Smartweed can be identified as a vertical or ascending multibranched broadleaf weed. Its stems are branched, green or red in color, and swollen and jointed at the nodes. The leaves are smooth with sparse hairs and are sometimes marked with a purple blotch. A membranous sheath is present at the base of the petiole. Smartweed features fibrous roots branching from a shallow taproot. In bloom, Smartweed produces small white to pinkish-colored flowers that grow singly on short stems, forming in clusters and branching from a common stem.
This broadleaf weed grows in moist and wet locations, preferring disturbed sites such as waste grounds and along roadsides and railroads. Smartweed can be found in most of the continental United States.
Proper cultural practices, such as proper mowing and watering, can help prevent Polygonum pensylvanicum by creating dense grass, which inhibits this broadleaf weed's ability to grow. Physical removal (i.e., pulling weeds) can be effective, though you run the risk of spreading the seeds to additional areas of your lawn and landscaping.