Seeds were also present in ballasts of ships where soil was used to weigh down the vessels for stability on the ocean.
Individual flowers have five or six pink-purple petals surrounding small, yellow centers.
Each flower spike is made up of many individual flowers. There may be from 1-50 spikes per plant. 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.