Commonly known as loosestrife (a name they share with Lysimachia, which are not closely related), they are among 32 genera of the family Lythraceae.

Typically they have square stems, narrow stalkless leaves, and spikes of star-shaped flowers in shades of purple, pink and white.

They are especially associated with boggy areas, river banks and ponds, though in cultivation they often tolerate drier conditions.

The genus Lythrum is listed as a noxious weed in Michigan, North Carolina, and Wisconsin.

[9] So far the oldest evidence of Lythrum is fossil pollen from the early Campanian, 82-81 Ma of Wyoming.