Japanese clematis is a weedy, twining perennial vine in the buttercup family Ranunculaceae that is native to Japan, Korea and central and southern China. The epithet is Latin for “having flowers in groups of three.” While it can be beautiful, Japanese clematis is a vigorous grower in full sun or partial shade and spreads by self-seeding, layering, and runners. It may rapidly reach 15 to 30 feet high and wide. It has escaped cultivation to invade forest edges, right-of-ways, and areas along streams and roads. It climbs other vegetation, forming dense blankets that block sunlight to the plants underneath. The showy white flowers appear in late summer. It is considered an invasive species in some states in the eastern US. Because it is an aggressive weed, it is not recommended for any garden. Insects, Diseases, and Other Plant Problems: This is a weedy and poisonous species, so alternatives should be considered for landscaping. Please see the suggestions in the left-hand column. This plant is listed as invasive by the NC Invasive Plant Council. Common problems include aphids, vine weevils, leaf spot, stem rot, and powdery mildew. VIDEO created by Grant L. Thompson for “ Trees, Shrubs, and Woody Vines for Landscaping ” a plant identification course offered by the Department of Horticulture at Iowa State University . More information on Clematis .
Curated pairwise relationships between this plant and others in the library — who feeds
whom, who competes, who confuses the pests. Green reads as a good pairing, red as one to avoid.
No curated interactions recorded for this species yet.
Also noted by NC State
Related species the NC State Plant Toolbox flags for this plant — look-alikes to tell
apart, and plants that play a similar role in a planting. Ones we carry in the library are linked.
Full sun (6 or more hours of direct sunlight a day) | Partial Shade (Direct sunlight only part of the day, 2-6 hours)
Soil texture
Clay; Loam (Silt)
Soil drainage
Good Drainage
Available space
12-24 feet
NC region
Coastal; Mountains; Piedmont
Mature size
Height: 15 ft. 0 in. - 30 ft. 0 in. | Width: 15 ft. 0 in. - 30 ft. 0 in.
Growth rate
Rapid
Maintenance
High
Canopy layer
6 - Vine (vertical)
Form & Appearance
Habit / form
Climbing; Dense; Spreading
Texture
Medium
Foliage
Deciduous; Semi-evergreen
Leaf color
Green
Leaf type
Compound (Pinnately , Bipinnately, Palmately)
Leaf arrangement
Opposite
Leaf shape
Cordate; Deltoid; Elliptical; Ovate
Leaf margin
Entire
Leaf feel
Glossy; Leathery
Leaf size
1-3 inches long, 1-3 inches wide
Hairs present
No
Leaf detail
3-5 leaflets with apically round and basally cordate leaflets can be toothed on young plants but are entire when mature. The long petioles of these compound leaves can lean or bend around neighboring objects for support; tendrils are not present.
Flower color
Cream/Tan; White
Flower value
Fragrant; Showy
Flower form
Panicle
Flower shape
Cross; Star
Flower size
1-3 inches
Flower detail
Flowers bloom in late summer (August) to fall (October) and are produced in terminal branching panicles of 3-12 flowers. Each monoecious flower has four pure white, narrow, petal-like sepals, approximately 50 stamens, and 5-10 pistils with long, plumose styles
Bloom time
Fall
Fruit color
Brown/Copper; Cream/Tan; White
Fruit type
Achene
Fruit value
Showy
Fruit detail
Plume-like seed heads (clusters of 5-6 fruits connected at the heads and each having a long white tail). The large achenes are ovoid and flattened in shape; they are thinly covered with appressed silky hairs.
Bark color
Light Brown
Bark detail
longitudinally shredded bark on mature stems
Stem color
Brown/Copper; Green
Stem detail
Shallowly-grooved stems grow from a tap root, starting out green and developing light brown, longitudinally shredded bark on mature stems.
Wildlife & Ecology
Native status
Non-native
Origin
Central & South China to Japan.
Distribution
It has naturalized in many parts of the USA, particularly in the East and Midwest.
Poisonous to Humans; Problem for Cats; Problem for Children; Problem for Dogs; Problem for Horses; Weedy
Resistant to
Black Walnut; Deer; Diseases; Insect Pests
Propagation
Layering; Seed; Stem Cutting
Poison severity
High
Poison parts
Leaves; Sap/Juice
Poison symptoms
Clematis can cause severe mouth pain and ulcers if eaten. Toxic to dogs, cats, horses. Clinical signs are salivation, vomiting, diarrhea. In humans, symptoms may include dizziness, confusion, fainting, and convulsions. Fatalities are rare, due to the rapid and intense bitter taste and mouth irritation from eating. Gastric lavage is recommended and anti-inflammatory to soothe irritated tissue. Contact dermatitis results in skin redness and burning sensation for some people, gardening gloves are recommended.
Toxic principle
protoanemonin
Contact dermatitis
Yes
Toxicity summary
High severity poison; parts: Leaves; Sap/Juice; contact dermatitis