Clarkia is a genus within the flowering plant family Onagraceae. Over 40 species are currently classified in Clarkia; almost all are native to western North America, though one species (Clarkia tenella) is native to South America. Clarkias are typically annual plants, growing to a height of less than 1.5 metres. Their leaves are small and simple, from 1 to 10 cm in length depending on the species. Their flowers have four sepals and four petals. The genus was named in honour of the explorer Captain William Clark. The Royal Navy had a warship called HMS Clarkia, a flower class corvette.