Polygonum arenastrum Boreau
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.
Species Description - Freely branching, homophyllous annual, prostrate and commonly mat-forming; lvs bluish-green, broadly elliptic to oval-oblong, obtuse or rounded, 5–20 × 3–9 mm, often deciduous in late season; ocreae 3–6 mm, bifid, eventually lacerate; mature perianth 1.8–2.6 mm, divided to about the middle, the segments with white to pink margins and flat, obtuse or rounded tip; achenes 1.5–2.3 mm, shortly included to shortly exserted, dark brown, striate- papillate, late season ones to 4 mm, olivaceous, smooth; 2n=40. Abundant weed of dooryards, sidewalks, and streets, native of Europe, now widespread in temperate N. Amer. (P. aviculare, misapplied)