Honey Locusts
What's that, honey?
Two types of people generally recognize honey locust (Gleditsia triacanthos); urbanites whose cities’ sidewalks are littered with the unique leaves and occasional pods and then those with memories of honey locust spikes bludgeoning through a tire or an unfortunate shoe. Before modern times, the anachronistic honey locust likely relied on Pleistocene megafauna to expand its range, similar to the Kentucky coffee tree. It occupied open and often rocky, dry upland areas east of the Rockies prior to human settlement. As these animals faced extinction, they were left behind with the apes who covered the continent of North America and found new uses for the tree, from the sugary pulp to the unique thorns themselves.
The historical use of honey locusts in academic writing is quite limited, and its management by Indigenous people is even more limited. Dr. Robert Warren, a guest on the podcast, has proposed that, despite wet regions being ill-suited spots for honey locusts, the Cherokee cultivated them in these regions, which has left a “cultivation legacy” in its distribution patterns similar to the modern distribution of another anachronistic tree, the Kentucky coffee tree. The question remains: why?
We’ve talked about anachronistic trees such as the Kentucky coffee tree and pawpaw, species that co-evolved with other animals and other entire ecosystems that no longer exist, and honey locusts that are no different. However, a small piece of history has survived alongside the honey locust, which is the honey locust moth. Now, what makes this moth particularly special is that it feeds specifically on the Kentucky coffee trees as a caterpillar and on the honey locust as a moth, connecting these two otherwise forgotten species to one another through one small chain.1 The moth doesn’t use any other trees for feeding; it may have fed on several species that no longer exist. These two trees are solely responsible for their continued survival.
As stated previously, these trees appear to follow Cherokee settlements, including several disjunct populations of honey locusts. The honey locust is of particular value because of the sugary pulp inside of the locust pods. Too far south for maple syrup, these trees offered a reliable, perennial source of sugar.
However, how that sugar was processed seems to have been lost to history. We do have some ideas based on how Indigenous groups harvest similar pod foods and how the Appalachians have processed honey locusts in recent memory. It’s worth noting that first, there’s limited evidence of storage, suggesting that the sugar was primarily consumed fresh.
The first method of consumption aligns with the little written evidence, which is that the pulp was scraped out of the pods and consumed directly. This would make the pod sugar more of a treat than a staple in Cherokee diets. Alternatively, it’s possible the pods were boiled, and the sugar was mixed into a syrup that could be further boiled and granulated, similar to maple sugar. From experience, this liquid tends to be very sweet but also extremely tannic. However, anecdotally, selected honey locust varieties seem to leave less residual tannin in the liquid.
Processing them this way is simple—cut the edge away from the seeds (where most of the gum/sugar is) and boil while mashing until the water is cloudy and thick with pulp. Then, take the pods out and drain them through a cheesecloth. The remaining mush is what you’re looking to utilize. This pulp's flavor is an interesting mix of overripe banana and cacao. The pulp can be dehydrated into fruit leather as well, and anecdotally, it may be possible to break it down further for a more shelf-stable, granular sugar.
Honey locust was also often mixed with persimmon for consumption. In Appalachian culture, honey locust pods are mixed with persimmon to make a fermented beer-esque drink. We have honey locust beer mentioned in passing in John Filson’s writing when exploring modern Kentucky, but little more is said (he also describes the ‘good’ coffee of the Kentucky Coffee Tree, so some care should be given before taking his words at face value).2 Given the overlapping ecosystems, it’s unsurprising that honey locust and persimmon are used together. However, it wasn’t just the pods that was of use. Its wood is good for heating, and the limbs of the tree were used for weapons due to its strong wood. One Cherokee settlement was even named “Kulsetsiyi”, meaning “honey locust place”.
Honey locust’s first major foray as a potential tree crop came from J.Russell Smith’s work describing them in his book “Tree Crops,” which was put into practice by John Hershey’s work with the Tennessee Valley Authority (TVA), improving eroded lands in the Tennessee Valley (and furthermore through competitions sponsored by the American Genetic Association to find improved selections). The competitions drew entries from 36 states, with a wide variation in pod characteristics. The best pods, generally speaking, came from trees in the south.
