Celastrus orbiculatus Thunb., Celastraceae

Click on an image for links to BIGGER PICTURES

Present on Pacific Islands?  no

Primarily a threat at high elevations?  no

Risk assessment results:  High risk; score: 13.5 (Hawaii-Pacific Weed Risk Assessment for Celastrus orbiculatus)

Other Latin names:  Celastrus articulatus Thunb.; Celastrus orbiculata Thunb.

Common name(s): [more details]

English: Asian bittersweet, Asiatic bittersweet, Japanese bittersweet, Oriental bittersweet, climbing spindle berry, climbing spindleberry, oriental bittersweet, round-leaved bittersweet

Habit:  vine

Description:  "Celastrus orbiculatus is a deciduous woody vine which climbs by means of twining about a support. The branches are round, glabrous, light to darker brown, usually with noticeable lenticels. The outer surface of its roots are characteristically bright orange. Individuals have been found climbing to heights up to 18 m in the Great Smoky mountains (Langdon 1993). Plants with stems 5 cm diameter at breast height are common and some reach 13 cm dbh. Axillary buds are 1-3 mm long, rounded, with outer scales sometimes becoming spine-like. Leaves are glabrous, alternate in arrangement and extremely variable in size and shape, from broadly oblong-obovate to suborbicular, 2 -12 cm long and 1.5 to 8 cm wide. Leaf margins are crenate-serrate and leaf base cuneate to obtuse, tip acute to rounded. Petioles are 1-3 cm long. Inflorescences are axillary cymes, usually containing 3 - 7 flowers. However inflorescences are sometimes terminal in male plants. Flowers are small, greenish-yellow, and usually become unisexual by abortion or reduction of male or female parts, thus the plants are usually dioecious (Brizicky 1964). Occasional vines develop both unisexual and perfect flowers and are then termed polygamo-dioecious (Gleason and Cronquist 1991). Another reported variation is occasional monoecious plants, i.e. with both male and female flowers on the same vine (Hou 1955). The flowers have 5 sepals and 5 petals. Male flowers contain 5 stamens which are about as long as the petals and inserted at the edge of a cup-shaped disk around a vestigial pistil. Female flowers have vestigial stamens, a 3-lobed stigma, columnar style and well a developed superior ovary, sometimes embedded in the disk (Gleason and Cronquist 1991). The fruit are globose, loculicidal capsules, 6 to 8 mm in diameter, which change in color from green to bright yellow as they mature. The capsules are three valved with each valve (locule) containing one or two brown seeds completely enclosed in a fleshy red aril. Upon ripening, the yellow outer covering splits open to reveal the red aril, thus presenting a brightly bicolored 'dispersal flag'." "The primary taxonomic reference for this section is Hou (1955). " (TNC Element Stewardship Abstract)

See also Invasive Plants of the World (Weber, 2003), p. 92; GISD: Celastrum orbiculatus, "Species Description" under "General" tab.

Habitat/ecology:  In southeastern USA, "[o]ccurs on a wide range of sites mainly along forest edges. Found as scattered plants to extensive infestations in forest openings, margins, and roadsides as well as in meadows. Mostly shade intolerant. Colonizes by prolific vine growth and seedlings, and spreads by bird- and other animal-dispersed seeds and humans collecting decorative fruit-bearing vines." (Nonnative Invasive Plants of Southern Forests, p. 31)

Invaded habitats include riparian habitats, flood plains, forest margins, woodland, and disturbed sites. (Invasive plant species of the world (CABI), p. 99)

"Celastrus orbiculatus habitat on its native continent of Asia is said to be lowland slopes or thickets at altitudes from 100 to 1,400 m. The vine is widely distributed in northern and central Japan and Korea. In China it is found primarily in provinces north of the Yangtze River (Hou 1955). Its North American habitat preferences are wide but seem to be exclusively terrestrial. It is variously described as occupying open woods and thickets (Gleason and Cronquist 1991), roadsides, fence-rows, and thickets (Fernald 1970), alluvial woods, roadsides and thickets (Radford et al. 1968). " (TNC Element Stewardship Abstract)

"In the native range, this vine grows mostly in broadleaved and mixed forests; in China it reaches 2200m altitude. The leaf morphology is highly variatble (FOC, 2014). Seeds are dispersed by birds and mammals. The plant prolifically sprouts from below-ground rhizomes and thus expands vegetatively.

