polygonum

Polygonum is a genus of flowering plants in the family Polygonaceae. This genus is widespread, found across temperate regions of the Northern Hemisphere. Plants in the Polygonum genus are typically herbaceous annuals or perennials, though some species can be shrubby. They are characterized by their jointed stems and often have a sheathing membrane called an ocrea at the base of each leaf stalk. The leaves are usually simple and alternate.

The flowers of Polygonum species are typically small and inconspicuous, often borne in spikes or racemes. They are usually white, pink, or greenish. The fruit is a small, hard achene. Many species are considered weeds, particularly in agricultural settings, due to their rapid growth and ability to spread. However, some species have historical medicinal uses or are cultivated for ornamental purposes. For example, Polygonum cuspidatum, commonly known as Japanese knotweed, is a particularly aggressive invasive species in many parts of the world. Other species, like Polygonum orientale (prince's feather), have been grown for their attractive foliage and flower heads. The genus is taxonomically complex, with ongoing research to clarify species boundaries and relationships.