Fam. Pl. 2: 277, 557. 1763.
Vines or herbs, annual or perennial; roots fibrous or woody; sometimes rhizomatous. Stems erect to scandent, rarely procumbent, glabrous or pubescent. Leaves deciduous, cauline, alternate, petiolate; ocrea persistent or deciduous, chartaceous; petiole base articulated, extrafloral nectaries sometimes present; blade broadly ovate to triangular, margins entire or wavy. Inflorescences terminal and spikelike, or terminal and axillary and paniclelike or racemelike, pedunculate or not. Pedicels present. Flowers bisexual, or bisexual and unisexual, some plants with bisexual flowers, other plants with only pistallate flowers 1–5 per ocreate fascicle, base stipelike; perianth usually accrescent in fruit, pale green or white to pink, campanulate, glabrous or, rarely, with blunt, hyaline hairs; tepals 5, connate nearly completely or only basally, petaloid, dimorphic, outer 3 winged or keeled, larger than inner 2; stamens 6–8; filaments distinct, free, glabrous or pubescent proximally; anthers yellow to pink or red, ovate to elliptic; styles 3, spreading, connate basally or nearly completely; stigmas capitate, fimbriate, or peltate. Achenes included or exserted, brown to dark brown or black, not winged, 3-gonous, glabrous. Seeds: embryo straight. x = 10, 11.
North America (including Mexico), South America, Europe, Asia, Africa.
Species ca. 12 (8 in the flora).
Chromosome number and habit traditionally have been used to separate Fallopia (x = 10; climbing or sprawling, fibrous-rooted annuals and perennials) from Reynoutria (x = 11; erect, rhizomatous perennials). J. P. Bailey and C. A. Stace (1992) presented evidence to the contrary. Fallopia often is included in a broader concept of Polygonum but is distinguished by a syndrome of anatomical and morphological characters (K. Haraldson 1978; Hong S. P. et al. 1998; L.-P. Ronse Decraene and J. R. Akeroyd 1988; Ronse Decraene et al. 2000). Molecular data confirm its close relationship to Polygonum in the narrow sense (A. S. Lamb Frye and K. A. Kron 2003).
|1||Stigmas fimbriate; stems erect||> 2|
|1||Stigmas capitate or peltate; stems usually trailing, twining, scandent, sprawling, or climbing, rarely erect||> 4|
|2||Leaf blades with hairs along veins on abaxial face distinctly multicellular, 0.2-0.6 mm, bases of blades cordate||Fallopia sachalinensis|
|2||Leaf blades with hairs along veins on abaxial face unicellular or appearing so, shorter than 0.1 mm, or veins scabrous, bases of blades truncate to attenuate or cordate||> 3|
|3||Leaf blades obscurely puberulent along some veins abaxially, tips of hairs acute, bases of blades truncate to cordate||Fallopia ×bohemica|
|3||Leaf blades obscurely scabrous along some veins abaxially, tips of hairs blunt, bases of blades truncate to attenuate||Fallopia japonica|
|4||Plants perennial; stems woody, climbing||Fallopia baldschuanica|
|4||Plants annual or perennial; stems herbaceous, scandent or sprawling. [5. Shifted to left margin.—Ed.]||> 5|
|5||Ocreae bases fringed with reflexed hairs and slender bristles||Fallopia cilinodis|
|5||Ocreae bases glabrous or scabrid||> 6|
|6||Achenes minutely granular-tuberculate, dull; fruiting perianths glabrous or with blunt, hyaline hairs, wings absent or, rarely, 0.4-0.9 mm wide; plants annual||Fallopia convolvulus|
|6||Achenes smooth, shiny; fruiting perianths glabrous, wings (0.7-)1.5-2.1 mm wide; plants perennial or annual||> 7|
|7||Plants perennial or annual; fruiting perianth wings decurrent on stipelike base, undulate or crinkled, rarely flat, margins wavy-crenulate to incised or lacerate, rarely entire||Fallopia scandens|
|7||Plants annual; fruiting perianth wings usually truncate to attenuate-decurrent on stipelike base, flat or, less often, undulate or crinkled, margins entire or rarely undulate-crenate||Fallopia dumetorum|