I would never wish upon anyone a plague of locusts. Unless, that is, I’m wishing for you to come across a dense stand of bristly locust (Robinia hispida) shrubs in bloom along a trail or edge of the woods. Then, by all means, may this kind of pox be upon you.
At first glance, the stems of bristly locust look mean and dangerous, covered in what appear to be numerous spines and prickles. But they are actually soft, bristly hairs that give this plant both the common name of bristly locust and the epithet in the botanical name of “hispida.”
In botany, there are specific names for not only every plant part but every type and variation of that part. There are names for all of the different types of leaf shapes, leaf margins or edges, flower shapes and arrangements, and just about any differentiating part or piece of a plant. In fact, there are over 20 terms to describe the varying appearances and forms of hairs that may be found on plants.
While I have no intention of listing and defining all of the various states and conditions of hairiness on plants in this article, some of the most common and general terms for plant hairiness include glabrous-having no hairs, a smooth surface; pubescent-having hairs; hispid-having prickly hairs; downy-long, soft, wooly-like hairs; and hirsute-having coarse hairs.
While these hispid, bristly hairs resembling tiny thorns might push you away at first glance, the large clusters of pink and yellow pea-shaped flowers will attract you to this plant. Locust trees and shrubs are in the pea family (Lamiaceae) and all have typical pea-type flowers. The flowers of the common black locust (Robinia pseudoacacia) are white and otherwise resemble those of the bristly locust.
The bristly locust is a common shrub that grows throughout the southeastern United States from Maryland to South Georgia and Southern Alabama, although some sources claim that its original range was only in Southern Appalachia and was spread outside of that range by people.
There is a close relative of bristly locust that has a much narrower range of growing locations, Robinia hartwigii, or Hartwig’s Locust. This large shrub/small tree grows only to about 12 feet high and is only found on high-elevation granitic dome rock outcroppings in Jackson and Macon counties. A great place to see this species is at the top of Whiteside Mountain between Cashiers and Highlands.
Bristly locust grows much shorter than other locust plants and usually reaches only about 3 feet high. To many, these shrubs appear to be saplings of the much larger black locust which can exceed 60 feet. This unfortunately leads to many people pruning or digging them out, as the black locust is often considered a weedy tree species.
Bristly locust is a beautiful, low-growing shrub that is the host plant for various species of moth including the banded tussock moth, one of those hairy looking caterpillars that may or may not sting you. In this case, you do not want to touch them as their hairs sting and feel similar to ant bits or stinging nettles.
When it comes to the plant look and touch, as the bristly hairs won’t bite you and the flowers look and smell beautiful. They taste pretty good too. There’s something about deep frying flower fritters in the late spring, and the flowers of locust trees and shrubs make for a delicious snack for you and the native bees that love to pollinate it.
(The Joyful Botanist leads weekly wildflower walks most Fridays and offers consultations and private group tours through Bigelow’s Botanical Excursions. bigelownc@gmail.com.)