pink-weed ? Obs. [f. pink n.4or a.1 + weed n.] Knotgrass, Polygonum aviculare. 1657W. Coles Adam in Eden ccxxi. 348 It is called..in English Knot-Grasse..: some also call it Pink-Weed, and some Nine Joynts of its great number of Joynts.1866Treas.Bot., Pink-weed, Polygonum aviculare.