Penthorum comes from the Greek words pente, meaning "five" and horos. "a mark"; from the flowers arrangement in five parts. Sedoides comes from the word meaning "like Sedoides" - the flowers of the two taxa being similar.

Prefers the low, wet soils of marshes, lakeshores and ponds, wet prairies and alluvium. Small, yellow-green flowers (petals normally absent) with finely toothed lanceolate leaves. Grows from 1 to 3 feet tall.

The Meskwaki made a cough syrup from the seeds of P. sedoides.

Edible Uses: Leaves - cooked. Used as a potherb.

Medicinal Uses: A tincture of the plant is somewhat astringent, demulcent, laxative and tonic. The plant is noted for its effectiveness in treating catarrhal problems of many kinds and has also been used successfully in treating diarrhoea, haemorrhoids and infantile cholera.

The seeds have been used in making cough syrups.

Herbal Uses: Unknown