Photo credit: Forest and Kim Starr, https://flic.kr/p/DaGq1z
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Species at a Glance
Beach vitex is a fast-growing, perennial, woody shrub of coastal sand dunes that can reach heights of 0.5-1 m (1.6-3.3 ft). It has a strong impact on the native flora and fauna along the Carolina coasts, including shading out native plants and disrupting nesting sites for sea turtles. Active community involvement, strategic mapping, and eradication efforts are currently underway to limit the impact this species has on U.S. coastlines.
Leaves: Oval-shaped leaves are oppositely arranged, simple, semi-waxy, smooth, and pale green on the upper side while greyish-white on the underside. Both sides of the leaves are covered in dense fine hairs. Size is typically 5 cm (2 in) long and foliage has a spicy fragrance when crushed.
Flowers: Blue to purple flowers are fragrant, 2.5 cm (1 in) across, and are in short inflorescences out of the leaf axils. Flowering occurs in the summer.
Fruits/Seeds: Round, 0.6 cm (.25 in) wide fruits are purplish-black when ripe.
Stems/Roots: Woody stems have square branchlets with fine wooly hairs. The stems grow horizontally along the ground, often rooting at the nodes and forming mats that can grow over 18 m (60 ft) long.
Beach vitex has several native look-a-likes including silver leaf croton (Croton punctatus), sea beach amaranth (Amaranthus pumilus), and seashore elder (Iva imbricata). Silver leaf croton has unpaired leaves with brown dots on the undersides of the leaves that can be seen with magnification. Sea beach amaranth has red stems and leaves that are crinkled. Seashore elder has long linear leaves and doesn’t have the round fruits found on beach vitex.
An obligate sand-dune species, beach vitex can be found at low elevations on beaches, sand dunes, and rocky shorelines. It is highly drought and salt tolerant and grows best in full sun and sandy or well-drained soils. This plant can currently survive in five U.S. hardiness zones, which increases the likelihood that it will expand its range in the United States.
Beach vitex is a prolific seed producer, but can also reproduce from stem fragments. Seeds and broken off stems can float on water currents and be carried to other beaches. Birds can also facilitate spread as they eat seeds and distribute them in new areas. Seeds and cuttings that are chipped up and spread as mulch may have also helped this species to spread.
Native to Japan and Korea, Beach vitex was introduced to the southeastern United States in in the mid-1980s as an ornamental landscape plant and for sand dune stabilization. Along the coasts of North and South Carolina, beach vitex escaped cultivation and has taken over oceanfront dunes. This species can also be found in Hawaii, Alabama, and Florida.
Note: Distribution data for this species may have changed since the publication of the Mid-Atlantic Field Guide to Aquatic Invasive Species (2016), the source of information for this description.
This rapidly growing and sprawling shrub crowds out native dune plants and allows little light to reach the soil surface. Because of the structure of its root system, beach vitex does not make an ideal dune stabilizer, causing higher rates of erosion. It also threatens the endangered loggerhead sea turtle’s nesting habitat, as well as habitat for rare and threatened plants.
Information for this species profile comes from the Mid-Atlantic Field Guide to Aquatic Invasive Species (2016).