Polygonum hydropiper Linnaeus, Species Plantarum 1: 361. 1753.

"Habitat in Europae subhumidis." RCN: 2859.

Lectotype (Bhopal & Chaudhri in Pakistan Syst. 1(2): 76. 1977): Herb. Linn. No. 510.9 (LINN) .

Current name: Persicaria hydropiper (L.) Spach ( Polygonaceae).

Note: Ekman & Knutsson (in Nordic J. Bot. 14: 24. 1994) assessed the identities of the original material for this name and designated Herb. Clifford: 42, Persicaria 4 (BM) as lectotype, a choice that maintained the traditional usage of the name. They noted that 510.9 (LINN), part of the original material, was identifiable as Persicaria minor (Huds.) Opiz, but were unaware that Bhopal & Chaudhri had already designated this collection as the type. If this identification is confirmed, P. hydropiper would seem likely to be a candidate for conservation.