Broadleaf Knotweed

Herbs. Stems prostrate to erect, often zigzagged, reddish brown, simple or branched from base, wiry, 2-30 cm, papillose-scabrid-ulous. Leaves evenly distributed or crowded at branch tips, arti-culated to ocreae, basal leaves persistent, hardly reduced distally; ocrea 1-4 mm, papillose-scabridulous, proximal part cylindric, distal part entire or dentate-lacerate; petiole 0.1-3 mm; blade 1-veined, not pleated, narrowly elliptic, elliptic, ovate, obovate, or subround, 6-27 × 3-8 mm, margins flat, smooth, irregularly thickened or papillose-denticulate, apex apiculate, green adaxially. Inflorescences axillary; cymes from near stem and branch bases, sometimes also crowded at branch apices, 1-3-flowered. Pedicels enclosed in ocreae, erect to spreading, 2-3 mm. Flowers semi-open or closed; perianth 1.8-2.5 mm; tube 22-29% of perianth length; tepals overlapping, greenish with narrow white or pink margins, almost sepaloid, oblong, cucullate, ± navicular, apex rounded; midveins thickened, unbranched; stamens 8. Achenes enclosed in perianth or tip exserted, black, elliptic to ovate, 1.8-2.3 mm, faces subequal, smooth, shiny.

Alta., B.C.; Alaska, Calif., Colo., Idaho, Mont., Nev., Oreg., Utah, Wash., Wyo.

Flowering Jul-Sep.

Alpine to subalpine sites, open or semibarren soil; 1500-3300m.

Polygonum torreyi S. Watson