The first competition produced held by the Journal of Heredity has received less attention than the competition responsible for much of the genetics we think of when it comes to honey locusts today, but good selections were found in this competition as well, including Goldworth (the first prize, from Villa Rica, Georgia) and Diden (fourth place, from Glen Mary Tennessee).3 The first major competition was in 1934. The Southern Agriculturalist, a regional magazine, advertised the competition for the TVA, yet despite high interest, only 17 entries were actually submitted for judging. The three winners were:
First Place
Name: L.H. Calhoun
Origin: Gadsden, Alabama
Sugar content: 36.45% (however, Hershey cites sugar content at 32.84% in competition)
Pod length: 14 inches
Pods per lb: 17
Second Place
Name: J.A. Torbett
Origin: Rhea County, Tennessee
Sugar content: 34.3%
Pod length: 13.5 inches
Pods per lb: 21
Third Place
Name: Dave Millwood
Origin: Lake Junuluska, North Carolina.
Sugar content: 31.2% (again, in Hershey’s notes, he cites sugar content at 28.18%)
Pod length: 15 inches
Pods per lb: 13
Today, ‘Millwood’ and ‘Calhoun’ are well-known in tree crop circles, but ‘Torbett’ is largely absent. This is because the first two are comparatively thornless, while the latter was a very thorny tree.
More contests continued through the late 1930s, but no trees showing significant improvements were discovered. That’s not to say the competitions were fruitless. New varieties were found with fruit clustering and unusually thick pods, which were propagated on a limited basis for future breeding and have since been largely lost.
The TVA worked to study the various utility of honey locust pods, from the sugars for human consumption to the feed value of pods for livestock and its use for ethanol production. They found that calves and rats were able to consume and thrive on honey locust meal (as opposed to corn meal) and found that, while slightly less efficient, it proved to be a viable food source— and these studies were done with common pods, not improved selections. Further, pods were substituted for oats on a dairy farm, and there was no drop in milk production over two years, highlighting their strong nutritional value.4
Additionally, studies showed that the pods' sugar content was very suitable for ethanol fermentation, putting marginal farmlands to use with a native crop. This research has continued today and is quite promising (more on this later).
The TVA also began working to breed improved selections, starting with the winners of the competition above. In 1933 and 1939, research was done to better understand cross-pollination, and they found that there was very little incompatibility. This meant that future breeding work would produce significant viable seeds, and controlled breeding of selected honey locusts would be feasible. In short, honey locusts would be a (relatively) easy tree to work with for breeding.
In 1939 & 1940, work was done to identify if scionwood from trees would carry its thorny traits. What they found was that thorny scionwood would become thornless after grafting 18% percent of the time, partly thorny would become thornless over 50% of the time, and thornless scionwood would produce thorny trees less than 4% of the time. What this meant was that selections of improved trees, even if thorny, could be propagated as thornless clones using scion wood from branches that had ceased thorn production.5 The takeaway is thorniness is not a significant factor in identifying selections for future use.
During this same period, John Hershey was busy drafting a book on honey locust research, which unfortunately was never finished before he died. Fortunately, Greg Williams stored the drafts, and together with Zach Elfers, we’ve made this draft available here. In his drafts, he describes stories of roasted seeds and fermented pod drinks for human consumption.
John also goes into detail about the research the TVA was doing with Honey Locusts, including grinding the pods whole, and that the pod shell is what carried most of the bitterness. The “fine powdery dust” that remained in this grinding process contained the “strongest flavor of sugar and the least bitter.” They trialed making muffins with a mix of yellow corn and Millwood honey locust (at a 2:1 ratio), which he described as tasting “fine,” with some consumers describing the muffins as surprisingly “too sweet.”
He concluded that honey locusts offered crop yields above corn when working with improved selections—specifically Millwood—as livestock feed, although the pods had the potential for human consumption as well.
After World War 2, interest waned. However, researchers overseas continued to study the plant as a resource for submarginal farmlands. As the American breadbasket outperformed on a global stage, American agriculture was shipped around the world, and interest in marginal crops like the honey locust was lost. Many of the ongoing honey locust pasture programs were discontinued, including many of the fields managed by the TVA. However, rogue populations continued to survive into the 1970s. This mentality began to shift again as the oil embargo of 1973 forced a re-evaluation of the input-output costs of our farming systems (and pushed the Odum Brothers into the limelight).
