Family: knotweeds (Polygonaceae)
Flowering time: June–September
Size: in water up to 3 m in length, on land 30–70 cm
Habitat: moist and wet soils, in shallow waters
Water knotweed (Polygonum amphibium) is a perennial with a strong rhizome. Stamens protrude from its 4–5 mm long pink flowers, which are grouped in a dense panicle at the top of the stem. It is an amphibious plant, meaning that it can thrive well both on flooded soils and on dry land. It adapts to environmental changes by changing the shape, structure, and function of its organs. For the aquatic form, the leaves are up to 10 cm long, glabrous, lanceolate, and floating. Plants that grow on land, however, develop narrower, protruding leaves up to 20 cm long and with clasping leaf bases. It is more common in the northeastern part of Slovenia. In Slovenia it is listed as a vulnerable species.
