Japanese Knotweed

(Reynoutria japonica)

Japanese Knotweed (Reynoutria japonica)

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Estimated Native Range
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Summary

Reynoutria japonica, commonly known as Japanese Knotweed, is a deciduous perennial herb originally from East Asia, including Japan, China, and Korea, where it is found in a variety of habitats such as volcanic terrains, along riverbanks, roadsides, and open grasslands. It can grow to a height of 3–4 m (10–13 ft) each season, with a deep, extensive rhizome system. The plant has hollow stems with distinct raised nodes that give it the appearance of bamboo, though it is not closely related. Its leaves are broad, ovate, and can be up to 15 cm (6 in) in length. The small, cream or white flowers are produced in erect racemes during late summer and early autumn and are not particularly showy.

Japanese Knotweed is noted for its rapid growth and ability to colonize disturbed areas, making it a concern for natural habitats. Its ability to sprout from small sections of rhizomes makes it difficult to eradicate. In cultivation, it is used for soil stabilization and ornamental purposes due to its lush foliage. However, its invasive nature has led to it being banned or restricted in many areas. It thrives in a range of soil types and light conditions, from full sun to part shade, but prefers moist, well-drained soils. While young stems are edible, resembling rhubarb in flavor, its aggressive spread can cause damage to building foundations, roads, and flood defenses. Gardeners should be cautious and consider local regulations before planting.CC BY-SA 4.0

Plant Description

  • Plant Type: Herb
  • Height: 6-10 feet
  • Width: 3-20 feet
  • Growth Rate: Rapid
  • Flower Color: Cream, Green, White
  • Flowering Season: Summer, Fall
  • Leaf Retention: Deciduous

Growth Requirements

  • Sun: Full Sun
  • Water: Medium
  • Drainage: Fast, Medium, Slow

Common Uses

Bird Garden, Deer Resistant, Drought Tolerant, Edible*Disclaimer: Easyscape's listed plant edibility is for informational use. Always verify the safety and proper identification of any plant before consumption.

Natural Habitat

Native to a variety of habitats in East Asia, including volcanic terrains, riverbanks, roadsides, and open grasslands

Other Names

Common Names: Asian Knotweed , Japanese Knotweed , Mexican-Bamboo , Japan-Pileurt , Japanischer Flügelknöterich , Japanischer Staudenknöterich , Japanintatar , Parkslirekne , Parkslide , Rosenslide

Scientific Names: Reynoutria japonica , Polygonum cuspidatum , Fallopia japonica , Polygonum japonicum , Polygonum reynoutria , Fallopia japonica var. uzenensis , Fallopia japonica f. colorans , Reynoutria japonica var. uzenensis , Tiniaria japonica , Reynoutria japonica var. terminalis

GBIF Accepted Name: Reynoutria japonica Houtt.