Vegetative key to the families

Either: leaves whorled; or leaves opposite and interpetiolar stipules present (Fig. 29). Herbs and woody plants
Leaves whorled, or stipules as large as leaves giving the appearance of 6–8 whorled leaves
Herbs
Stems angular, usually quadrangular, leaves narrow
Leaves in whorls of 3 Lythraceae
Flowers irregular; hypanthium spurred or swollen on one side at the bas Cuphea
Flowers regular; hypanthium without swelling or spur at the base