Native Honeylocust is October Tree of the Month

Native Honeylocust at Deer Run Forest Preserve is October Tree of the Month

NLI’s Legacy Tree Program

NLI’s Legacy Tree Program is pleased to announce the 2025 October Tree of the Month is a native Honeylocust (Gleditsia triacanthos), located at Deer Run Forest Preserve, 5691 River Rd., Cherry Valley, Ill. 61016. It’s located near the entrance of the preserve, but hard to get close to in the growing season. The height of this tree is 76 feet, with an average crown spread of 71.5 feet, and a trunk circumference of 150.6 inches.

This very large Honeylocust was nominated by Alan Branhagen, Executive Director of Natural Land Institute (NLI). Branhagen said, “I often hike at Deer Run Forest Preserve to get a nature fix among its many magnificent and diverse trees. I thought it was the largest Honeylocust I had ever seen and its measurements reveal it is likely the new Illinois state champion.” Branhagen, a naturalist and gardener, thinks Honeylocusts are a great tree for all the ecosystem services they provide – many caterpillars to feed songbird nestlings, flowers for pollinators and strong branching resilient to recent storms. One of his favorite moths, the friendly (often lands on one’s bare skin and sips sweat) and day-flying Orange Wing, is a specialist on this tree (its caterpillars will feed on no other plant). There are several other unique moths that specialize on this tree.

Honeylocust is a native tree that is often reviled in the wild for its often-wicked thorns (capable  of puncturing a tire or sole of one’s shoe) – while thornless trees are favored in the landscape.  The tree is rugged with tough, plated bark and a relatively horizontal crown reminiscent to the acacia trees on the African plains one sees in nature programs – yes, it is related to the Acacia and had a similar niche! The leaves are special: doubly compound in a rich herringbone pattern comprised of small leaflets. They are a no rake tree though the leaflet’s fine stems (rachises) drop in the fall too. They make good garden and landscape trees because they are tolerant of disturbed soils, have deep roots and cast a light shade that many plants can thrive beneath. Honeylocusts are also in the legume family so fix nitrogen to the soil, providing their own fertilizer.

The fruits of Honeylocust are long, helical bean pods. Preferred fodder for deer or domestic chickens and cattle. The fruits are only produced on female trees and often in abundance where they are considered messy – thus landscape cultivars are clones of thornless male trees! The flowers are in clusters and not very showy but always abuzz with lots of pollinators seeking the nectar and pollen – even on the male trees. For all the aforementioned reasons, Honeylocusts are planted in food forests and part of permaculture landscapes.

The reason why most Honeylocusts have wicked thorns is that the thorns protected the tree from the now extinct megafauna – allowing the fruits to mature and drop (the young pods are edible to humans too). The fallen fruits, containing mature seeds, would be eaten and dispersed in the dung of whoever ate them. That’s why so many pastures have Honeylocusts as cattle do a good job of dispersing this tree. The thorns make the tree a good tree for songbirds to nest in, protected from nest predators. Very large old trees like this legacy tree often have no reason to grow thorns anymore as the trunk’s thick bark protects the tree while the high canopy of fruits is out of reach. As there is now over 10,000 years without mammoths, mastadons and giant ground sloths, and people prefer the thornless trees; the future Honeylocust will likely no longer produce thorns.

The public is invited to attend the Legacy Tree Hike on Sat., Oct. 18, 2025, 1:30 p.m. at Deer Run Forest Preserve, where Alan Branhagen will lead a hike to showcase the October Tree of the Month, the Honeylocust, as well as talk about the many other notable trees at this preserve. The hike is free with registration required at https://www.winnebagoforest.org.

Background and For More Information:

Natural Land Institute launched the Legacy Tree Program in January 2024. Anyone may nominate a tree on private or public land from NLI’s 12 county region. To see monthly stories, for more information and a nomination form visit: https://www.naturalland.org/nlis-legacy-tree-program-january/ or call 815/964-6666. NLI, an accredited land trust, is a 501(c)3, not-for-profit land conservation organization based in Rockford, IL and has protected 19,000 acres of natural land in Illinois since 1958. NLI’s mission is to create an enduring legacy of natural land in northern Illinois for people, plants and animals. For more information and to donate visit: www.NaturalLand.org.