Pennsylvania Smartweed (Polygonum Pennsylvanicum)

Polygonaceae (Buckwheat Family) 

Group: Dicot (Broadleaf)

Erect or ascending, much-branched annual herb, with swollen nodes, and a conspicuous membranous sheath surrounding the stem, native of North America. It is commonly found in cultivated fields, disturbed areas, and along ditches.

Seedling cotyledons are oblong to lance-shaped, smooth on both surfaces, with gland-tipped trichomes on the margins. Leaves are alternate, lance-shaped, pointed, with a tinge of purple, and hairy on the upper surface and margins. Stems are reddish purple, smooth, with swollen nodes. There is a papery membranous sheath (ocrea) around the swollen node at the base of leaves.

Leaves of mature plants are simple, alternate, lance- or egg-shaped, pointed, 2 to 6 inches long, up to 1-1/5-inch wide, hairless except for close-lying stiff hairs on the margins. Center of the leaf often has a purple mark. Base of the leaf stalk has an ocrea.

Stem is ascending to erect, up to 4 feet tall, swollen and jointed at nodes, branching, nearly hairless, and reddish purple.

Roots are fibrous from a shallow taproot.

Propagation is by seed.