Plant DetailShow Menu

Similar but less problematic plants:
Viburnum lentago Flowering form
Reynoutria japonica is often confused with:
Persicaria orientalis Polygonum orientale
Native alternative(s) for Reynoutria japonica:
Clethra alnifolia Clethra alnifolia
Cornus sericea Cornus sericea (C. stolonifera)
Itea virginica Itea virginica
Plants that fill a similar niche:
Persicaria perfoliata
Alliaria petiolata Alliaria petiolata
Pueraria montana var. lobata Pueraria lobata

Japanese Bamboo Reynoutria japonica

Previously known as:

  • Fallopia cuspidatum
  • Fallopia japonica
  • Pleuropterus cuspidatus
  • Polygonum cuspidatum
Phonetic Spelling
RAY-nu-tree-AH juh-PON-ih-kuh
This plant is an invasive species in North Carolina
Description

Asian Knotweed is a herbaceous perennial plant of the knotweed and buckwheat family and is native to Asia. In North America and Europe, it has rapidly established itself and is considered invasive in many places including North Carolina where it is found in a few coastal counties and 3 counties near Tennesse. It spreads very quickly by rhizomes and can come up in roads and foundations.

The hollow stems have raised nodes that give it the look of bamboo but it is not related. It dies to the ground in winter and new growth is reddish. Flowering occurs in late summer to fall on erect panicles.  

Please do not plant this invasive plant.

Insects, Diseases, and Other Plant Problems: Asian Knotwood spreads by strong underground stems (creeping rhizomes) that can damage foundations, roads, walls, and other structures. It quickly spreads to dominate and ecosystem and can be particularly problematic in riparian areas where the dead stems can accumulate and cause flooding or it can contribute to streambank erosion. Please avoid this plant.

Quick ID:

  • Upright stems are hollow and resemble bamboo
  • Leaves are heart to triangular shaped and alternate
See this plant in the following landscape:
Cultivars / Varieties:
  • var. compacta
    Less weedy than the species but still not recommended
var. compacta
Tags:
#invasive#weed#edible weed#weedy#high maintenance#stream banks#fast growing#aggressive#disturbed areas#edible garden#roadside
 
Cultivars / Varieties:
  • var. compacta
    Less weedy than the species but still not recommended
var. compacta
Tags:
#invasive#weed#edible weed#weedy#high maintenance#stream banks#fast growing#aggressive#disturbed areas#edible garden#roadside
  • Attributes:
    Genus:
    Reynoutria
    Species:
    japonica
    Family:
    Polygonaceae
    Uses (Ethnobotany):
    Used in Asian herbal medicine
    Life Cycle:
    Perennial
    Country Or Region Of Origin:
    Eastern Asia
    Edibility:
    Young stems are edible with a sour rhubarb flavor.
    Dimensions:
    Height: 10 ft. 0 in. - 12 ft. 0 in.
    Width: 3 ft. 0 in. - 20 ft. 0 in.
  • Whole Plant Traits:
    Plant Type:
    Edible
    Herbaceous Perennial
    Weed
    Habit/Form:
    Arching
    Growth Rate:
    Rapid
    Maintenance:
    High
  • Cultural Conditions:
    Light:
    Full sun (6 or more hours of direct sunlight a day)
    Soil Drainage:
    Moist
    Occasionally Wet
    Available Space To Plant:
    6-feet-12 feet
    12-24 feet
  • Fruit:
    Fruit Color:
    Cream/Tan
    Fruit Type:
    Achene
    Fruit Description:
    Small winged triangular achene with small shiny dark brown to black triangular shaped seeds.
  • Flowers:
    Flower Color:
    Cream/Tan
    Green
    White
    Flower Inflorescence:
    Panicle
    Spike
    Flower Bloom Time:
    Fall
    Summer
    Flower Petals:
    4-5 petals/rays
    Tepals
    Flower Size:
    < 1 inch
    Flower Description:
    Small creamy-white flowers with 5 tepals in 3-6 inch long erect panicles from the leaf axils in later summer to fall. Male and female flowers are on separate plants with the male flowers being more erect and the female flowers drooping.
  • Leaves:
    Leaf Color:
    Green
    Red/Burgundy
    Leaf Type:
    Sheath
    Simple
    Leaf Arrangement:
    Alternate
    Leaf Shape:
    Deltoid
    Elliptical
    Subcordate
    Leaf Margin:
    Entire
    Hairs Present:
    No
    Leaf Length:
    3-6 inches
    Leaf Description:
    4 to 6 inches long and 2-4 inches wide broadly oval, to triangular, sharply pointed, alternate leaves with truncated bases and entire margins. Leaves are dark green on top and light green below with reddish veins. Where they meet the stem there is a sheath-like structure called an ochrea. New growth is red.
  • Stem:
    Stem Color:
    Brown/Copper
    Green
    Red/Burgundy
    Stem Is Aromatic:
    No
    Stem Cross Section:
    Round
    Stem Description:
    Stems are green to reddish-brown large, hollow, slightly rideged lengthwise, jointed and mottled. They resemble bamboo and remain after the plant has died back to the ground.
  • Landscape:
    Problems:
    Invasive Species
    Weedy