honey locust

The honey locust, Gleditsia triacanthos, can reach a height of 20–30 m (65–100 ft). They exhibit fast growth, but live a medium life span, as long as 125 years. The leaves are pinnately compound on older trees but bipinnately compound on vigorous young trees. The leaflets are 1.4–3.6 cm (1⁄2–1+1⁄2 in) long when compound and very slightly smaller when bipinnate. The leaves are green in summer and turn yellow in autumn in shades ranging from cream and tan to golden yellow. Honey locusts leaf out relatively late in spring, but generally slightly earlier than the black locust (Robinia pseudoacacia). The strongly scented flowers appear in late spring. Each cluster is a raceme 3–7 centimeters long with many tiny greenish-yellow to greenish-white flowers. The trees are polygamous-dioecious: many trees have only pollen producing flowers or seed producing flowers (strictly dioecious), but some will have both types of flowers in separate clusters, though usually one type will predominate. The fruit of the honey locust is a flat pod (a legume) that matures in early autumn and is often twisted or curved. The average size of the pods is 7–35 cm (3–14 in) long and 1.5–3 cm (1⁄2–1+1⁄4 in) wide. Once ripe the pod will contain as many as twenty dark brown oval seeds, each about 2 cm (1 in) long. Surrounding the seeds is a soft, gooey pulp with a slightly sweet flavor. …

The native range of the honey locust is widely agreed to be from northern Mexico through the Gulf Coast of the United States, northwards into the Midwest, parts of the US East Coast, and the southernmost parts of Canada. In Canada it is a rare forest species found in southern Ontario near Lake Huron, Ontario, or Erie. However, Plants of the World Online (POWO) lists it as introduced to Ontario while NatureServe and World Plants list it as native. It is listed as native to Nova Scotia by World Plants, but as introduced by POWO and not recorded by NatureServe. It is also recorded by NatureServe as growing as an introduced plant on Prince Edward Island. In the midwest it grows very widely in Illinois, Indiana, Ohio, and Missouri and is much rarer and scattered in Wisconsin, Minnesota, and North Dakota. In Kansas it grows naturally in the eastern half of the state, and at the eastern and northern edge of Nebraska along the Missouri River, a small area of South Dakota, and the southern portion of Michigan. In the eastern United States honey locust trees are regarded as native to Connecticut, Massachusetts, New Hampshire, Rhode Island, and New York. Though the botanist Elbert Luther Little showed the range as extending naturally into Pennsylvania, NatureServe list it as introduced to that state. …

The sweet pulp in honey locust seed pods is attractive as a food for many animals including cattle, deer, rabbits, squirrels, and hares. White-tailed deer are known to disperse the seeds of honey locust by consuming the pods and passing the seeds in their dung. It is likely that deer move the seeds over one kilometer from where they are eaten, though probably not more than three kilometers and aid the tree in reaching new habitats and maintaining its wild population even in fragmented habitats. The seeds themselves are consumed by crows in the winter. The size and number of thorns on the honey locust are thought to have evolved to protect the trees from browsing Pleistocene megafauna, including mastodons, which may also have been involved in seed dispersal. The seeds of the honey locust are resistant to sprouting without damage to the seed coat. In controlled experiments only 5% of the seeds sprout without treatment. In comparison, seeds soaked in concentrated sulfuric acid for one and a half hours increased germination to 68% and two and a half hours increases it to 98%. The honey locust moth (Syssphinx bicolor) feeds on honey locust and Kentucky coffee trees while a caterpillar. The first brood of the moths emerge from hibernation in the ground in the late spring. The green larvae have several horns on the backs and reach full size in about three weeks. …

The pulp on the inside of the pods is edible (unlike the black locust, which is toxic) and consumed by wildlife and livestock. Despite its name, the honey locust is not a significant honey plant. The name derives from the sweet taste of the legume pulp, which was used for food and traditional medicine by Native American people, and can also be used to make tea. The long pods, which eventually dry and ripen to brown or maroon, are surrounded by a tough, leathery skin that adheres strongly to the pulp within. The pulp—bright green in unripe pods—is strongly sweet, crisp and succulent in ripe pods. Dark brown tannin-rich beans are found in slots within the pulp. Likewise, its edible seed has nutritional potential, and the flour made from its cotyledons constitutes a food source with various potential uses for pastry and bakery, among other gastronomic uses.

Due to the honey locust's tolerance of urban problems such as salt spray, compacted soils, poor aeration, constrained planting areas, and pollution, it has been widely planted in cities. In addition it will adapt to relatively dry conditions and either alkaline or acidic soils. Once established it is also drought tolerant, though it grows best with good moisture. It was very widely planted as a replacement for American elm trees killed by Dutch elm disease, becoming somewhat overplanted in the 1970s. However, due to its wide planting many problems have been discovered. Like maples and oaks, honey locust is particularly vulnerable to Ganoderma root rots, a fungal infection of the roots and lower trunk of the tree. Three insects are the main pests that attack the honey locusts in urban areas, honeylocust plant bug (Blepharidopterus chlorionis), mimosa webworm (Homadaula anisocentra), and honeylocust spider mite (Platytetranychus multidigituli). Thornless cultivars are especially susceptible to damage by the Asian mimosa webworm. Though healthy trees are able to withstand one or two years of complete defoliation, stressed trees may be killed. The number of honey locust trees within 10 meters (33 ft) increases attacks by the webworms as does the amount of impermeable hardscape surfaces out to 20 m (66 ft) from a tree.

Cultivars. …