"Oriental bittersweet invades forest ecosystems and has a strong impact on the vegetation. The fast-growing stems smother shrubs and climb into tree canopies, shading out other plant species and accumulating masses of stems. The increased weight makes trees prone to uprooting and breakage, especially during high winds and heavy snowfall (Swearingen, 2006). In heavily infested areas, forests are degraded and lose their value for wildlife. "Ecology. Occurs on a wide range of site mainly along forest edges. Found as scattered plants to extensive infestations in forest opening, margins, an roadsides as well as in meadows. Mostly shade intolerant. Colonizes by prolific vine grown that seedlings, and spreads by bird- and other animal-dispersed seeds and humans collecting decorative fruit-bearing vines."

"Establishment of this vine depends on disturbance but, once established the vine can invade closed forests (Silveri et al.<, 2001; Lett et al., 2001). Seedlings tolerate shade but grow slowly; they respond to gaps by quickly increasing photosynthesis and growth rate (Leicht and Silander, 2006). The plant is able to persist in deep shade, despite slow growth in such conditions. This allows the vine to penetrate into closed forests (Ellsworth et al., 2004). Dense infestations of Celastrus orbiculatus change soil processes, as nitrogen mineralization and litter decomposition rates were highter in plots with C. orbiculatus compared with uninvaded plots (Leicht-Young et al., 2007).

"In the eastern USA, Oriental bittersweet hybridzes with the native American bittersweet (Celastrus scandens). Since the invasive liana grows faster and is highly competitive, the native congener is displaced (Swearingen, 2006). Both species are similar in their morphology and biology (Leicht-Young et al., 2007)." (Invasive plant species of the world (CABI), p.p 98-99)

"This fast growing vine prolifically sprouts from below-ground rhizomes. It grows along the floor, into the canopies, and its impacts are blanketing and shading out the native vegetation, killing trees due to strangulation, and inceasing [sic] susceptibility to wind and ice damage of host trees, reducing forest regeneration in invaded areas. Seeds are dispersed by birds and mammals, and germinate even in low light. Seedlings are very shade tolerant; they respond to gaps by quickly increasing photosynthesis and growth rate." (Invasive Plants of the World (Weber, 2003), p. 92)

"Oriental bittersweet dominates gap and edge environments, but may also colonise undisturbed forest (Ellsworth et al. 2004b). Dreyer (2003) states, \'Its North American habitat preferences have been stated as wide. It is variously described as occupying open woods and thickets, roadsides, fence-rows, and thickets, alluvial woods, roadsides and thickets\'." (GISD: Celastrum orbiculatus, "Habitat Description" on the "General" tab)

"McNab and Loftis (2002) recorded in their study that, [sic] \'C. orbiculatus vines emerged from winter dormancy and began stem elongation several weeks before the arborescent overstory. We observed that many C. orbiculatus seedlings from 0.2 to 0.5m height had experienced periodic dieback of the stem terminal followed by resprouting. Paterson (1975) reported that tip ends of C. orbiculatus stems are typically killed by onset of freezing temperatures in the fall and although not reported, susceptibility of seedlings to cold damage could be influenced by their location in relation to canopy gaps.\" Silveri et al. (2001) state that, [sic] \'In the absence of disturbance, C. orbiculatus invades forested habitat using a strategy similar to the 'advance regeneration' of some canopy trees. Like these shade tolerant species (Philips and Shure 1990; White 1991), C. orbiculatus seedlings may persist for long periods on the forest floor but require creation of a gap to reach the canopy and reproduce sexually.\'" (GISD: Celastrum orbiculatus, "Lifecycle Stages" on the "General" tab)

Propagation:  "Colonizes by prolific vine growth and seedlings, and spreads by bird- and other animal-dispersed seeds and humans collecting decorative fruit-bearing vines." (Nonnative Invasive Plants of Southern Forests, p. 31)

