Persicaria amphibia Care Guide
Persicaria amphibia (water knotweed, Polygonaceae) is an amphibious Holarctic herb with floating leaves and pink flower spikes, tolerating cool water.
Overview
Persicaria amphibia is a flowering plant of the knotweed family Polygonaceae, commonly called water knotweed or amphibious bistort. It is a rhizomatous perennial herb that occurs as aquatic, semi-aquatic and terrestrial forms. Aquatic individuals produce elongated floating leaves and dense terminal clusters of pink flowers.
Taxonomy
- Family: Polygonaceae
- Genus: Persicaria
- Scientific name: Persicaria amphibia
- Common name: Water Knotweed
Habitat
The species is native across the northern hemisphere (Holarctic), including Europe, Asia, North America and parts of Africa, and is introduced to South America and other regions. It thrives in wet habitats such as ponds, streams and marshes. Stems may creep, float or grow erect, rooting at the nodes, and reach up to 3 m in aquatic plants; lance-shaped leaves can exceed 30 cm.
Aquarium requirements
- Temperature: 15-26 °C (59-79 °F)
- pH: 6.0-8.0
- GH: 4-18 °dGH
- Lighting: medium
- CO2: not required
- Maximum height: up to about 60 cm
- Placement: background
Growth and care
Persicaria amphibia tolerates cool water and a wide range of conditions, reflecting its amphibious nature. It is well suited to ponds and cooler aquariums and can transition between submerged and emergent growth depending on water level.
Propagation
Propagation is by cuttings and by its creeping rhizome, which roots at the nodes to form new shoots.