Cayratia japonica (Thunb. ex Murray) Gagnep.
(bushkiller, sorrel vine)
Cayratia japonica is a perennial vine in the grape family (Vitaceae), and is native to a wide area of temperate and southeast Asia. It is occasionally cultivated as an ornamental in North America. C. japonica reproduces rapidly and prolifically, and can readily climb into trees and shrubs where it may block sunlight and even break the supporting trees with their weight. In North America, small populations of C. japonica have been reported from Texas and Louisiana (USDA NRCS, 1999), and represent a potential threat to native communities along the Gulf Coast (Duncan, 2001).
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Cayratia japonica (Vitaceae - grape family) is a vine with glabrous, 5-foliate leaves, which are generally 3 to 8 cm long and 1.5 to 4 cm broad. The leaflets are ovate to orbicular-ovate in shape, and bifid tendrils arise opposite from each leaf along the stem. The inflorescences are 6 to 10 cm long corymbs or umbels, and the flowers are small and salmon-colored, with a distinctive cup-shaped disc. The sepals are obscure, the petals are ovate, and there are 4 anthers. The fruits are rounded 2 to 4-seeded berries, and seeds are triangular in shape (Editorial Committee, 1993).Scientific and Common Names:
Synonyms of C. japonica include: Causonis japonica (Thunb. ex Murray) Raf., Cissus japonica (Thunb. ex Murray) Willd., Cissus tenuifolia F. Heyne ex Planch., Columella japonica (Thunb. ex Murray) Merr., Vitis japonica Thunb. ex Murray, Vitis leucocarpa Hayata, and Vitis tenuifolia (F. Heyne ex Planch.) Laws in Hook.f. (TROPICOS, 2001). The common name "bushkiller" signifies its ability to kill other plants by blocking out sunlight and weighing them down.
The overall consequences of this new invader are unknown. Immediate impacts include the ability of C. japonica to kill the plant it grows upon, by stressing it with its weight, blocking out sunlight (Brown, 1992), or competing for other resources. It is not known if C. japonica can act as a ladder fuel.
C. japonica is native to temperate-subtropical Asia. It has been reported from Japan, southern China, Indo-China, the Philippines, Taiwan, New Guinea, and Queensland (Shinners, 1964; Hsu & Kuoh, 1999; TROPICOS, 2001; Thomas, 2002).
Range As An Invader:
In North America, C. japonica is currently reported from only Louisiana and Texas (USDA NRCS, 1999). It generally occurs in damp, deciduous river bottoms (Shinners, 1964), but has also been reported from developed and cultivated areas, such as the Mercer Arboretum in Houston, Texas, and possibly the New Orleans Botanical Garden in Louisiana (Duncan, 2001). There are no reports of C. japonica invading outside of North America.
Reproduction and Methods of Dispersal:
In its native range, C. japonica reproduces both by seed and vegetatively. In North America, however, it appears that C. japonica reproduces only vegetatively. Brown (1992) reported that the flowers of C. japonica seemed to fall off rather than set fruit in Texas. Pat Duncan (2001) states that C. japonica reproduces rapidly and prolifically, and should be eradicated before it becomes widespread.
C. japonica is very difficult to remove once an infestation has become established. Little information is available on its control. Pat Duncan has tried to control it with herbicides at Mercer Botanic Garden in Texas, but has only been able to reduce cover of the infestation by 30% over three years. Digging, or wrenching it out of the ground may be an option, but since it reproduces vegetatively, caution should be used to remove all stem and root fragments to prevent resprouts.
1)Brown, L.E. 1992. Cayratia japonica (Vitaceae) and Paederia foetida (Rubiaceae) adventive in Texas. Phytologia 72(1): 45-47.
2)Editorial Committee (Eds.). 1993. Flora of Taiwan, Second Edition. Volume Three: Angiosperms-Dicotyledons (Hamamelidaceae - Umbelliferae). Editorial Committee of the Flora of Taiwan, Taipei.
3)Duncan, P. 2001. Missouri Botanical Garden, personal communication.
4)Hsu, T.-W. and C.-S. Kuoh. 1999. Cayratia maritima B.R. Jackes (Vitaceae), a new addition to the flora of Taiwan. Botanical Bulletin of Academia Sinica 40: 329-332.
5)Shinners, L.H. 1964. Cayratia japonica (Vitaceae) in southeastern Louisiana: new to the United States. Sida 1: 384.
7)Thomas, M. 2002. Personal communication, Queensland Herbarium (http://www.env.qld.gov.au/herbarium).
8)TROPICOS. 2001. Missouri Botanical Garden's W3TROPICOS database (http://mobot.mobot.org/W3T/Search/vast.html). Missouri Botanical Garden, St. Louis, MO.
9)USDA NRCS. 1999. The PLANTS database (http://plants.usda.gov/plants). National Plant Data Center, Baton Rouge, LA 70874-4490 USA
--Mandy Tu/Wildland Invasive Species Team; March 2001