Gypsywort is a medium to short perennial growing to about 1m. With its flowers in whorls, square stem and opposite leaves it looks rather like a mint with strongly notched leaves, however, it is different in being odourless and having two not four stamens per flower. The flowers, which are present from June to September, are white dotted with purple.
Gypsywort is a native perennial that will grow in a wide range of wet soils. It is found growing on the banks of rivers, streams, lakes and ditches and in fens. It readily colonises exposed mud and once established from seed spreads by means of rhizomes.
Grows readily from seed sown at any time of the year.