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POLYGONUM
Polygonum is a genus in the buckwheat family Polygonaceae. The name is probably derived from the Greek poly, "many" and gonu, "knot". There is another theory which states that the second part of the name is derived from Greek gonos, "children". Common names include knotweed, knotgrass, bistort and several others.
The genus primarily grows in northern temperate regions. They vary widely from prostrate herbaceous annual plants under 5 cm high, others erect herbaceous perennial plants growing to 3–4 m tall, and yet others perennial woody vines growing to 20–30 m high in trees; several are also aquatic, growing as floating plants in ponds. The smooth-edged leaves vary greatly in shape between species, and can be narrow lanceolate, oval, broad triangular, heart shaped or arrowhead shaped; they range from 1–30 cm long. The stems are often reddish or red-speckled. The flowers are small, pink, white, or greenish, forming in summer in dense clusters from the leaf joints or stem apices.
Polygonum species are used as food plants by the larvae of some Lepidoptera species - see list of Lepidoptera which feed on Polygonum.
Species
Between 150–300 species are recognised depending on the circumscription of the genus; some botanists divide the genus up into several smaller genera, including Fagopyrum, Fallopia and Persicaria. Selected species include:
Reclassified as Fagopyrum
Reclassified as Fallopia
Reclassified as Persicaria
References/External links
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