The family mainly comprises herbs and shrubs, often climbing, while trees are rare. The leaves are usually decussate. The flowers are bilabiate, the ovary is bilocular. The fruit is a loculicidal beaked capsule opening with 2 valves. The funicle develops a hook-like process which aids in the expulsion of the seeds. The seed coat often has a slimy epidermis. Seeds are usually without endosperm, but with a large embryo.