Habit: Herbs or shrubs (rarely woody vines or trees), stems 4-angled
Leaves: opposite (rarely whorled), simple (pinnate), estipulate, punctate and aromatic
Inflorescence: axillary cymes or verticils, sometimes racemiform, paniculiform or headlike, or solitary
Petals: 5, connate, bilabiate and often only 4 lobed
Stamens: 2 or 4, distinct, epipetalous
Ovary: 2 carpels, connate, superior, 4 lobed or divided into 4 locules with 1 basal ovule per locule; style 1, gynobasic, 2 lobed near apex