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// SPECIES PROFILE · TREE · NATIVE · LEGUME

Honey Locust

Gleditsia triacanthos

Honey Locust is the native thorny legume of NE Oklahoma bottomlands — a fast-growing, deep-rooted, drought- and salt-tolerant shade tree whose thornless cultivars (especially 'Skyline', 'Shademaster', 'Imperial' and 'Sunburst') have become arguably the most-planted street tree in Tulsa since the loss of the American elm. The wild form is armed with branching 3-pronged thorns up to 8 in long and drops huge curved seedpods that ferment with sweet pulp — a megafauna anachronism awaiting mastodons that no longer come.

// QUICK FACTS
Family
Fabaceae (legume family) — subfamily Caesalpinioideae
Native range
Central US: PA & NY → IA → KS → TX → AL
USDA hardiness
Zones 3–9 (Tulsa = 7a/7b)
Mature size
60–80 ft tall × 60–80 ft wide
Crown
Open, spreading, vase- to umbrella-shaped
Lifespan
~120 yrs typical; some to 200+
Sex
Polygamo-dioecious (mostly separate-sex trees)
Bloom
Late May – early June; small, fragrant, pale green
Fruit ripe
Sept–Nov; long curved purple-brown pods
Sun
Full sun
Soil
Highly adaptable — clay, sand, alkaline, urban; pH 5.5–8.0
Water
Drought-tolerant; tolerates short flooding
Nitrogen fixer
Very limited — lacks effective rhizobial nodulation
Wildlife
Deer, livestock, squirrels, songbirds, bobwhite
Honey Locust (Gleditsia triacanthos) — fine pinnate foliage and broad open crown
Gleditsia triacanthos — pinnately compound foliage and the open, dappled crown that made the thornless cultivars America's favorite street tree of the late 20th century. Photo via Wikipedia / Wikimedia Commons.

Identification

[ field key — thorns · foliage · pods · bark · lookalikes ]

Habit & bark

A medium to large deciduous tree, typically 60–80 ft tall in NE Oklahoma with an open, broad, vase-shaped crown that casts famously light, dappled shade — lawn grass grows under it where almost nothing else can. Bark on young trees is smooth and grey- brown; mature trunks become deeply furrowed into long, rough, plate-like ridges with curling edges. The fast growth, the open crown, and the small leaflets all combine to give the tree its airy silhouette.

Thorns — the diagnostic

Wild trees are armed with the most spectacular thorns of any North American tree: stout, branched, often 3-pronged, dark red-brown, and 3–8 in long, growing in dense clusters from the trunk and main branches and singly along smaller limbs. The thorns are modified stems and arise from leaf axils. Thornless cultivars are grafted from naturally-occurring thornless individuals (var. inermis) and are the only forms used in modern landscape work.

Foliage

Alternate, deciduous, mostly bipinnately compound (occasionally just pinnate on vigorous shoots), 6–8 in long with 14–30 small (~¾ in) oblong-elliptic leaflets that are a bright fresh green in spring and a clean clear yellow in fall. The leaflets drop tidily, breaking down quickly — a feature that endeared thornless cultivars to mid-century urban-tree planners replacing American elm.

Pods, flowers & lookalikes

Flowers are tiny, pale yellow-green, very fragrant, in 2–3 in drooping racemes — loved by honeybees but easy to miss visually. Female trees produce dramatic flat, curved, twisted, purple-brown pods 6–18 in long filled with hard seeds in a sticky-sweet pulp. Confusables: Robinia pseudoacacia (black locust) has paired stipular spines (not branched), showy white flowers, and short straight pods; Gymnocladus dioicus (Kentucky coffeetree) has even larger pods but no thorns and bipinnate foliage; the SE coastal-plain native Gleditsia aquatica (waterlocust) has much smaller pods.