"Flowers bloom in late May to early June in Connecticut. Fruit ripens in September and remains on the vine through much of the winter. Brizicky (1964) notes that hymenopterous insects, especially bees, are its main pollinators, but Wyman (1950) also found wind pollination to be effective. Wyman also states C. orbiculatus and C. scandens can pollinate each other, and White and Bowden (1947) created a fertile hybrid through a controlled breeding program. No naturally occurring hybrid plants have been reported in the literature. However, Dreyer et al, (1987) reported two distinct sizes of pollen grains on certain individuals, tentatively identified as C. orbiculatus, growing in close proximity to C. scandens. They speculated that these plants may be hybrids. ¶Fruit dispersal is generally thought to be by birds and small mammals. In an unpublished undergraduate study in Connecticut, removal of fruit from seven species of woody plants by birds was observed during fall and winter (Wheeler 1987). C. orbiculatus was considered an important winter food, and was comparable in lipid and sugar content to the fruit of other species, but was not taken at all by animals in the fall. Black-capped Chickadees, Northern Mockingbirds, European Starlings and Blue Jays all fed on C. orbiculatus during the winter months. ¶"Humans are also important dispersal agents. Fruiting stems are collected for dried flower arrangements, and are soon disposed of on compost and brush piles. The vine is highly attractive, easy to grow and propagate, and available at many nurseries, where it is often mislabeled as C. scandens. It was, and still may be, planted extensively in highway landscaping and for 'conservation' plantings for wildlife food and cover, and erosion control, both as itself or mistakenly for C. scandens. ¶Seed germination is generally high in C. orbiculatus, particularly when compared to C. scandens. Patterson (1974) conducted a wide variety of germination tests with seed from 4 eastern US states and found between 30 and 95% germination. He also noted that the highest germination rates occurred at low light intensities. Dreyer et al. (1987) confirmed the ability to germinate at low light levels and reported germination from 59 to 82%. Also in Connecticut, Clement et al. (1991) found C. orbiculatus produced 4.2 viable seed per fruit compared to 3.2 in C. scandens. Mean germination rates for C. orbiculatus were 70% compared to 20 % for C. scandens. In field experiments Clement et al (1991) found that C. orbiculatus photosynthetic rates increased with increasing light intensity. In contrast, C. scandens photosynthetic rates at the same sites, tended to reach a plateau beyond which additional light had no significant effect. The ability of C. orbiculatus to acclimate to a variety of irradiance levels may be one of the factors which has allowed it to spread rapidly. ¶C. orbiculatus rootsuckers prolifically, especially after the main vine is damaged or cut. Rootsuckering is a common occurrence and results in large clones or patches which often spread from one or a few original plants which originated as seedlings. Patterson (1974) noted the scarcity of other plants under dense canopies of C. orbiculatus, but could not attribute this to soil moisture, soil nutrients, precipitation interception or temperature changes. However, shading by the C. orbiculatus canopy was considered a potentially significant factor." (TNC Element Stewardship Abstract)

"This fast growing vine prolifically sprouts from below-ground rhizomes. .&nbnsp;. . Seeds are dispersed by birds and mammals, and germinate even in low light. Seedlings are very shade tolerant; they respond to gaps by quickly increasing photosynthesis and growth rate." (Invasive Plants of the World (Weber, 2003), p. 92)

"McNab and Loftis (2002) state that, \"Seeds are believed to be disseminated primarily by birds (Stoll et al. 1980 and Dreyer, 1994) that consume the leathery capsule consisting of three to five seeds, which ripens in the fall.\'" (GISD: Celastrum orbiculatus, "Reproduction" under the "General" tab)

Native range:  "Celastrus orbiculatus is native to temperate east Asia, including central and northern Japan, Korea, and China north of the Yangtze River. " (TNC Element Stewardship Abstract)

Celastrus orbiculatus is native to China, Japan, Korea, Mongolia, and the Russian Federation. (GRIN)

China, Japan, DPR Korea, Rep. of Korea, Mongolia, Russian Federation (GISD: Celastrum orbiculatus, "Distribution" tab)

Impacts and invaded habitats:  "Celastrus orbiculatus is a deciduous, dioecious round-leaved vine that makes use of the 'sit and wait' invasion strategy. This species establishes under closed canopy forest conditions and persists indefinitely until it is released by a disturbance that creates conditions optimal for rapid growth. It invades forested land but has also been known to persist on coasts and may possibly disrupt dune formations. C. orbiculatus can overtop and girdle native trees and shrubs along roads, in clearings and in forest gaps. Identifying and eradicating populations before it they are released by an opening in the canopy is the easiest method of control." (GISD: Celastrum orbiculatus, "General"&nbsnp;tab)

