Maine Tree Species Fact Sheet

Common Name: Honeylocust (Sweet-locust, Thorny-locust)
Botanical Name: Gleditsia triacanthos  
Tree Type: Deciduous

Physical Description:

Growth Habit: Honeylocust is a moderately fast growing tree commonly found on moist bottomlands or limestone soils.  This species is deep rooted with a widely spreading and profusely branched root system and a strong taproot.  Because it is proven very hardy and tolerant of drought and salinity, it is widely planted for windbreaks and soil erosion control.  The leaves are alternate, pinnately or bipinnately compound, 4-8 inches long and have from 18-28 leaflets.  The margins of the leaflets are finely blunt-toothed.   The twigs are rather stout, smooth, glossy, and zigzag; usually bearing stiff, sharp-branched thorns from 3 to 4 inches long, above the leaf base (node).  Simple or usually 3 forked spines, 1½ -3 inches long or longer occur on the branches or trunk.  A thornless form, Gleditsia triacanthos var. inermis, is preferred in plantings.

 Height: Honeylocust reaches a height of 75 feet and a trunk diameter of 20 inches.

Shape: Honeylocust is usually a tree with a short trunk, and somewhat pendulous branches that form an open, broad, flat-topped head.  Its silhouette is very delicate and sophisticated

 Fruit/Seed Description/Dispersal Methods: The species is polygamo-dioecious (having male and female flowers on separate plants, but also having perfect flowers as well).  The flowers are borne in slender clusters of 2-2 1/2 inches long.  They appear in June when the leaves are fully-grown.  Honeylocust begins bearing seed at about ten years of age and the natural dispersal of seeds is not extensive.  The fruit is a shiny, reddish brown, flattened pod from 10 to 18 inches long.  The pod, which contains 10-20 brown oval seeds, is curved, with irregular wavy edges and often twisted.  The fleshy part of the pod is sweet, hence the name “Honeylocust.”  The seed pods ripen in late autumn and stay on the tree well into winter.  

Range Within Maine: Honeylocust is not native in Maine, but has been frequently planted in urban areas in the southern and central portions of the state.  This tree is hardy in Zones 4-9.

Distinguishing Features: The Honeylocust has branched, stout thorns; doubly compound leaves, with elliptical leaflets and  large, reddish brown seed pods.  The twigs are distinctly zigzag in shape.

Interesting Features: The wood of the Honeylocust is coarse grained, hard, and strong.  It is used for fence posts, crates, pallets, general construction and boat decking.  

Honeylocust is also a source of honey during the short flowering period in the spring.

Relationship to Wildlife: Cattle and hogs readily eat Honeylocust fruits.  Livestock also eat the young vegetative growth and snowshoe hares and cottontails eat both the fruit and plants.  Squirrels, deer, starlings, crows and opossum also eat the fruits.  

Landscape Use: In many urban areas, the thornless Honeylocust has been planted as a replacement for the American Elm.  Both the common Honeylocust and its thornless varieties are planted for erosion control and windbreaks.  Honeylocust has become overused in the landscape and in some urban areas.

Common Problems or Pests of the Tree in Maine: Honeylocust is a host for a number of leaf feeders (including webworms, spider mites leafhoppers, bagworms, Honeylocust plant bug, beetles, and walkingstick) and severe infestations can rapidly defoliate trees.  Other insect pests of this species are borers, scale, and the twig girdler.   The most noteworthy disease that affects the Honeylocust is an aggressive canker, Thyronectria austro-americana.

References:

Forest Trees of Maine, Twelfth Edition.  Maine Forest Service/Department of Conservation. 1995.

Know Your Trees. Cope, J.A. and Fred E. Winch, Jr. Cornell Cooperative Extension. 1992.

Manual of Woody Landscape Plants, 5th Edition.  Dirr, Michael A.  Publishing L.L.C. 1998.

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