Persicaria lapathifolia (L.) Gray

Pale Knotweed

Nat. Arr. Brit. Pl. 2: 270 (1821) APNI

Taxonomic status:Accepted

Occurrence status:Present

Establishment means:Uncertain

Erect or ascending annual or biennial to c. 1.6 m high, stems usually glabrous, sometimes densely cottony, often swollen about the lower nodes. Ochreas not ciliate at apex, glabrous or with cottony hairs on sheath. Leaves lanceolate, 6–12 cm long, 8–45 mm wide, margins and main veins with short antrorsely appressed bristles, lamina glabrous or cottony-pubescent, usually densely gland-dotted on lower surface, less glandular above; petiole c. 5–15 mm long. Spikes slender, cylindric, 2–7 cm long, 4–7 mm diam., often several in a terminal, sometimes drooping panicle; peduncle c. 0.5–3 cm long; perianth segments 1.5–3 mm long, pink, often pale or greenish, free for half to two-thirds their length. Nut broadly ovate to almost orbicular, flattish, c. 2 mm long and wide, slightly roughened and dull or shining, brown. Flowers Sep.–May.

CVU, EGL, EGU, GipP, Gold, HNF, HSF, MuF, MuM, MSB, NIS, OtP, OtR, RobP, VRiv, VVP. All States. It is variously treated as native or naturalised in the other jurisdictions in which it occurs. Europe, Asia, northern Africa. Widespread along permanent watercouses and in winter-wet areas, particularly in cooler parts of the State. Often occurring in disturbed or weedy areas.

Source: Walsh, N.G. (1996). Polygonaceae. In: Walsh, N.G.; Entwisle, T.J. (eds), Flora of Victoria Vol. 3, Dicotyledons Winteraceae to Myrtaceae. Inkata Press, Melbourne.
Updated by: Val Stajsic, 2018-03-14
Hero image
Distribution map
life Life
kingdom Plantae
phylum Tracheophyta
superorder Caryophyllanae
family Polygonaceae
genus Persicaria
Higher taxa


Source: AVH (2014). Australia's Virtual Herbarium, Council of Heads of Australasian Herbaria, <>. Find Persicaria lapathifolia in AVH ; Victorian Biodiversity Atlas, © The State of Victoria, Department of Environment and Primary Industries (published Dec. 2014) Find Persicaria lapathifolia in Victorian Biodiversity Atlas
  Bioregion Occurrence status Establishment means
Murray Mallee present uncertain
Victorian Volcanic Plain present uncertain
Victorian Riverina present uncertain
Murray Scroll Belt present uncertain
Robinvale Plains present uncertain
Murray Fans present uncertain
Gippsland Plain present uncertain
Otway Plain present uncertain
Goldfields present uncertain
Central Victorian Uplands present uncertain
Northern Inland Slopes present uncertain
East Gippsland Lowlands present uncertain
East Gippsland Uplands present uncertain
Highlands-Southern Fall present uncertain
Highlands-Northern Fall present uncertain
Otway Ranges present uncertain

State distribution

Distribution map
Western Australia
Northern Territory
South Australia
New South Wales
Australian Capital Territory