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black bindweed, climbing bindweed, climbing knotweed, Eurasian black bindweed, ivy bindweed

Japanese knotweed, Japanese wing-knotweed

Habit Herbs, annual, not rhizomatous, 0.5–1 m.
Stems

scandent or sprawling, branched proximally, herbaceous, puberulent, sometimes mealy, not glaucous.

Leaves

ocrea persistent or deciduous, tan or greenish brown, cylindric, 2–4 mm, margins oblique, face not fringed with reflexed hairs and slender bristles at base, otherwise glabrous or scabrid;

petiole 0.5–5 cm, puberulent in lines;

blade cordate-ovate, cordate-hastate, or sagittate, 2–6(–15) × 2–5(–10) cm, base cordate, margins wavy, scabrid, apex acuminate, abaxial face usually mealy and, rarely, minutely dotted, not glaucous, adaxial face glabrous.

Inflorescences

axillary, erect or spreading, spikelike, 2–10(–15) cm, axes puberulent;

peduncle 0.1–10 cm or absent, glabrous or scabrid distally in lines.

Pedicels

ascending or spreading, articulated distally, 1–3 mm, glabrous or, rarely, scabrid.

Flowers

bisexual, 3–6 per ocreate fascicle;

perianth nonaccrescent, greenish white, often with pinkish or purplish base, 3–5 mm including stipelike base, glabrous or outer 3 with blunt, hyaline hairs;

tepals elliptic to obovate, apex obtuse to acute, outer 3 obscurely keeled;

stamens 8;

filaments flattened proximally, glabrous;

styles connate distally;

stigmas capitate.

Achenes

included, black, 4–5(–6) × 1.8–2.3 mm, dull, minutely granular-tuberculate, especially on faces; fruiting perianth glabrous or with blunt, hyaline hairs, wings absent or, rarely, flat to undulate, 0.4–0.9 mm wide at maturity, scarcely decurrent on stipelike base, margins entire.

2n

= 40.

Fallopia convolvulus

Fallopia japonica

Phenology Flowering May–Oct.
Habitat Cultivated ground, waste places
Elevation 0-2700 m (0-8900 ft)
Distribution
from FNA
AK; AL; AR; AZ; CA; CO; CT; DC; DE; FL; GA; IA; ID; IL; IN; KS; KY; LA; MA; MD; ME; MI; MN; MO; MS; MT; NC; ND; NE; NH; NJ; NM; NV; NY; OH; OK; OR; PA; RI; SC; SD; TN; TX; UT; VA; VT; WA; WI; WV; WY; AB; BC; MB; NB; NL; NS; ON; PE; QC; SK; YT; SPM; Greenland; Eurasia [Introduced in North America; introduced in South America (Argentina, Chile), Africa (Algeria, Morocco, Republic of South Africa), Pacific Islands (Hawaii, New Zealand), Australia]
[WildflowerSearch map]
[BONAP county map]
from FNA
AK; AR; CA; CO; CT; DC; DE; GA; IA; ID; IL; IN; KS; KY; LA; MA; MD; ME; MI; MN; MO; MS; MT; NC; NE; NH; NJ; NY; OH; OK; OR; PA; RI; SC; SD; TN; UT; VA; VT; WA; WI; WV; BC; MB; NB; NF; NS; ON; PE; QC [Asia, introduced in Europe]
[WildflowerSearch map]
Discussion

Fallopia convolvulus can be an aggressive weed in crop fields. Rare plants with winged fruiting perianths have been named var. subalata; that characteristic often varies within populations.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Varieties 4 (1 in the flora).

Fallopia japonica is planted widely as a garden ornamental; it has a proclivity to escape and spread aggressively. Once established, plants can be difficult to eradicate because of their extensive, woody rhizomes. The species has been declared noxious in Alabama, California, Oregon, Vermont, and Washington.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Source FNA vol. 5, p. 545. FNA vol. 5, p. 543.
Parent taxa Polygonaceae > subfam. Polygonoideae > Fallopia Polygonaceae > subfam. Polygonoideae > Fallopia
Sibling taxa
F. baldschuanica, F. cilinodis, F. dumetorum, F. japonica, F. sachalinensis, F. scandens, F. ×bohemica
F. baldschuanica, F. cilinodis, F. convolvulus, F. dumetorum, F. sachalinensis, F. scandens, F. ×bohemica
Subordinate taxa
F. japonica var. japonica
Synonyms Polygonum convolvulus, Bilderdykia convolvulus, F. convolvulus var. subalata, Reynoutria convolvulus, Tiniaria convolvulus Reynoutria japonica
Name authority (Linnaeus) Á. Löve: Taxon 29: 300. (1970) (Houttuyn) Ronse Decraene: Bot. J. Linn. Soc. 98: 369. (1988)
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