Species Description
Vitex rotundifolia is a branched deciduous shrub (Westbrooks and Brabson, 2007) that can reach heights between 0.5-1 metres and have horizontal growth up to 20m long, but more commonly has a width around 5 metres (GRI, 2006). According to Westbrooks and Brabson (2007), the \"branchlets are obscurely tetrangular, tomentose, stems procumbent, often rooting at the nodes, forming mats several metres in diameter, 1-3dm long\". The leaves are simple obovate to suborbicular, 2-6.5cm long, 1-4.5cm wide, and an acute base. The upper surface of the leaf is pale green and densely puberulent with a greyish-white lower surface. The lower surface of the leaf is also densely tomentose, short petiolate, and apex rounded (Westbrooks and Brabson, 2007). The foliage has a spicy fragrance when crushed (HNPPD, 2001). The flowers are arranged in terminal clusters in panicles, and about 2cm long (Gresham & Neal, undated; HNPPD, 2001). The corolla is bluish-purple, densely puberulent externally, with the tube about 8mm long. The upper two lobes are 3.5mm long with the margins recurved. The lateral lobe is about 4mm long and the lower lobe is about 7mm long. The base of the lower lobe is marked by two white pilose. The stamen is esxerted from the corolla. The filaments are 9-10mm long and pilose at base. The style is also exserted from the corolla and is about 12mm long. The fruit consists of a dry, globose drupe, and is about 6mm in diameter. During September-October the fruit turns from green into yellow and red-tinged. At maturity the fruit is bluish-black (Westbrooks and Brabson, 2007).
Notes
Vitex rotundifolia was introduced to the southeastern United States from Korea by North Carolina State University Arboretum in the mid-1980s. It was introduced for the purpose of dune stabilisation and for ornamental use. The fruit of V. rotundifolia contains compounds that inhibit lung and colon cancer cells (Westbrooks and Brabson, 2007). According to Westbrooks and Brabson (2007), \"beach vitex meets the definition of a quarantine significant pest because it occupies a very small portion of its potential ecological range in mainland United States, and because it poses a serious threat to certain natural and biological resources (the stability of ocean front dunes and the plant and animal communities that occupy them), as well as the value of beachfront property. The pest risk potential of beach vitex listed as medium-high. Since the plant was intentionally introduced the likelihood of introduction is high. Consequences of introduction are medium due to low economic impact and serious environmental impacts (Westbrooks and Brabson, 2007).
Lifecycle Stages
Beach vitex flowers in May in the Carolinas (Gresham, undated), but can produce flowers throughout the year in Hawaii (HNPPD, 2001). The fruits ripen and dry in the summer while the leaves begin to dry and fall off in autumn, leaving a mat of tangled stems throughout the winter(Gresham, undated). The fruits are persistent on the plant in clusters (Gresham, undated). Seed germination takes up to 3-6 months (HNPPD, 2001).
Uses
Vitex was historically used to suppress sexual desire in women and for similar reasons became a culinary spice in monasteries, hence the common name Monk's pepper (SCNPS, undated). Some of the active chemical compounds in the plant have been linked to female hormone balance, female reproductive organs, menopause, actions on the pituitary gland, and treatment for acne (SCNPS, undated). Compounds in the plant have also been linked to inhibit lung and colon cancers (Gresham & Neal, undated). The plant was originally introduced as an erosion control and ornamental in the United States, however its negative effects on coastal species communities does not favour it for this use (SCNPS, undated). In its native range this plant makes an excellent ground cover, ornamental, and sand dune restoration plant (HNPPD, 2001). In Hawaii the flowers and seeds of the plant are used in the making of leis (HNPDD, 2001). In Japan V. rotundifolia is used as a cold and headache remedy. In Korea the fruit has also been used for the relief of headches caused by upper respiratory infection. Also in Korea it has been used for the rehabilitation and landscaping in seaboard areas (Westbrooks and Brabson, 2007).
Habitat Description
Vitex rotundifolia is an obligate sand dune species (Kim, 2005). It is found at low elevations on beaches, sand dunes, and rocky shorelines (HNPPD, 2001). Beach vitex is highly salt and drought-tolerant (GRI, 2006) and grows best in full sun and sandy or well-drained soils (SCNPS, undated). . According to Madsen,et al, (2005), the plant can survive in five U.S. hardiness zones, which increases the likelihood that this plant may spread to a much wider climatic and geographical range in the United States than it currently occupies.
Reproduction
Vitex rotundifolia reproduces by seed and vegetatively. The plant is a prolific seed producer with estimated seed crops of 22,000 seed/square metres, with field tests resulting in 30% germination (Gresham & Neal, undated). Beach vitex can spread vegetatively through rooting at leaf nodes along runners that can reach lengths of up to 20 metres (GRI, 2006). The seed can be spread by birds eating the fruits while both the seed and stem fragments are dispersed by waves and high tides (GRI, 2006, FWS, undated).
Pathway
Beach vitex was mainly introduced into the United States for dune stabilization and coastal erosion control (Madsen,et al, 2005).Vitex rotundifolia was introduced into the United States partly as an ornamental plant (Madsen,et al, 2005) and is still being sold in nurseries in Texas, Virginia, and Alabama (SCNPS, undated).
Principal source: Gresham, C.A., & Neal, A., undated, An Evaluation of the Invasive Potential of Beach Vitex (Vitex rotundifolia)
Madsen, J.D., Abbott, C., Brown, R., Bruce, L., Byrd, Jr., J., Dibble, E., Ervin, G., Fowler, J., Maddox, V., & Shaw, D., Dec. 2005, Research to Support Integrated Management Systems of Aquatic and Terrestrial Invasive Species, Annual Report Mississippi State University GeoResources Institute in collaboration with United States Geological Survey
Sea Grant North Carolina, 2006, Beach Vitex: Kudzu of the Coast?, Coastwatch Spring 2006, National Sea Grant College Program.
Compiler: National Biological Information Infrastructure (NBII) & IUCN/SSC Invasive Species Specialist Group (ISSG)
Review: Expert review underway: Dr. Randy G. Westbrooks
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USGS BRD
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Whiteville, North Carolina
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USA
Publication date: 2007-05-14
Recommended citation: Global Invasive Species Database (2024) Species profile: Vitex rotundifolia. Downloaded from http://iucngisd.org/gisd/speciesname/Vitex+rotundifolia on 01-09-2024.