Fallopia sachalinensis (F.Schmidt) Ronse Decr.

Giant rhizomatous herb forming large thickets; stems glabrous, green, 2–4 m high, c. 2 cm diam., woody at base. Petiole 2–6 cm long, often reddish, channelled above, with 3 pits at base on dorsal side except in some infl. lvs. Lamina 10–30–(40) × 5–22–(30) cm, broad- to oblong-ovate, glaucescent below, entire to somewhat undulate, usually glabrous when mature, or sometimes puberulent towards base of veins on upper side, with > 14 pairs of lateral veins; base shallow- to deep-cordate; sinus wide; apex acute to cuspidate. Ochreae to 6 cm long, glabrous, soon deciduous. Panicle branches solitary or fascicled, at least the lower branches < or = petioles, erect to spreading, densely puberulent. Bracts small, ± puberulent, acuminate or long-cuspidate. Pedicels 0.5–3 mm long, glabrous, jointed in lower 1/2. Perianth 1–2 mm long at anthesis (excluding basal decurrent wing), white or greenish white; segments broad- or oblong-obovate, keeled. Filaments to c. 1.5 mm long. Stigmas fimbriate. Fr. valves prominently winged. Nut not seen.

[From: Webb et al. (1985) Flora of New Zealand. Volume 4 as Reynoutria sachalinensis (F.Schmidt) Nakai]