Erect or decumbent undershrub, branches herbaceous; leaves opposite, ovate, elliptic or oblong, acute or subacute at apex, narrowed at the base into a short petiole, stipules narrow, multifid; flowers clustered in terminal corymbose cyme, bisexual, actinomorphic, pentamerous; calyx tubular with 5 lobes at apex; corolla pink, pale purple, white or in many colours; petals 5, clawed, limbs spreading; stamens 4-6, epipetalous, included at the troat of corolla tube; stamens-5, epipetalous, anthers subsessile; ovary 2-celled, syncarpous, ovules many, style slender, stigma bifid; capsules ovoid, membranous; seeds numerous, black, minute.