Aquatic and Wetland Vascular Plants of the Northern Great Plains
15. Polygonaceae, the Smartweed Family
1. Polygonum L. -- Smartweed, knotweed, tear-thumb9. Polygonum punctatum Ell.-- Water smartweed
Simple to branched, erect to spreading annual 3-10 dm tall. Leaf blades lanceolate, 4-10 cm long, 1-2 cm wide, glabrous except for the minutely strigose margin, usually puncticulate, especially beneath, acute or acuminate to the blunt tip, cuneate to the short-petioled base; ocreae 5-15 mm long, fringed with bristles, glabrous to strigose. Racemes usually many, slender, elongate, loosely flowered, interrupted in the lower portion, to 10 cm long. Flowers greenish-white; calyx 3-4 mm long, strongly glandular-punctate, 5-parted to about the middle; stamens 6-8, included; style branches 2-3. Achenes dark brown to black, shiny, lenticular or trigonous, 2-3 mm long. Aug--Sep. Shores and stream banks; uncommon in s ND to frequent in NE; (Throughout most of N.Amer., s to S.Amer.).
Previous Species -- Polygonum persicaria L.-- Lady's thumb
Return to Family -- Polygonaceae - The Smartweed Family
Next Species -- Polygonum ramosissimum Michx.-- Bushy knotweed