Invaded habitats: "Forests, riparian habitats, rocky places." (Invasive Plants of the World (Weber, 2003), p. 92)

"McNab and Loftis (2002) observe that, [sic] C. orbiculatus characteristics of shade tolerance, rapid growth response upon release from shading, prolific and consistent annual seed production with high viability and germination, and, adaptation to a wide range of suitable environments make it highly competitive with native vegetation and potentially difficult to manage in forests that are subject to recurrent natural or managed disturbance. Ellsworth et al. (2004) state, \'Once established, C. orbiculatus can overtop and girdle native trees and shrubs along roads, in clearings and in forest gaps\'. The success of C. orbiculatus may be due to frequent natural and human-caused disturbances in the eastern U.S. (Robertson et al. 1994 ; Luken et al. 1997 ; McDonnell et al. 1997 ; McNab and Loftis, 2002 ). Disturbances can lead to plant invasions through an increase in the availability of resources such as germination sites, light and water (Hobbs and Huenneke, 1992 ; Greenberg et al. 2001 ). However, it has also been suggested that C. orbiculatus seedlings can become established and survive in intact forest understory (Paterson, 1974 , 1975 ; Greenberg et al. 2001 ). This ability has important implications for forest management because disturbances that result in increases in light may release C. orbiculatus already established in the understory. Silveri et al. (2001) state that, [sic] \'The annual growth rate of C. orbiculatus may exceed 3m (Paterson 1974), allowing plants in open-light habitats to climb a canopy-sized tree in 3-4 growing seasons. Twining vines are generally limited to small-diameter supports (Teramura et al. 1991), but C. orbiculatus is able to climb tree trunks with a wide variety of diameters, aided by spiny projections around its bud and leaf scars that lodge in the host's bark. C. orbiculatus kills other vegetation through blanketing and constrictive twining, and halts the succession of young deciduous forests (McNab and Meeker 1987; Dreyer 1994).\' Ellsworth et al. (2004) also suggest that failure to control it would result in severe forest degradation and considerably higher future costs associated with forest restoration." (GISD: Celastrum orbiculatus, "General Impacts" under "General" tab)

Presence:

Pacific
Country/Terr./St. & Island group	Location	Cited status & Cited as invasive & Cited as cultivated & Cited as aboriginal introduction?	Reference & Comments
French Polynesia Society Islands	Maupiti (Maurua) Island		Consortium of Pacific Herbaria (2018)

Pacific Rim
Country/Terr./St. & Island group	Location	Cited status & Cited as invasive & Cited as cultivated & Cited as aboriginal introduction?	Reference & Comments
Central America Central America (Pacific rim)	Panama (Republic of)	introduced	Global Invasive Species Database (year unknown) accessed 20171208
Japan Japan	Japan	introduced	U.S. National Plant Germplasm System (year unknown) naturalized in NZ; species cited as cultivated/ornamental/weed (potential seed contaminant), but not specifically in Japan
New Zealand New Zealand	New Zealand (country)	introduced invasive	Weber, Ewald (2017) (p. 99)
New Zealand New Zealand	New Zealand (country)	introduced invasive	Owen, S.J. (1996) Celastrus orbiculatus is cited as a weed of concern on conservation land in New Zealand.
New Zealand New Zealand	New Zealand (country)	introduced invasive	CAB International (2017)
New Zealand New Zealand	New Zealand (country)	introduced	U.S. National Plant Germplasm System (year unknown) naturalized in NZ; species cited as cultivated/ornamental/weed (potential seed contaminant), but not specifically in NZ
New Zealand New Zealand	New Zealand (country)	introduced	Global Invasive Species Database (year unknown) accessed 20171208
New Zealand New Zealand	North Island (NZ)		Consortium of Pacific Herbaria (2018)

