Pleasantly or unpleasantly odoriferous subshrubs to small trees. Leaves opposite, rarely whorled, palmately trifoliolate, or rarely, unifoliolate (Z. veronicea); lateral leaflets similar to terminal ones but usually smaller. Inflorescence axillary, cymose; bracts persistent (in Victoria). Flowers bisexual; sepals 4, basally fused; petals 4, valvate or imbricate, free, deciduous; stamens 4, free, all fertile, opposite sepals, erect; disc 4-lobed, lobes distinct, gland-like, opposite stamens; carpels 4, more or less free, lacking sterile apex, style terminal on ovary, stigma capitate. Fruit of 1-4 follicles; follicles not transversely ridged, with rounded apices; seeds elliptic, dull, black, released explosively with elastic endocarp.
A genus of 44 species; all but one endemic to eastern Australia, the other to New Caledonia.