Epilobium tetragonum, commonly known as the square stalked willow herb, is a species of flowering plant in the willowherb family Onagraceae.
The erect perennial herb typically grows to a height of 0.1 to 1.3 metres (0.3 to 4.3 ft) and can have several stems. It blooms between January and November[clarification needed] and produces pink-purple flowers.
The species has become naturalised in the Perth and Peel regions of Western Australia.[1]
Epilobium tetragonum is characterized by its distinctive square-shaped stem, with leaves evenly spaced in a tetragonal arrangement around the stem, giving the plant a square-like appearance. The leaves are hairless and solid green and have a unique shimmer in direct sunlight.[2]