Also reported from
Country/Terr./St. & Island group	Location	Cited status & Cited as invasive & Cited as cultivated & Cited as aboriginal introduction?	Reference & Comments
Canada Canada	Canada	introduced	Weber, Ewald (2017) (p. 99)
Canada Canada	Canada	introduced	Global Invasive Species Database (year unknown) accessed 20171208
Canada Canada	Canada	introduced invasive cultivated	Kaufman, Sylvan Ramsey/Kaufman, Wallace (2007) (p. 207) "Grows from southern Ontario south to Louisiana and Georgia and west to Iowa." (p. 207); "...arrived [into North America] from China as an ornamental vine around 1860." (p.208)
United States (continental except west coast) United States (other states)	United States (other states)	introduced invasive	Weber, Ewald (2017) (p. 99)
United States (continental except west coast) United States (other states)	United States (other states)	introduced	Global Invasive Species Database (year unknown) accessed 20171208
United States (continental except west coast) United States (other states)	United States (other states)	introduced invasive cultivated	Kaufman, Sylvan Ramsey/Kaufman, Wallace (2007) (p. 207) "Grows from southern Ontario south to Louisiana and Georgia and west to Iowa." (p. 207); "...arrived [into North America] from China as an ornamental vine around 1860." (p.208)

Comments:  There is no mention of Celastrus orbiculartus being present in the Pacific (except in the Pacific Rim country of New Zealand) in either Invasive Plants of the World (Weber, 2003) p. 92 or in GRIN.

"[Celastrus orbicularis] is a vigorous vine that prefers sunny spots but is also shade-tolerant. Once established, it can ‘wait’ for a disturbance in forest canopy and then compete with native species for resources." (NZ National Pest Plant Accord 2012)

"This species can be reliably distinguished from...Celastrus scandens only by the location of female flowers and fruit. In C. orbiculatus they are borne in clusters of 3 - 7 in the axils of leaves. Celastrus orbiculatus fruit are never arranged in terminal clusters. In contrast the flowers and fruit of C. scandens are borne in terminal panicles which may contain numerous flowers or fruits. A second, less reliable, difference is the yellow color of the outer fruit covering in C. orbiculatus vs. the orange color of C. scandens outer fruit cover. The color of the inner aril is red in both species. Identification by leaf shape or size, or by male inflorescence type is not reliable. Illustrations showing the differences between the two species can be found in Gleason (1952) and McNab and Meeker (1987)." (TNC Element Stewardship Abstract)

Control:  "Identifying and eradicating populations before it they are released by an opening in the canopy is the easiest method of control." (GISD: Celastrum orbiculatus, "General" tab)

"Recommended control procedures: ■ Thoroughly wet all leaves with one of the following herbicides in water with a surfactant (July to October [southeastern USA]): Garlon 4, Garlon 3A, or a glyphosate herbicide as a 2-percent solution (8 ounces per 3-gallon mix). ■ For stems too tall for foliar sprays, apply Garlon 4 as a 20-percent solution in commercially available basal oil, diesel fuel, or kerosene (2.5 quarts per 3-gallon mix) with a penetrant (check with herbicide distributor) to the lower 16 inches of stems. Or, cut large stems and immediately treat the cut surfaces with one of the following herbicides as a 25-percent solution (32 ounces per 1-gallon mix)." (Nonnative Invasive Plants of Southern Forests, pp. 79-80) (IMPORTANT NOTE: Although every effort has been made to transcribe this information accurately, PIER recommends that you consult the original source document for details before mixing/applying any herbicide. Additionally, PIER stresses that you must comply with local laws regarding herbicide use.)

"Control is difficult because root fragments may produce new plants. Manual control includes regular mowing, cutting and hand-pulling. Triclopyr and glyphosate herbicides applied to cut stems work well; control is best carried out late in the season when the first frosts appear. Foliar sprays with 2,4-D plus triclopyr are also effective. Dense and low patches can be cut entirely to the ground in spring and regrowth sprayed with herbicide (Hutchinson, 1992; Swearingen, 2006)." (Invasive plant species of the world (CABI), p. 99) (IMPORTANT NOTE: Although every effort has been made to transcribe this information accurately, PIER recommends that you consult the original source document for details before mixing/applying any herbicide. Additionally, PIER stresses that you must comply with local laws regarding herbicide use.)

"Control is difficult because root fragments may produce new plants. Manual control includes regular mowing, cutting and hand-pulling. Triclopyr and glyphosate herbicides applied to cut stems work well; control is best carried out late in the season when the first frosts appear. Foliar sprays with 2,4-D plus triclopyr are also effective." (Invasive Plants of the World (Weber, 2003), p. 92) (IMPORTANT NOTE: Although every effort has been made to transcribe this information accurately, PIER recommends that you consult the original source document for details before mixing/applying any herbicide. Additionally, PIER stresses that you must comply with local laws regarding herbicide use.)