Herbs, annual; taprooted. Stems decumbent, ascending, or erect, glabrous. Leaves cauline, alternate or subopposite, petiolate; ocrea persistent, chartaceous; blade spatulate-ovate to orbiculate, margins entire. Inflorescences terminal, paniclelike or cymelike, not pedunculate. Pedicels absent or present. Flowers bisexual, 3-10 per ocreate fascicle, bases not stipelike; perianth nonaccrescent, greenish, often tinged white or pink distally, narrowly campanulate, glabrous or occasionally with scattered glands; tepals 3 , distinct, sepaloid, monomorphic; stamens (1-)3[-5]; filaments distinct, free, glabrous; anthers white or yellowish, ovate to elliptic; styles 2(-3), erect, distinct; stigmas capitate. Achenes included or barely exserted, light brown or brown to black, unwinged, unevenly 2-gonous, rarely 3-gonous, glabrous. Seeds: embryo curved. x = 7.
Species 6 (1 in the flora): alpine, arctic, and circumpolar, n North America, s South America, n Europe, e Asia.
The five other species of Koenigia are endemic to high mountains of southeastern Asia, primarily the Himalayas (O. Hedberg 1997). K. Haraldson (1978) and L.-P. Ronse Decraene and J. R. Akeroyd (1988) placed Koenigia close to Aconogonon based on morphological data. Preliminary molecular data seem to support that relationship (A. S. Lamb Frye and K. A. Kron 2003).
Hedberg, O. 1997. The genus Koenigia L. emend. Hedberg (Polygonaceae). Bot. J. Linn. Soc. 124: 295-330. Löve, Á. and P. Sarkar. 1957. Chromosomes and relationships of Koenigia islandica. Canad. J. Bot. 35: 507-514.