Habitat & Range in NE Oklahoma

Gleditsia triacanthos is native to the rich alluvial soils of the central US, with NE Oklahoma squarely inside the heart of its natural range. Wild populations occupy the floodplains, river terraces, and slope-bottom woods of the Arkansas, Verdigris, Caney, Neosho, Illinois, and Grand rivers, and the rich-soil cove forests of the Ozarks of Cherokee, Adair, and Delaware counties. It is also a major component of old pasture "honey-locust thickets": dense, thorny stands that develop on overgrazed bottomland where cattle have refused to push through and seeds dropped in dung germinate readily.

The species is famously tough urban-tree material. It tolerates compacted soil, road salt, drought, alkaline pH, and air pollution, which is why Tulsa's planted street-tree inventory after the loss of American elm in the 1960s–70s skewed heavily toward thornless honey-locust cultivars (along with Pyrus calleryana 'Bradford' — a choice we now regret). Honey locust hangs on as a major street tree throughout midtown Tulsa, the University of Tulsa, downtown, and most municipal park plantings, and is widely recommended for parking-lot, median, and small-yard use across the region.

Ecology & Wildlife Value

[ megafauna anachronism · livestock fodder · pollinators · pests ]

The megafauna seed-dispersal story

The huge sweet pods, the vicious branching trunk thorns, and the hard impervious seed coat are textbook features of a "megafauna anachronism" — a plant whose seed-dispersal partners (mastodons, giant ground sloths, gomphotheres) went extinct in the Pleistocene ~10,000 years ago. The thorns deterred Pleistocene megaherbivores from stripping the trunk; the pods were swallowed whole; gut passage scarified the seed and deposited it in a pile of fertilizer. Today the role is filled poorly by deer, livestock, squirrels, and humans — which is why wild honey-locust regeneration is heaviest where cattle eat the pods.

Livestock fodder & food for wildlife

The pods contain ~10–30% sucrose in a thick pulp and are eagerly eaten by cattle, hogs, deer, raccoons, opossums, fox squirrels, and bobwhite quail. They drop in fall and persist into winter as one of the most important mast resources of NE Oklahoma bottomland. White-tailed deer will paw through snow to reach them. Some agroforestry researchers (Wes Jackson at the Land Institute, Mark Shepard, and others) have studied select-pod honey-locust as a perennial protein-and-sugar fodder crop comparable to carob.

Pollinators

Honey locust is a strong honey-bee plant — bees work the small fragrant flowers heavily during the late-May/early-June bloom. The honey is light and mild. Native bees (Halictus, Lasioglossum, Bombus) and a long list of small flies also visit. Despite the family, honey-locust is not a major nitrogen fixer — unlike most legumes it lacks effective rhizobial nodulation and operates as a normal forest tree nutritionally.

Pests & diseases

Modern landscape honey-locusts have a real pest list, mostly cosmetic: honeylocust plant bug and spider mite cause early-summer leaf scorch in hot dry years; mimosa webworm (Homadaula anisocentra) skeletonizes leaves; honeylocust pod gall midge distorts new growth; thyronectria canker is a more serious bark disease in stressed trees. The real ecological cost is monoculture: planting honey-locust as 30%+ of a city's street-tree inventory invites pest outbreaks the way American elm did before Dutch elm disease.

Thorns are dangerous: Wild honey-locust thorns can puncture car tires, work boots, and farm equipment. They also cause persistent stab wounds that can become infected (Clostridium and Staphylococcus). Wear leather gloves and heavy soles when working in or removing wild stands. Branches and dropped twigs stay sharp on the ground for years.
Diversify, don't monoculture: Tulsa's experience with Pyrus calleryana and earlier with American elm should teach restraint. Even a tree as urban-tough as thornless honey-locust should be limited to ~5–10% of any neighborhood street-tree palette to keep pest and disease risk manageable.

Horticulture & Care

[ siting · cultivar selection · planting · pruning · pests ]

When to plant intentionally

Thornless, podless honey-locust cultivars are excellent choices for: street trees, parking-lot islands, parkway plantings, small back yards (light shade lets a lawn grow under it), and tough urban infill sites. Avoid planting near apple-orchard or sensitive crop areas where pollen and pests overlap. Wild seed-grown trees with thorns belong only on rural pasture / wildlife properties where the thorns and pods are an asset, not a liability.

