Beach Vitex

Vitex rotundifolia

Danielle Devonport

Introduction

Vitex rotundifolia, commonly known as beach vitex, is a deciduous, woody-vine that is considered an invasive species in coastal habitats in the southeastern United States. According to Cousins, Greshman, Riley, and Whitwell (2009), It was introduced from Asia in the 1980's with the hope that its attractive flowers and foliage, salt tolerance, and low-growing habit would allow it to become a widely planted, aesthetically pleasing landscape plant that would also help maintain dune integrity. However, it began to exhibit its invasive potential only 10 years after it became available in the horticultural trade. This species has a rapid growth rate, and a short generation time, reproduces sexually and asexually, and is readily dispersed by water. Many attempts to eradicate the species utilizing chemical control has proved to be somewhat effective, however, stem fragments can readily form new plants. High drought and salt tolerance make beach vitex a strong competitor.

Vitex rotundifolia (Beach vitex)

Taxonomy

Kingdom - Plantae

Subkingdom - Tracheobionta (vascular plants)

Superdivision - Spermatophyta (seed plants)

Division - Magnoliophyta (flowering plants)

Class - Magnoliopsida (dicotyledons)

Subclass - Asteridae

Order - Lamiales

Family - Lamiaceae and Verbenaceae

Genus - Vitex L.

Species - Vitex rotundifolia L. f.

Niche and Habitat

V. rotundifolia has a widespread native range including temperate coastal areas of Japan, Korea and China to Southeast Asia, the Pacific Islands, Australia, and Hawaii. The introduced distribution includes the Atlantic coastline and barrier islands of southeastern United States from Ocracoke Island, North Carolina to Edisto Beach, South Carolina. Scattered occurrences have also been recorded in Maryland, Virginia, Georgia, Alabama and Florida.

In the southeastern US and and in much of its native range, this species is restricted to a narrow seaside zone of shifting, high energy sand dunes and coastal strands. It prefers sandy soils in coastal areas with high sun and tolerates low fertility soils.

Source: EDDMapS

Evolutionary History

Beach vitex has developed many adaptations throughout the years that may be responsible for its invasiveness. "These traits include vegetative reproduction, rapid lateral growth, large seed production, and secondary metabolite production. The extensive, deep (up to 60 cm) root system and lateral growth capabilities are also important characteristics that allow large, intact plants to survive in the hydrophobic substrates they create." According to this same scholarly article, BV fruits and leaves contain many complex metabolites that assist in its survival in the harsh dune environment, which include an insect repellant and thick layers of cuticular compounds to prevent dehydration (Cousins, Gresham, Riley, and Whitwell, 2009, p. 409).

Environmental Impacts

Beach vitex is an invasive species that was introduced to the southeastern United States in 1985 for erosion control. This species outcompetes native strand and dune species (i,e. sea oats), significantly reduces light levels underneath its canopy, and forms dense mats that affect native species. It also restricts the nesting of endangered sea turtles and piping plovers. Although it was initially introduced to enhance dune stabilization, beach vitex is actually less effective at stabilizing dunes than native dune grasses that have more fibrous roots.

Conservation

In the early 2000's, the Beach Vitex Task Force formed to eradicate beach vitex once and for all. This group comprised of local, state, and federal agencies and organizations and funding was provided through a challenge grant from the National Fish and Wildlife Foundation and the Federal Interagency Committee for the Management of Noxious and Exotic Weeds. Their main objectives included:

Early Detection: Detection and reporting of beach vitex populations
Prevention: Removal of seedlings from public areas to prevent further spread of the plant
Rapid Assessment: An ecological assessment to determine the impact of the invader on native plants and animals; and to determine if the plant should be regulated by state and federal agencies
Rapid Response: Development of environmentally sound methods for removal of large plantings
Restoration: Development of methods for restoration with native plants once beach vitex is removed

Unfortunately, the task force disbanded due to lack of funding and beach vitex continues to take over.

In order to eradicate this species, chemical controls such as Imazapyr and glyphosate are commonly used. Biological and manual control have been proven ineffective. Imazapyr and glyphosate are not only harmful to the surrounding environment, but they also impose serious health effects to humans. Imazapyr is a non-selective herbicide and some formulations can cause severe, irreversible eye damage. Glyphosate is a synthetic herbicide patented by Monsanto. It has been banned in many states and countries due to its classification as a probable carcinogenic to humans by the World Health Organization's International Agency for Research and Cancer (IARC).

Friends or Foes?

This species competes with other native dune plants in the southeast, such as sea oats, American beachgrass, and seaside panicum. In addition, beach vitex threatens endangered loggerhead sea turtle nesting habitats and habitat for sea beach amaranth, a federally threatened plant.

Coastal Invasive Species - Beach Vitex - FISAW 2020

Beach Vitex: Kudzu of the Coast?

Web Resources for Audience to Explore

EDDMapS

EDDMapS is a wed-based mapping system for documenting invasive species and pest distribution. This site aggregates data from other databases and organizations as well as volunteer observations to create a national network of invasive species and pest distribution data that is shared with educators, land managers, conservation biologists, and beyond.

NC Cooperative Extension: Brunswick County

This website has great information regarding the Carolina's Beach Vitex Task Force.

University of Florida Center for Aquatic and Invasive Plants

University of Florida is a highly reputable source for accurate information regarding aquatic and invasive plants. This website goes into detail about a plant's history, its characteristics, distribution, etc.

North Carolina Extension Gardener Plant Toolbox

The North Carolina Extension Gardener Plant Toolbox contains detailed descriptions and photographs of 4,225 plants that grow in and around North Carolina. This site is based on evaluation of plant databases around the world, surveys of Extension agents, Extension Master Gardener volunteers (EMGVs) and plant database users, and focus groups.

iNaturalist

iNaturalist is an incredibly useful application that relies on citizen scientists to record and share observations to collect data on a specific species. It is used worldwide and an excellent source for plant identification in the field.

USDA National Invasive Species Information Center

This site serves as a reference and educational gateway to information, organizations, and services about invasive species.

Resources

US Dept of Agriculture: National Invasive Species Information Center - https://www.invasivespeciesinfo.gov/profile/beach-vitex

Clemson University: Home and Garden Information Center - https://hgic.clemson.edu/factsheet/identifying-managing-beach-vitex/

University of Florida: Center for Aquatic and Invasive Plants - http://plants.ifas.ufl.edu/vitex-rotundifolia/

Beach Dune Sand Hydrophobicity Due to the Presence of Beach Vitex (Vitex rotundifolia L. f.) - Matthew M. Cousins, Charles A. Gresham, Melissa B. Riley, Ted Whitwell - https://pubs-acs-org.liblink.uncw.edu/doi/10.1021/jf8025259

USRTK - https://usrtk.org/pesticides/glyphosate-health-concerns/

US Fish and Wildlife - https://www.fws.gov/raleigh/pdfs/beach_vitex.pdf

CABI: Invasive Species Compendium - https://www.cabi.org/isc/datasheet/56553

NCSU Extension Gardener Plant Toolbox - https://plants.ces.ncsu.edu/plants/vitex-trifolia-subsp-litoralis/

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