While honey locust trees have been admired for centuries, the types that come naturally with thorns and pods can cause problems for homeowners. Happily, podless and thornless honey locusts now exist, thanks to the magic of cultivars.
Taxonomy and Botany of Sunburst Honey Locust Trees
Plant taxonomy categorizes Sunburst honey locust as Gleditsia triacanthos var. inermis Suncole. Although the cultivar name is Suncole, the plant is usually referred to by its trademark name, Sunburst.
Facts About Sunburst Honey Locust Trees
This tree attains a mature height of 30 to 40 feet, with a spread a bit less than that. It's slow to leaf out in spring, but, when it does, its foliar display is a sight to behold. The new foliage starts out yellow, then morphs to a still attractive greenish-yellow, before assuming a plainer light green shade in summer. When it's time for the fall-foliage display, the leaves return more or less to the yellow color that marked them in spring. So, like Bloodgood Japanese maple, it offers colorful foliage for at least two different seasons.
This tough specimen is tolerant of various harsh environmental phenomena that make life difficult for more delicate plants.
Just as importantly, being thornless and podless, this is a non-messy tree, so it won't make your life more difficult, either.
Planting Zones, Growing Needs, Landscaping and Other Uses
These trees can function as specimen plants and/or as street trees. As with kiwi vines, they allow us to speak of a "spring-foliage season" (as opposed to the better-known fall-foliage season), since the color of their leaves is perhaps at its most eye-opening in spring.
Because their canopy is relatively loose and airy, they don't make especially effective shade trees if you're seeking deep shade. But this same quality makes them good lawn trees. This is because the problem with most large trees is that their canopies cast too much shade on the grass trying to grow beneath them (unless you grow a shade-tolerant grass). Grass grown under the relatively open canopy of honey locust trees has a better chance of receiving adequate sunlight.
But honey locusts served many practical functions long before types such as Sunburst were developed and they became popular landscaping trees. The species plant was used traditionally in the making of, for example, railroad ties and fence posts. Given that such products made from its strong, durable wood became fixtures in everyday life, it's not surprising that many towns in the U.S. have a "Locust Street."
Thornless, Podless, Non-Messy Honey Locusts: Shademaster and Sunburst
There are various kinds of locust trees.
For example, black locusts are classified as Robinia pseudoacacia. But even within the Gleditsia genus, we have:
- Gleditsia triacanthos, thorny locusts
- Gleditsia triacanthos var. inermis, thornless locusts
G. triacanthos is practically defined by the presence of dangerous thorns, thus the common name. Likewise, with the inermis variety, people were so impressed that these trees lacked such imposing spines that they took to calling them simply "thornless locusts," a fact reflected even in the Latin name. To avoid exposing people's tender skin to accidental piercings from sharp thorns, only inermis is promoted for landscaping use.
While this solves one landscaping problem (safety), it doesn't solve another associated with Gleditsia, whether thorny or thornless: the mess created when the seed pods drop to earth in fall.
Thus all the hoopla over the development of types of thornless honey locusts that are relatively podless, as well ("relatively" because, as Gilman and Watson point out, on older trees, "some seeds do develop").
Sunburst isn't the only podless type. Shademaster is another example. Whereas Sunburst starts out with yellow leaves, Shademaster's color evolution conforms more to the norm, beginning in spring with green and ending with a golden-yellow fall foliage.
The development of podless types was a major coup and elevated thornless honey locusts to an elite status as non-messy trees, ideal for low-maintenance landscaping. For, in terms of the mess created by fallen leaves, they were already less messy than most. The small size of their leaves means that, when they fall, they're less likely to smother lawn grass, the way larger leaves do (which is one of the reasons why we rake leaves).
But now, with the availability of Sunburst, Shademaster, etc., you have the option of planting a specimen that's about as non-messy as a tree can possibly be. This is a relief, as the types with seed pods can be something of a cleanup nightmare. When the seed pods rain down on us in fall, the grass beneath is blanketed with what look like flat, brown snakes. About the only use for them is in crafts, such as in creating natural kissing balls.
Problems (Pests, Diseases), Outstanding Features of Sunburst Honey Locust Trees
These trees are frequently attacked by insects such as webworm and borers, but gypsy moths tend to leave them alone. They're also attacked by diseases such as leaf spot and canker disease. Happily, honey locusts are deer-resistant plants.
Here are some more of the plant's good qualities. Sunburst honey locusts are:
- Drought-tolerant trees
- Tolerant of compacted soil
- Tolerant of alkalinity in the soil
It's all this "tolerance" that makes them such good street trees.
But their usefulness as street trees only begins to tell the story of their value.
They're very attractive specimens in spring, attractive to the point of turning heads. The bright color of the springtime leaves makes them a true standout in the landscape.
Origins of the Names
You may wonder what these trees could possibly have to do with the grasshopper-like insect called the "locust." As it turns out, the tree was named after the insect because its seed pods were thought to resemble them.
The Missouri Botanical Garden (MBOT) does a good job of explaining this plant's common and scientific names. The common name, "honey locust," refers to "a sweet gummy substance" found in the seed pods. Meanwhile, the genus name, Gleditsia, is based on the last name (Gleditsch) of an 18th-century botanist.
But the remainder of the scientific name, Gleditsia triacanthos var. inermis, is much more fascinating. That is because it's somewhat contradictory.
The Greek acantha, "thorn," preceded by the prefix, tri, "three," gives us triacanthos, a reference to the three-branched thorns of the species plant (thorny locust), as MBOT points out. So far, so good. But here is where the contradiction comes in: To indicate the thornless variety, inermis is the term used. This word comes from the Latin and means "unarmed," as in not armed with thorns or spines. So triacanthos and inermis present us with a juxtaposition of "thorny" and "thornless," respectively. They essentially cancel each other out.