Choose a male, thornless cultivar

For any urban or suburban planting, choose a thornless cultivar (var. inermis) selected for its male / podless habit so you do not have a 12-month cleanup of foot-long sticky pods. The cultivars below are all on the OSU Extension and the Society of Municipal Arborists' approved tree lists for Tulsa-zone use.

Planting & establishment

Pruning

Honey locust forms strong wood and is generally well-structured, but young trees often grow with multiple competing co-dominant leaders that should be pruned to a single central leader during the first 5–10 years. Prune in late winter (Feb–early March), before bud break. Avoid pruning during the active growing season — honey-locust wounds heal slowly and invite canker.

Notable cultivars for NE Oklahoma

Cultivar Habit / sex Distinguishing feature Notes for Tulsa
'Skyline' Pyramidal · seedless Strong central leader; uniform pyramidal crown Best structural choice for street use; the standard Tulsa municipal-tree pick.
'Shademaster' Upright, vase-shaped · seedless Symmetrical vase form; deep green foliage; very fast Excellent residential / parkway tree; arguably the most planted in midtown Tulsa.
'Imperial' Compact, rounded · seedless Smaller (~35–45 ft); more rounded crown Good choice for smaller urban yards and constrained sites.
'Sunburst' Upright, broad · mostly seedless Bright golden-yellow new growth, fading to green by midsummer Ornamental specimen tree; full sun for best color; less vigorous.
'Moraine' Vase-shaped · podless & thornless The original 1949 thornless / podless introduction Classic; harder to source today, supplanted by 'Skyline' and 'Shademaster'.
'Street Keeper' Narrow upright · seedless Distinctly columnar — ~45 ft tall × 20 ft wide Excellent for narrow streets and tight rights-of-way.

Pests & diseases

Cultural & Material Uses

Honey locust has a useful but quieter cultural record than oak or walnut, mostly tied to its hard rot-resistant heartwood, its sugar-rich pods, and its thorns.

Sources & Further Reading

  • USDA NRCS PLANTS Database — Gleditsia triacanthos: plants.usda.gov/plant-profile/GLTR
  • USDA Forest Service Silvics of North America, Vol. 2 (Hardwoods) — Blair, R.M. (1990), Gleditsia triacanthos: srs.fs.usda.gov/pubs/misc/ag_654 — gleditsia/triacanthos
  • USDA Forest Service Fire Effects Information System (FEIS) — Gleditsia triacanthos.
  • Lady Bird Johnson Wildflower Center — Gleditsia triacanthos: wildflower.org — GLTR
  • Missouri Botanical Garden Plant Finder — honey-locust cultivar profiles.
  • Oklahoma State University Extension — Trees for Oklahoma Landscapes and Selecting Street Trees for Oklahoma.
  • Janzen, D.H. & Martin, P.S. (1982), “Neotropical Anachronisms: The Fruits the Gomphotheres Ate”, Science 215: 19–27 — the foundational megafauna-dispersal paper that includes honey locust.
  • Barlow, C. — The Ghosts of Evolution (Basic Books, 2000), chapter on honey locust.
  • Society of Municipal Arborists — Honey-locust street-tree fact sheet and recommended-cultivar list.
  • Wikipedia — Honey locust: en.wikipedia.org/wiki/Honey_locust (CC BY-SA 4.0).

Companion Planting

[ guild · polyculture · cross-layer pairings ]

In a Cross Timbers oak-hickory savanna, honey locust pairs naturally with: chickasaw plum (Prunus angustifolia), maypop / passionflower (Passiflora incarnata), aromatic aster (Symphyotrichum oblongifolium), cosmos (Cosmos bipinnatus), american persimmon (Diospyros virginiana), and fragrant sumac (Rhus aromatica).

honey locust works best as a canopy or sub-canopy partner above the herbaceous and shrub layers.