Japanese Knotweed Shoots
Reynoutria japonica
Japanese Knotweed (Reynoutria japonica, formerly Fallopia japonica) is a large, herbaceous perennial in the family Polygonaceae, infamous as one of the world's most destructive invasive species — yet its young spring shoots are a delicious, tart vegetable with a flavor similar to rhubarb. This paradoxical plant costs billions in eradication efforts globally while simultaneously being harvested as a gourmet wild food by foragers who see it as "eating the enemy."
• Listed among the world's 100 worst invasive species by the IUCN
• Young shoots taste remarkably like rhubarb and can be used in pies, jams, and sauces
• The plant can grow through concrete, asphalt, and building foundations, causing structural damage
• In Japan, its native range, it is a harmless component of natural ecosystems
• Contains resveratrol — the same antioxidant compound found in red wine
• Some foraging advocates argue the best way to control it is to eat it
• In its native range, grows on volcanic slopes, riverbanks, and disturbed mountain areas
• Introduced to Europe in the 1840s by the German botanist Philipp von Siebold as an ornamental plant
• Also introduced to North America in the late 1800s as an ornamental and erosion-control plant
• Now invasive across Europe, North America, Australia, and New Zealand
• In the UK, it is illegal to plant or cause Japanese knotweed to grow in the wild
• First described by the French botanist Houttuyn in 1777 as Polygonum cuspidatum
• Has caused more property damage in the UK than any other plant species
• The cost of UK eradication efforts exceeds £150 million annually
Stems:
• Erect, hollow, bamboo-like, 2 to 4 cm in diameter
• Green with red-purple speckles, smooth
• Swollen at the nodes (characteristic of Polygonaceae)
• Die back to ground level each winter
Leaves:
• Broadly ovate to truncate at the base, 8 to 15 cm long and 5 to 12 cm wide
• Bright green, flat, with a slightly truncate (squared-off) base
• margins entire, veins prominent beneath
• Alternate arrangement
• Ochrea (papery sheath) at each node
Flowers:
• Small, creamy-white, 4 to 6 mm
• Born in large, showy, arching panicles 6 to 15 cm long
• Five tepals, white to greenish-white
• Late summer to early autumn bloom
Roots:
• Extensive rhizome system extending 2 to 3 meters deep and 7 meters laterally
• Rhizomes capable of regenerating from fragments as small as 1 cm
• Per 100 g young shoots: approximately 25 to 35 kcal
• Contains vitamins A and C
• Good source of potassium, phosphorus, and zinc
• Notably rich in resveratrol (the antioxidant compound in red wine)
• Contains emodin and other anthraquinone compounds
• Provides dietary fiber
• Low in calories and fat
• The resveratrol content is among the highest of any commonly consumed plant
• In many countries, it is ILLEGAL to plant Japanese knotweed
• For foraging only: harvest young shoots from established invasive stands in early spring
• Shoots should be 15 to 30 cm tall, tender, and easy to snap
• Peel the fibrous outer layer if shoots are slightly older
• Do not spread root or rhizome fragments — even tiny pieces can establish new colonies
• All plant waste must be disposed of properly (burned or bagged for landfill), not composted
• Check local regulations before harvesting
• The best approach to knotweed is eradication, not cultivation
• If found growing near your property, contact local invasive species authorities
• Young spring shoots are peeled and cooked like rhubarb or asparagus
• Used in pies, crumbles, and jams with a tart, rhubarb-like flavor
• Can be made into wine, similar to rhubarb wine
• Sautéed with garlic and butter as a vegetable side dish
• Added to soups and stews for tartness
• Pureed into sauces and chutneys
• The tart flavor pairs well with strawberries and apples
• Used in "knotweed gin" and other craft beverages
• Young leaves are also edible but less commonly eaten
• Always COOK shoots before eating to neutralize oxalic acid content
Fun Fact
Japanese knotweed can grow through concrete at a rate of up to 20 cm per day in spring — but foragers have the last laugh by turning this destructive invader into delicious pies
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