Sunburst Honey Locust Trees

Good Pick for a Street Tree

Image of Sunburst honey locust with its golden leaves.
Sunburst honey locust has golden leaves. David Beaulieu

Taxonomy and Botany of Sunburst Honey Locust Trees

Plant taxonomy categorizes Sunburst honey locust as Gleditsia triacanthos var. inermis 'Suncole.' Note that, although the cultivar name is Suncole, the plant is usually referred to by its trademark name, Sunburst.

Sunburst honey locust is a deciduous tree.

Characteristics of Sunburst Honey Locust Trees

This tree attains a mature height of 30-40 feet, with a spread a bit less than that.

It is 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 more pedestrian light green shade in summer. When it is 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 maples, this tree offers good foliage color for at least two different seasons of the year.

In shape, the compound leaves are fern-like, with a fine texture. The branching pattern is relatively open and airy. They are fast-growing trees.

This tough specimen is tolerant of various harsh environmental phenomena that make life difficult for more delicate plants, as I describe below. Just as importantly, this is a non-messy tree, so it will not make your life more difficult, either (see below under "Thornless, Podless, Non-Messy Honey Locusts").

Planting Zones, Sunlight Requirements, Landscaping and Other Uses

Thornless honey locusts (Gleditsia triacanthos var. inermis) are indigenous to North America. Sunburst can be grown in planting zones 4-9. Plant it in full sun.

These trees can function as specimen plants and/or as street trees (see below).

As with kiwi vines, they allow us to speak, uncharacteristically, 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 do not make especially effective shade trees if you are seeking deep shade. But this same quality makes them good lawn trees. Why? 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 is not surprising that many towns in the United States have a "Locust Street."

Thornless, Podless, Non-Messy Honey Locusts: Shademaster and Sunburst

First of all, note that there are various kinds of locust trees.

For example, black locusts are classified as Robinia pseudoacacia. But even within the Gleditsia genus, we have:

  1. Gleditsia triacanthos, thorny locusts
  2. Gleditsia triacanthos var. inermis, thornless locusts

#1 above is practically defined by the presence of dangerous thorns, thus the common name. Likewise, with #2, 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 (see below). To avoid exposing people's tender skin to accidental piercings from sharp thorns, only #2 is promoted for landscaping use.

While this solves one landscaping problem (namely, safety), it does not solve another associated with Gleditsia, whether thorny or thornless: namely, 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. I say "relatively" because, as Gilman and Watson, for example, point out, on older trees, "some seeds do develop."

Sunburst is not 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 a non-messy tree, 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 are 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 is 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. We have such a tree at the edge our property. 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 I have found for them is 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, and by diseases such as leaf spot and canker disease. Happily, though, honey locusts are deer-resistant plants.

Here are some more of the plant's good qualities. Sunburst honey locusts are:

It is 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. These are very attractive specimens in spring -- attractive to the point of turning heads (well, heads on the necks of plant lovers, anyway).

The bright color of the springtime leaves makes them a true standout in the landscape.

Origins of the Names

Did you ever 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" (or "honeylocust" -- one word) refers to "a sweet gummy substance" found in the seed pods. Meanwhile, the genus name, Gleditsia, is based on a man's last name (Gleditsch, a director of the Berlin Botanical Garden in the 18th century).

But I am much more fascinated by the remainder of the scientific name, Gleditsia triacanthos var. inermis. That is because it is 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 (namely, thorny locust), as MBOT points out. So far, so good. But here is where the contradiction comes in: to indicate the thornless variety, the term inermis is 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. That is, they essentially cancel each other out.

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