Smartweed (aka. Lady's Thumb Smartweed) is in the buckwheat family and has clusters of bright pink to purple flowers June to October. Wasps and bees will visit to pollinate. It thrives in damp, shady places in any kind of soil. It can form colonies spreading by seed, instead of rhizomes. Leaves sometimes have interesting dark "smudges" on the tops of the leaves.
Pot size: 4"
Mature size: 6 inches to 2 feet tall, 2+ feet wide (spreads)
Light requirements: Part sun, shade