Sunburst Honey Locust

Gleditsia triacanthos var. inermis 'Suncole'

There are three Sunburst honey locusts in the Park, one each in the northwest, east, and northeast triangles. See Wikipedia entry here.
The honey locust is a deciduous tree native to central North America with a band stretching across southern Pennsylvania. It is mostly found in the moist soil of river valleys ranging from southeastern South Dakota to New Orleans and central Texas, and as far east as eastern Pennsylvania.
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Sunburst honey locust in northwest triangle
Honey locust factoids:
  • The species name triacanthos derives from the fact that most honey locusts have thorns (acanthos) in groups of three or more (tri) running up the trunk and branches. Thornless varieties like ours are available. There are several heavily-thorned cultivars on the south side of the 1500 block of Spring Garden Street. The variety name inermis is Latin for "unarmed."
  • The term honey in the common name derives from the sweet tasting seed pods. These pea-like pods are eaten by animals and were used as sweeteners in Native American foods.
  • There has been conjecture that the large sweet seedpods of the honey locust were eaten and the seeds spread by now extinct large animals. Shortly after humans arrived in North America, half of the existing megafauna species (animals weighing more than 100 pounds) went extinct, leaving the honey locust seeds with no dispersal mechanism. This may apply to the even juicier seedpods of the Kentucky coffeetrees down in Aviator Park.
  • The Sunburst honey locust is a deciduous tree, with compound leaves (multiple leaves on one stem) that turn bright yellow in autumn.
  • These trees have a fairly open canopy, unlike the maples for example.
  • They are "polygamodioecious" trees. This means that each honeylocust tree has either male or female flowers, but each tree also produces some "perfect" flowers that have both male and female parts. 
    "Podless" honeylocust trees selected and marketed by nurseries are male trees that tend to produce few perfect flowers. Our Sunburst hybrids are both thornless and podless. See page on red maples for more on tree reproduction organs. 
  • The scientific naming conventions for varieties and cultivars are exemplified with our honey locusts. The variety inermis is italicized and the cultivar term Suncole is not, but is capitalized and placed in single quotation marks. To complicate matters, the trademarked term Sunburst is not part of the scientific name but is used in marketing. See outside link here.
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Spreading branches of the sunburst honey locust in east triangle
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Sunburst honey locust in northeast triangle
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Photo of the trunk of the honey locust in the east triangle on April 16
On the right are stalks of male flower buds prior to opening. The seedpods from honey locusts can get messy after they fall, so many cultivars are male and therefore seedless.
The honey locusts are special favorites of the lichen. All three trees in the Park have a nice dispay of lichen.
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Photo on 5/20/2020 showing the cluster of flowers coming right out of the trunk of the honey locust in the eastern triangle. The whole tree takes on a yellow tint with thousands of yellow flowers and young light-green leaves.
If you want to see some large honey locusts with their seed pods, head into the courtyard behind NxNW Towers in early November. The photos below show the pods on the ground and with seeds removed.
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honey locust pods and seeds nxnw 11.5.20
Botany 101
Trees and their seed dispersers exist in symbiotic relationships, just as many flowering plants depend on insects for reproduction. The flower offers nectar to the bees, and the bees spread the pollen of the flowers. Nectar is expensive for the flower, but it is the cost of "having sex." Fruit is another expense for reproduction; the tree makes tasty fruit that is eaten by animals and the seeds are dispersed in the animal droppings.
Sometimes it is difficult to find an existing animal that would be able to swallow large fruits with large seeds, like the avocado. Scientists have theorized that large animals, called megafauna, that existed in the past and dispersed the large intact avocado seeds became extinct. The plant, unless this animal extinction occurs slowly, cannot evolve fast enough to make up for the loss of its disperser and may itself become threatened with extinction. North American mammoths, giant ground sloths, and 400-pound beavers were here prior to 13,000 years ago, but now leave only their fossil remains on this continent. A seed disperser's going extinct threatens the plant that produces the seed with extinction as well.
 
The pulp of the pods of the honey locust can have a 35% sugar content. The seeds have to pass through the guts of animals to germinate. Some think that entire honey locust seed pods were eaten intact by large animals, chewed, swallowed, and the tough seeds passed through the animal's gut into its feces at a distance from the parent tree. When the megafauna in North America was wiped out when humans settled the continent after the last ice age peak 18,000 years ago, many plants, like our honey locusts and the Kentucky coffeetrees in Aviator Park, had their natural range severely restricted. 
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Tough seed pod, green pulp, and large seeds of the Kentucky coffeetrees in Aviator Park in January 2021.