https://www.massey.ac.nz/about/colleges-schools-and-institutes/college-of-sciences/our-research/themes-and-research-strengths/plant-science-research/new-zealand-weeds-database/willow-weed/
Willow weed (Persicaria maculosa) has leaves similar to a willow tree and grows clusters of small pink flowers.
willow weedmassey university