Fowler's Knotweed

Plants green, sometimes purple tinged, homophyllous or hetero-phyllous, sometimes subsucculent. Stems prostrate to ascending, sometimes zigzagged, branched from base, not wiry, 5-50 cm. Leaves: ocrea 2.5-12 mm, proximal part funnelform, distal part soon disintegrating, nearly completely deciduous or fibers persistent; petiole 2-7 mm; blade light green, sometimes purple tinged, elliptic to elliptic-obovate or obovate, 8-30(-50) × 4-15(-25) mm, margins flat, apex acute to obtuse; middle stem leaves 1.1-2.1(-3.4) times as long as adjacent branch leaves, distal leaves overtopping flowers. Inflorescences axillary; cymes uniformly distributed, 1-7(-10)-flowered. Pedicels enclosed in or sometimes exserted from ocreae, 1-2.5 mm. Flowers closed; perianth (2.2-)2.5-4.5 mm; tube 23-38% of perianth length; tepals initially overlapping, pushed apart as achene develops, green, margins white to pink, petaloid, not keeled, oblong, cucullate; midveins branched, sometimes not visible; stamens 6-8. Achenes exserted from perianth, brown to dark brown, broadly ovate to ovate-lanceolate, (2-)3-gonous, (1.8-)2-3.7(-4.5) mm, faces subequal or unequal, flat to concave, apex beaked, edges strongly concave, shiny to dull, roughened, rarely obscurely tubercled; late-season achenes common, 4-6 mm.