Ladysthumb / Smartweed

Terminal portion of a smartweed plant flowering - 07/13/2004Ladysthumb (Lady’s Thumb) or Smartweed

Family: Polygonaceae (Buckwheat or Knotweed Family)

Genus: Polygonum (some sources use persicaria for the genus) | Species: persicaria, vulgaris, and/or caespitosum (Most common member of this group, at least in the northeastern US, is called Pennsylvania SmartweedPolygonum Pensylvanicum)

Description: Some may also refer to this very common weed as “Smartweed.” The leaves are distinctly pigmented in the centers. This dark green, triangle-shaped splotch was at one time thought to resemble a lady’s thumbprint; Leaves alternate, opposite, 2-6″ (5-15 cm) long and narrowly or broadly lanceolate, with a fringe of hairs along the cylindrical sheath located at each leaf base. The small, pink or purplish flowers are clustered together in spikes along a single inflorescence.  (The spike-like racemes are rather stout, erect, and densely crowded with the small flowers.) [annual]

Habitat: Roadsides, damp clearings, cultivated ground;

In Bloom: June – October

Photo showing a bunch of the leaves of a smartweed (ladysthumb) plant, with the characteristic dark pigment 'thumbprint' clearly visible at the center of each leaf. Stem and leaves of a young smartweed (ladysthumb) plant