Clematis terniflora DC., Ranunculaceae

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Present on Pacific Islands?  yes

Primarily a threat at high elevations?  no

Risk assessment results:  High risk; score: 13 (Hawaii-Pacific Weed Risk Assessment for Clematis terniflora)

Other Latin names:  Clematis flammula var. robusta Carrière; Clematis maximowicziana Franch. & Sav.; Clematis paniculata Thunb.

Common name(s): [more details]

English: Japanese virgin's bower, leatherleaf clematis, sweet autumn clematis, sweet autumn virgin's bower, yam-leaf clematis, yam-leaved clematis

Habit:  vine

Description:  "Evergreen to semievergreen perennial vine covered with clouds of fragrant 4-petaled white flowers (1 in. [2.5 cm] diameter) in late summer to fall. Flowers are in branched clusters growing from the leaf axils along the vine's new growth. Leaves are arranged oppositely along the stems and are made up of 3 to 5 leaflets each 2 to 3 in. (5 to 7.6 cm) long. Autumn virgin's bower leaflets are more leathery and rounded as opposed to the jagged teeth on most of the leaf edges of Virgin's bower. Seed heads are also ornamental, looking like silvery-gray rounded puffs of feathery hairs. Autumn virgin's bower climbs to 15 ft. (4.6 m) by twining." (Kaufman & Kaufman 2007, p. 224-225)

Habitat/ecology:  In parts of its non-native range, Clematis terniflora is "[f]ound along streambanks and in thickets and moist woods in New England south to Florida, west to Nebraska and Texas." (Kaufman & Kaufman 2007, p. 225)

In North America, "[o]ften found along forest edges and in forest gaps, also in fencerows, old fields, and in coastal areas. Prefers shun to part shade." (Kaufman & Kaufman 2007, p. 207)

Propagation:  "Clematis terniflora . . . may seed into the landscape." (Seiler et al. 2018)

"Bittersweet [PIER ed.: Clematis terniflora] seedlings can establish in dense shade, then take advantage of gaps created after storems, fire, or human disturbance to climb into the light. The vines grow rapidly.... Seeds may be an important winter food source for birds and are dispersed by birds to new areas. . . . "Cut plants will send up suckers from the roots. . . ." (Kaufman & Kaufman 2007, p. 207-208)

Native range:  The native range of Clematis terniflora includes China, Japan, Korea, Taiwan, Mongolia, and the Russian Federation. (GRIN)

Impacts and invaded habitats:  Clematis terniflora "clambers over the ground and over shrubs and small trees, blocking the light to the plants below it. . . . Botanists started finding it in natural areas [PIER ed.: in the U.S.] in the early 1950s." (Kaufman & Kaufman 2007, p. 225)

"Bittersweet [PIER ed.: Clematis terniflora] seedlings can establish in dense shade, then take advantage of gaps created after storems, fire, or human disturbance to climb into the light. The vines grow rapidly and it is sometimes called "the kudzu of the North" as it overtops trees, cutting off light to the plants below. Seeds may be an important winter food source for birds and are dispersed by birds to new areas. Oriental bittersweet can hybridize with the relatively rare American bittersweet [PIER ed.: Celastrus scandens L.], potentially threating the genetic identity of American bittersweet." (Kaufman & Kaufman 2007, p. 207-208)

Clematis terniflora has been reported as a weed. (GRIN)

Clematis terniflora has become established ("naturalized") in the United States. (GRIN)

Presence:

Pacific
Country/Terr./St. & Island group	Location	Cited status & Cited as invasive & Cited as cultivated & Cited as aboriginal introduction?	Reference & Comments
State of Hawaii Hawaiian Islands	O‘ahu Island		Consortium of Pacific Herbaria (2018)
New Zealand (offshore islands) Poor Knights Islands	Aorangi 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
Asia Asia	Asia (east)	native	Seiler, John/Jensen, Edward/Niemeira, Alex/Peterson, John (2018) "Native to east Asia...."
Japan Japan	Japan	invasive	Holm, Leroy/Pancho, Juan V./Herberger, James P./Plucknett, Donald L. (1979) (p. 90) (C)ommon weed; cited as both Clematis maximowicziana and Clematis terniflora
New Zealand New Zealand	South Island		Consortium of Pacific Herbaria (2018)
United States (west coast) United States (west coast states)	USA (California)	introduced invasive cultivated	Seiler, John/Jensen, Edward/Niemeira, Alex/Peterson, John (2018) "Native to east Asia, planted in zones 4-6,and widely naturalized."

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 invasive cultivated	Seiler, John/Jensen, Edward/Niemeira, Alex/Peterson, John (2018) "Native to east Asia, planted in zones 4-6,and widely naturalized."
United States (continental except west coast) United States (other states)	United States (other states)	introduced invasive cultivated	Seiler, John/Jensen, Edward/Niemeira, Alex/Peterson, John (2018) "Native to east Asia, planted in zones 4-6,and widely naturalized."

Control:  "Vines can be pulled or dug up or cut repeatedly. The herbicides 2,4-D and triclopyr among others are used to treat [Clematis terniflora]." (Kaufman & Kaufman 2007, p. 226)

"Cut plants will send up suckers from the roots, but reprouts can then be sprayed with triclopyr. Small plants are easily hand pulled in loose soil. If vines have climbed high into trees, cut plants at 4 to 5 ft. and again at ground level to prevent resprouns from climbing old vines and to prevent harm to the tree from pulling off vines. Weekly mowing will also discourage plants." (Kaufman & Kaufman 2007, p. 208)