Species
Reynoutria sachalinensis
Common Name(s)
giant knotweed
Family
Polygonaceae
Flora Category
Vascular - Exotic
Structural Class
Dicotyledonous Herbs other than Composites
Habitat
Terrestrial.
Features
Giant rhizomatous herb forming large thickets; stems glabrous, green, 2~4m high, approx. 2cm diam., woody at base. Petiole 2~6cm long, often reddish, channelled above, with 3 pits at base on dorsal side, except in some infl. leaves. Lamina 10~30 x 5~22cm, broad- to oblong-ovate, glaucescent below, entire to undulate, usu. 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 6cm long, glabrous, soon deciduous. Panicle branches solitary or fascicled, at least the lower branches <= petioles, erect to spreading, densely puberulent. Bracts small, generally puberulent, acuminate or long-cuspidate. Pedicels .5~3mm long, glabrous, jointed in lower half. Perianth 1~2mm long at antithesis (excl. basal decurrent wing), white or greenish-white; segments broad-obovate or oblong-obovate, keeled. Filaments to about 1.5mm long. Stigmas fimbriate. Fruit valves prominently winged. Nut invisible. (-Webb et. al., 1988)
Flowering
November, December, January, February, March, April
Flower Colours
Green,White
Year Naturalised
1935
Origin
E Asia, N Japan
Reason For Introduction
Ornamental
Life Cycle Comments
Perennial.
This page last updated on 18 Jan 2010