Honeylocust (Gleditsia triacanthos)

A deciduous tree from the Bean Family (Fabaceae)

Honeylocust is found throughout all of Ohio, being a fairly common resident of fencerows and open fields, but achieving its most favorable growth on the downslopes of streams and floodplains of rivers, where the deeper soils are moist to wet. Its fine-textured foliage makes it stand out when found next to trees with larger leaves that block more sunlight. This native of the Mississippi, Ohio, and Tennessee River Valleys has its large trunks and zigzag twigs adorned with thorns like no other large tree, although most forms found in urban areas, parks, and arboreta are propagated from thornless varieties.

Thornless Honeylocust is commonly planted as a shade tree throughout the eastern United States and southern Canada, prized for its urban tolerance, near seedless character, and filtered shade.

While also known as Thorny Locust, Common Honeylocust, or Sweet Locust, the native form may grow to 80 feet tall by 50 feet wide, with a medium to rapid growth rate. As a member of the Bean Family, it is related to other Honeylocusts, plus Redbud, Kentucky Coffeetree, Black Locust, and Wisteria, among others.

Planting Requirements - Honeylocust is very adaptable to a wide range of soil types (organic, clay, sandy, or rocky), soil pHs (acidic, neutral, or alkaline) and moisture levels (wet, moist, or dry). It is noted for being extremely tolerant to many types of environmental stresses (summer heat, reflected light, sweeping winds, drought, flooding, poor soils, compacted soils, high pH soils, winter salt spray, winter salt deposition, and air pollution). Along with Green Ash, it is the most widely planted street tree in many urban areas. It grows in full sun to partial sun, and is found in zones 4 to 8.

Potential Problems - Several major pests (webworms, mites, galls, and borers) and a few pathogens (mostly trunk and root cankers) can cause significant problems to Honeylocust, especially when many trees are planted in close proximity to one another (monoculture conditions), facilitating the rapid spread of pests or diseases. Trees may be weakened over successive years by repeated infestations of pests, especially the webworms and the borers. The best solution is to mix plantings in rural or urban areas with other tree species, promoting diversity and diminishing the problems mentioned above.

Leaf Identification Features

A tremendous advantage of Honeylocust is the fragmented abscission of its small leaflets from the rachis in autumn, reducing the need for leaf cleanup in lawn areas.

In addition, Honeylocust has the added liabilities of significant surface roots and fallen fruit pods with age. Both of these situations can cause significant problems in urban areas, especially when heaving sidewalks and littering lawns. Fall color is often lackluster for Honeylocust, being green-yellow in most years, but golden-yellow in good years.

Other Identification Features

Honeylocust is noted for having both pinnately compound and bipinnately compound leaves (often on the same twig) arranged in alternate fashion along the zigzag twigs. The numerous small leaflets block out less sunlight than most other trees and therefore give "filtered shade" to the ground below.

Long, twisted pods characterize native Honeylocust, and mature from a lime color in summer to a reddish-brown color in early autumn, with some persisting on the tree into winter. Thornless Honeylocust usually has few if any fruits, and they tend to be shorter and have less pulp than their wild counterparts. However, in some years, some Thornless Honeylocusts are loaded with fruit pods.

Honeylocust is a polygamo-dioecious species (that is, male and female flowers occur on separate trees, but all trees have perfect flowers as well), and as a result some trees tend to bear fruit much more heavily than others. The flowers emerge with the expanding foliage in mid-spring and are not showy, but attract bees due to their abundant nectar. An immature male flower is shown.

Honeylocust is noted for its three-pronged, thick thorns on its lower twigs, and its long, compound thorns on its trunks and major branches. Its young bark tends to be smooth with numerous lenticels, while its mature bark develops flared fissures that run lengthwise along the single or multiple trunks. Large trees have flared bases that merge with the numerous surface roots.