Acanthaceae- Gamopetalae  

Mostly herbs, shrubs; leaves opposite decussate, exstipulate, inflorescence cymose, flowers bracteate, bracteolate, zygomorphic, hermaphrodite, hypogynous; calyx five or 4 gamosepalous, corolla pentapartite, gamopetalous, often bilipped; stamens 4 to 2 didynamous, polyandrous, epipetalous; carpels two, syncarpous, ovary superior, axile placentation, style simple, stigma bilobed; fruit loculicidal capsule, seeds non-endospermic with jaculators.