Beach vitex is an invasive plant originally brought from the South Pacific to the South Carolina coast to protect sand dunes from erosion. However, it was quickly realized that its root structure does not anchor the sand nearly as well as native vegetation such as sea oats.
What it does do is outcompete native vegetation, rapidly dominating the coastal and dune-based landscapes and making nesting difficult for both shorebirds and sea turtles. It has recently started to take hold on St. George Island on both the gulf and bay sides.
Vitex grows at such a rapid pace, it has led many to start referring to it as “the kudzu of the coast.” Since beach vitex is introduced to the area, it has very few natural predators to wean it back. It can also live where many native plants cannot and can be seen coming up through the rip rap of a hardened shoreline.
Left alone, beach vitex can become an impenetrable mat of crisscrossing stems which prohibit shorebirds from finding adequate nesting ground. Sea turtles can make a nest on a section of beach that is undisturbed, but by the time the hatchlings start to emerge, the vitex could have covered the nest, making an already incredibly difficult journey even harder.
Vitex is easily identified by its woody stems, or runners, which travel out from the center of the plant in straight lines, as well as by its distinct blue/purple flowers which bloom in late summer and early fall. Vitex’s root system uses a deep tap root at the center of the plant and small, fibrous offshoots along the runners. Neither one of these systems is particularly good at armoring beach dunes, but do allow the plant to be able to regrow from a trimming or from a root system left in the ground after the aboveground portion of the plant is removed.
The seeds and leaves of the beach vitex plant are covered in a waxy coating, enabling the plant to survive inundation by salt water that many other plants do not have the tolerance to live through. In addition, in periods of high water, vitex seed pods are easily separated from the plant where they can float on the surface for up to two weeks while remaining viable.
Researchers are currently doing surveys on how the storm surge brought by Hurricane Michael played a role in the plant’s proliferation on St. George Island. This and other dispersion methods, such as animals eating the fruiting seed pods, may have enabled the plant to spread rapidly to previously unaffected areas.
If you notice beach vitex on your property, experts recommend a careful collection and removal of the seed pods by double bagging them and throwing them into a garbage receptacle. The runners should be cut back to the center tap root, bagged, and thrown away. If the taproot can be accessed, as much of it should be removed as possible.
After that, it is advised to spot treat the area with an herbicide such as imazapyr to prevent regrowth. Replanting native species can also help to muscle out any of the vitex’s remaining stragglers.
Beach vitex in other areas can be reported using EDDMaps (www.eddmaps.org), a system developed by the University of Georgia which uses both a website and a phone app to crowdsource data of sites where invasives have been found. This information can alert area ecologists about the location and severity of various invasive species.
By working to eradicate the vitex now before it grows out of control, we can save time, energy, and resources which could be better used in other areas. In many cases invasives are out of control in the area before they are recognized, but in this situation, we might be able to head it off before it gets too much of a toehold.
Josh Eaton is the coastal training program specialist at the Apalachicola National Estuarine Research Reserve.