Slender Knotweed

Scientific Name:	Persicaria decipiens (syn. Polygonum minus)	Plants of Slender Knotweed by water's-edge Photo: A J Brown
Status:	Australian native, all States.
Plant Description:	Decumbent to ascending annual or perennial herb to 30 cm high. Leaves are narrow-elliptic to lanceolate (spear-shaped), from 5-12 cm long and 5-13 cm wide and often with a purple blotch near the middle of the upper surface. Flower-heads are rather lax to drooping, elongated cylindrical spikes, 2-6 cm long and 3-4 mm diameter and flower parts 1.7-2.5 mm long. The fruit is a dark brown to black, lens-like or triangular nut, 1.5-2 mm long.
Habitat:	Semi-aquatic plants of freshwater environments. Grows in water and on wet flats at the edges of rivers, lagoons and lakes and in marshes, swamps and drainage lines. High waterlogging tolerance.
Comments:	Slender Knotweed belongs to a group of about 10 species which were once treated as part of the genus Polygonum. The four species left in Polygonum are mainly introduced plants which frequent waste ground or weeds of cropping ground and are not associated with waterlogged situations. Other Knotweeds of wide distribution, include the Australian native Spotted Knotweed (Persicaria praetermissa), Creeping Knotweed (P. prostrata), Water-pepper (P. hydropiper) and Pale Knotweed (P. lapathifolia). The introduced Persicaria or Redshank (P. maculosa) is a common weed of waterbodies in Gippsland. Its flower-spikes and shorter and broader than in Slender Knotweed

Slender Knotweed Photos

Branch of Slender Knotweed Photo: A J Brown	Flowers of Slender Knotweed Photo: A J Brown
Leaves and flower spikes of Slender Knotweed Photo: A J Brown	Older leaves of Slender Knotweed Photo: A J Brown
Developing flower spike of Slender Knotweed Photo: A J Brown	Young leaves of Slender Knotweed Photo: A J Brown

Page top