Each mature plant can produce up to 2.7 million seeds each year. Seed capsules appear on the lower part of the stalk while flowers at the top are still blooming. This can be as early as July. Like tiny grains of sand, seeds are easily spread by water, wind, wildlife, and people. Germination can occur the following season, but seeds may lay dormant for several years before sprouting.
Leaves are long and smooth edged.
They are arranged opposite each other on the stalk in pairs at 90 degree angles. You may see them in groups of three. Stalks are 4-6 sided with larger stems up to 6 feet tall and partially woody. Looks like swamp loosestrife, fireweed, blue vervain, winged loosestrife, blazing star, and gayfeather, but these are harmless. Look at a field guide to tell them apart.