of Robinia including Robinia boyntonii, Robinia elliottii, Robinia hartwegii, Robinia hispida ( Bristly locust), Robinia kelseyi, Robinia luxurians, Robinia nana, Robinia neomexicana ( New Mexican locust) Robinia Pseudoacacia ( Black locust of False Acacia), and Robinia viscosa ( Clammy Locust). There are also several natural hybrids including Idaho locust and three others which are less known.
Bristly Locust belongs to the genus of Robinia. It is also known as Rose acacia or Rose locust. This shrub or small is native to the southeastern United States and is a well known tree. Bristly Locust grows up to 4 meters tall. The leaves are anywhere from 12 to 23 cm long. The flowers are pink and are produced on short racemes of up to 12 flowers which are about 1 inch in diametes. New Mexican Locust is another well known tree. It is found in southwestern United States and northern Mexico. It grows from 5 to 10 meters tall and has bristly shoots. The leaves are around 15 cm long with 7 to 15 leaflets which have a pair of sharp red thorns. The flowers are white or pink and are produced in spring and early summer. This locust tree is used as food by some Pueblo Native Americans in New Mexico. Squirrels and quail eat the locust’s seeds. Locust trees come in different sizes and varietes to choose from. In the United States, some of the most known and used locusts include Shademaster Honey Locust, Thornless Hone Locust, Black Locust and Sunburst Honey Locust.