Genera 2, species 8 (8 in the flora).
Placement of Limnanthaceae in Brassicales is supported by molecular and chemical data, especially the presence of mustard oils. Traditionally (A. Cronquist 1981), the family has been associated with the Geraniaceae in the Geraniales because of the similarity of habit and floral structure, especially the fruits that separate into mericarps, as do those in Geraniaceae.
Limnanthaceae are endemic to North America. The greatest diversity is in California, where most of the species of Limnanthes occur. Floerkea, with a single species, occurs widely across the continent; it is barely present in the southeastern United States.