The 1970s saw a rebirth in alternative agriculture systems globally, even if the ideas of Americans like J. Russell Smith were ignored at home. In 1979, Dr. James Hanover of Michigan State University picked up where Smith left off, looking to provide more insight into the species' variation. While Hanover worked with honey locusts, his focus was more broadly on biomass production for energy. In 1974, he founded the Michigan Cooperative Tree Improvement Program, which brought together several stakeholders to work on tree breeding, specifically around poplar, aspen, and black locust, and oversaw large-scale black locust breeding.6 However, despite a successful career with trees, honey locust rarely shows up again in any of his research, except in passing in regards to Smith’s work.7
Much of the work around tree crops, in general, during this period was focused on energy production, similar to the Sunchokes and the American Energy Farming Systems, which invested heavily in a future powered by perennial ethanol. In this way, Hanover’s research isn’t surprising. He did, however, oversee a range-wide collection of honey locust seeds. While no formal papers seem to exist to highlight more details, from what scant evidence exists, it appears that he was looking to understand the genetic and phenotypic variations in honey locusts across their natural range.
While little institutional work has been done in recent years on honey locusts for human food, the seed has been studied as a partial replacement for fish meal when raising carp in fish farms. In a recirculation system, carp were fed up to 30% of their feed as honey locust seed. Up to 20% showed no difference to fish meal, which offers a way to utilize the seed, which is often not considered to be edible for humans.8 The flowers of the honey locust are also promising; recent studies have identified new esters, and the extracts have shown anti-inflammatory activity “superior to aspirin and comparable to other over-the-counter non-steroidal anti-inflammatory aids naproxen & ibuprofen.9
While we have largely focused on the sugars of the honey locust pods, researchers like Eric Toensmeier are finding ways to utilize the beans themselves. Following John Hershey’s research, they are grinding them into flour and turning them into tofu. Work continues to find ways to convert the calories produced on these trees into viable, scalable food products for the general public.
Today, the primary selections of honey locusts for pod production are Ashworth, Calhoun, Hershey, Big Fatty, and Millwood. Ashworth is a selection made by John Hershey from a tree found in New York with 30+% sugar content and a melon-like flavor. Hershey is another selection made by John Hershey, although its origin seems to be lost to history (some websites refer to the contests for this selection, but I doubt this to be true). Big fatty is another cultivar that originated from John Hershey’s Nursery and was selected by Zach Elfers due to its uniquely fleshy pods. Zach’s Nursery has a number of improved selections that don’t seem to be found anywhere else and a place I’d highly recommend grabbing improved genetics from.
Lastly, there have been reports of some reactions to the pods when used in cooking. It seems to be isolated and could be due to the diversity in wild genetics, but it’s worth noting for allergen-prone folks. The reports seem to be consistently tied to the thornless selections used in landscaping, which fall under “inermis” (for example, Gleditsia triacantos inermis ‘skyline’). We haven’t explored the selections developed for urban landscaping, but given these trees' capacity to handle poor soils and occasional flooding, their role as an urban tree shouldn’t be surprising. All said the honey locust seems, despite its anachronistic existence, well-suited for human-led environments and demands that we reconsider our relationship with it in the Anthropocene.
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Wagner, David L. (2005). Caterpillars of Eastern North America. Princeton, NJ: Princeton University Press. ISBN 0-691-12144-3.Tree crops for energy co-production on farms. (1981). . (National Technical Information Service, U.S. Dept. of Commerce). https://www.osti.gov/servlets/purl/6578611#page=29
Filson, John. The Discovery, Settlement and Present State of Kentucke.
https://auf.isa-arbor.com/content/9/9/248
Atkins, 0. A. 1942. Yield and sugar content of selected thornless honeylocust. Ala. Agr. Exp. Stn. 53rd Ann. Report:25-26
Warner, John and Clarence Chase, 1956. The Timber Resource of North Dakota. USDA-Forest Service. North Central Forest Experi ment Station Paper No. 36. St. Paul, Minnesota
Northeastern Forest and Conservation Nursery Association Meeting, Grand Rapids, Michigan, July 20 to 23, 2009.
Gold, M. A., & Hanover, J. W. (1987). Agroforestry systems for the temperate zone. Agroforestry Systems, 5(2), 109–121. doi:10.1007/bf00047516
Buyukcapar, H. M., Gunlemez, F., & Kamalak, A. (2011). Effect of partially replacing fish meal with honey locust seed (Gleditsia triacanthos) on growth, feed utilisation and body composition of mirror carp, Cyprinus carpio, fingerlings. Journal of Applied Animal Research, 40(1), 8–12. https://doi.org/10.1080/09712119.2011.607761
Chuan-Rui Zhang, Amila A. Dissanayake, Muraleedharan G. Nair, “Functional food property of honey locust (Gleditsia triacanthos) flowers,” Journal of Functional Foods, Volume 18, Part A, 2015, https://doi.org/10.1016/j.jff.2015.07.012.
Will this one be uploaded to Apple Podcasts? My apologies if it’s just me that can’t find it