Fallopia convolvulus

Black-bindweed is a herbaceous vine growing to 1–1.5 m (39–59 in) long, with stems that twine clockwise round other plant stems. The alternate triangular leaves are 1.5–6 cm long and 0.7–3 cm broad with a 6–15 (–50) mm petiole; the basal lobes of the leaves are pointed at the petiole. The flowers are small, and greenish-pink to greenish white, clustered on short racemes. These clusters give way to small triangular achenes, with one seed in each achene.[2][3][4][7] The flowers have 5 sepals, the 3 outer ones are larger and show a keel. It has 5 stamens and the fruit grows to 4 mm long.[8]

While it superficially resemble bindweeds in the genus Convolvulus there are many notable differences; it has ocrea (stipule-sheath at nodes), which Convolvulus does not; and Convolvulus has conspicuous trumpet-shaped flowers while Black-bindweed has flowers that are unobtrusive and only about 4 mm long.[5]

Fallopia convolvulus grows most commonly on disturbed or cultivated land, in northern Europe typically on warm, sunny, well-drained sandy or limestone soil types,[5][7] but in hotter, drier areas like Pakistan, on moist shady sites.[4] It ranges from sea level in the north of its range, up to 3600 m altitude in the south in the Himalaya.[3][4][5]

The seeds are edible, and were used in the past as a food crop, with remains found in Bronze Age middens.[5] The seeds are too small and low-yielding to make a commercial crop, and it is now more widely considered a weed, occurring in crops, waste areas and roadsides. It can be a damaging weed when it is growing in a garden or crop, as it can not only damage the plants around which it twines, but also clog the machinery used to harvest a given crop. It is also an invasive species in North America.[6]