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Oxford Companion to Food

Oxford Companion to Food

By Alan Davidson

Published 2014

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knotweed or knotgrass a name referring to the knotted roots of plants of the genus Polygonum, including bistort and smartweed, and Fallopia, but with special reference to Japanese knotweed, Fallopia japonica, an edible oriental herb which has been introduced to N. America; and Fallopia sachalinensis, giant Japanese knotweed, also edible.

Japanese knotweed is a vigorous plant which has made itself at home throughout the USA where its jointed, hollow stems (like bamboo, hence another name sometimes used, flowering bamboo) reach a height of 2 metres (7'). Gibbons (1962) indicated many uses for it. The young shoots make a pleasant vegetable, whose acidity can be tempered by the addition of a little sugar in the cooking. Or, they can be steamed and made into a purée, which can in turn serve as the basis of a sweetened cold soup. The mature stems, peeled, can be treated like rhubarb; and it is even possible to make a jam or pie from them.