Purple loosestrife

Description:

L. salicaria is a herbaceous, wetland perennial that grows in a wide range of habitats. Established plants can reach heights of 2m with 30-50 stems forming wide-topped crowns that dominate the herbaceous canopy. One mature plant can produce more than 2 million seeds annually. Seeds are easily dispersed by water and in mud adhered to aquatic wildlife, livestock and people. High temperatures (>20°C) and open, moist soils are required for successful germination and seedling densities can approach 10,000-20,000 plants/m2. A woody rootstock serves as a storage organ, providing resources for growth in spring and regrowth if the above-ground shoots are cut or damaged.

Notes:

Considered an invasive species in the US