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Reynoutria sachalinensis
Also called Sakhalin Knotweed, Sachaline Knotweed, Sacaline, Elephant Ear
Giant knotweed is a large, fast-spreading herbaceous perennial from northeast Asia that forms dense clonal colonies from strong rhizomes. It is grown as a garden or forage plant but is best known as an aggressive invasive weed, so the key is containing its roots.
Reynoutria sachalinensis, the giant knotweed or Sakhalin knotweed (syns. Polygonum sachalinense, Fallopia sachalinensis), is a species of Fallopia native to northeastern Asia in northern Japan (Hokkaidō, Honshū) and the far east of Russia (Sakhalin and the southern Kurile Islands).
Reynoutria sachalinensis is a herbaceous perennial plant growing to 2–4 m (79–157 in) tall, with strong, extensively spreading rhizomes forming large clonal colonies. The leaves are some of the largest in the family, up to 15–40 cm (6–15.5 in) long and 10–28 cm (4–11 in) broad, nearly heart-shaped, with a somewhat wavy, crenate margin. The flowers are small, produced on short, dense panicles up to 10 cm (4 in) long in late summer or early autumn; it is gynodioecious, with male and female (male sterile) flowers on separate plants.
The shoots are tender and edible. It was introduced to Europe and grown in many botanic gardens. It came prominently into notice about 1893, when a drought in western Europe caused a decided shortage in forage for cattle. This plant was little affected, and since its tender shoots and leaves were eaten by stock, the plant was widely grown experimentally as a forage crop. It has proved less useful than was predicted, and its deliberate cultivation has been almost entirely abandoned. It has, however, like F. japonica, proved to be an invasive weed in several areas.
It has hybridised with Reynoutria japonica in cultivation; the hybrid, Reynoutria × bohemica (Chrtek & Chrtková) J.P.Bailey, is frequently found in the British Isles and elsewhere.
Chinese Fleeceflower · Bohemian knotweed · Japanese Knotweed
Text excerpted from the Wikipedia article Reynoutria sachalinensis by its contributors, under CC BY-SA 4.0; the excerpts and the care summary drawn from them are shared under the same licence.
The care summary was written by AI (Claude, Anthropic) from the sources on this page, with general growing knowledge where they are silent. Check before relying on it.
Life form, climate and native range: World Checklist of Vascular Plants, Royal Botanic Gardens, Kew (CC BY 3.0), reformatted; see Plants of the World Online.
