Fauna
Plant · GBIF taxon 2889173

Japanese Knotweed

Reynoutria japonica

Also known as Asian Knotweed, Fleeceflower, Donkey Rhubarb

Japanese knotweed forms dense, impenetrable thickets of hollow, bamboo-like stems adorned with reddish speckles and broad shield-shaped leaves. Rising rapidly each spring from massive underground rhizome networks, it smothers native vegetation and can even penetrate concrete or asphalt. Delicate sprays of creamy white flowers bloom in late summer, providing abundant late-season nectar for honeybees before foliage dies back in winter.

InvasiveFloweringPerennial
Japanese Knotweed reference1 / 7
Licensed reference(c) Douglas Goldman, some rights reserved (CC BY-SA), uploaded by Douglas Goldman · cc-by-sa
—observations
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Not EvaluatedConservation statusIUCN Red List categoriesLCNTVUENCREWEXNot Evaluated — not placed on the risk ladderRed List categories, explained →
Key facts
Diet & prey
  • Autotrophic (Photosynthetic)
Predators
  • Knotweed Psyllid
  • Grazing Livestock
ThreatsHerbicides, mechanical excavation, biological control agents
HabitatsRiparian zones, roadsides, riverbanks, disturbed urban soil
Life spanPerennial (rhizomes survive for decades)
Classification
  1. OrderCaryophyllales
  2. FamilyPolygonaceae
  3. GenusReynoutria
  4. SpeciesReynoutria japonica
Range & activity
Range data is not available yet.
Safe observation
Interaction riskLow
  1. Low
  2. Moderate
  3. High
  4. Very high
Why interaction risk is low
Safe to observe at a normal distance; wild plants have toxic look-alikes, so never ingest unverified foliage.
Responsible observation
  • Identification: Look for hollow, bamboo-like green stems with red spots and zig-zagging branch patterns.
  • Management: Avoid composting stem or root cuttings, as tiny fragments easily root and create new colonies.
  • Seasonal Timing: Look for feathery white flower plumes covering dense thickets during late August and September.
Related species
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