Description: Rhizomatous perennials with stout erect annual stems; functionally dioecious.
Leaves petiolate, articulate; pit nectaries present; ocrea short-tubular, pale brown, membranous, entire, soon disintegrating.
Flowers functionally unisexual with vestiges of the other sex usually present, clustered, forming axillary panicles. Perianth segments 5, somewhat petaloid, the outer 3 keeled and becoming winged in fruit. Stamens 8; anthers versatile. Style trifid, very short; stigmas shortly elongate, fimbriate.
Achene trigonous, shorter than and enclosed by enlarged perianth.
Distribution and occurrence: World: c. 15 species, Asia. Australia: 2 species and one hybrid (naturalized), all present in NSW
Previously included in Fallopia but recent research (e.g. Schuster et al. 2011) indicates their separate status.
Text by K. L. Wilson (1990); edited KL Wilson (Sept 2017)
Taxon concept:
| | Key to the species | |
| 1 | Mature leaves with scattered to dense multicellular hairs to nearly 1 mm long at least along the veins on the undersurface; leaf base strongly cordate, apex acute to acuminate, [15–40 cm long, 7–25 cm wide]; plants 2–5 m high | Reynoutria sachalinensis |
| Mature leaves glabrous or with sparse short hairs or minutely roughened on the undersurface; leaf base truncate to slightly cordate, apex cuspidate to acuminate; plants 1.5–5 m high | 2 |
| 2 | Mature leaves 10–30 cm long, to 18 cm wide, with sparse short hairs or small warty protuberances at least along veins on undersurface; the leaf base slightly cordate, the apex more or less acuminate; plants 2–5 m tall | Reynoutria x bohemica |
| Mature leaves 5–15 cm long, 2–12 cm wide, glabrous or minutely roughened on the undersurface; the leaf base more or less truncate, the apex long-acuminate to cuspidate; plants 1.5–3 m high
Back to 1 | Reynoutria japonica |
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