Persicaria longiseta

An annual herb native from Pakistan to the Russian Far East and the Philippines, it belongs to the Polygonaceae family. Its branching stems trail near the ground or rise upward and may root at their lower nodes. The leaves are lance-shaped, and a tubular sheath at each leaf base has a fringe of long bristles. Slender, spike-like clusters bear small pink flowers. The shiny, dark brown to black fruits are three-sided. It occurs in moist woodland, pond shorelines, roadsides, and disturbed ground. It is naturalized in North America and parts of Europe, and is invasive in New England, where it can form large stands in wet, disturbed areas. Photographed in the department of Antioquia, Colombia.