Genus of mostly aquatic, with some terrestrial species commonly called starwort. There are around 63 described plants and these are hardy, herbaceous perennials. This genus evolved from boggy, marshy environments in Europe, Asia and North America. Foliage is linear to rounded spoon-shaped and tiny, star-shaped flowers are produced from all leaves, even those which become partially translucent when deeply submerged. Species in this genus make good pond plants for oxygenating water.