PENNSYLVANIA SMARTWEED, Polygonum pensylvanicum L. 1, lower part of plant; 2, upper part of plant; 3, section of stem, leaf, and leaf sheath; 4, flower; 5, seed. Annual, reproducing by seeds. Stems smooth, swollen at nodes, branching, 1 to 4 feet (0.3 to 1.2 m) tall. Leaves smooth, pointed, alternate, 2 to 6 inches (5 to 15 cm) long, with a sheath at the base extending around the stem. Flowers bright pink or rose, 5-parted, arranged in a short spike. Seeds shiny, black, smooth, flattened, almost circular. Found in cultivated ground and waste places, and along ditches.

 LADYSTHUMB, Polygonum persicaria L. 6, upper part of plant; 7, section of stem, leaf, and leaf sheath; 8, seed. Annual, reproducing by seeds. Stems smooth, sometimes hairy, much-branched, 6 inches to 3 feet (15 to 90 cm) tall. Leaves alternate, pointed at both ends, 1 to 6 inches (2.5 to 15 cm) long, with smooth edges and usually a dark spot in the middle. Sheath at base of the leaf fringed with short bristles. Flowers pink or purplish. Seeds almost circular, flattened or 3-sided, smooth, black, shiny. Found in same areas as above.