Cystostemon Balf.F.

Canescent herbs or subshrubs, setose-hispid with simple hairs. Leaves alternate. Flowers pedicellate in terminal scorpioid cymes or panicles of cymes; bracts small, the lowest leafy. Calyx divided almost to the base into 5 ± non-accrescent linear-ovate lobes. Corolla mauve, blue or green, campanulate, broadened above the insertion of the stamens, widened and naked at the throat; lobes 5, usually much longer than the tube, ovate, acuminate, imbricate, spreading and revolute after flowering. Stamens 5, inserted about the middle or near base of tube; filaments short, linear, narrowly ellipsoid or round, sometimes inflated, with a basal triangular or oblong appendage, sometimes reduced or represented by thickened ciliate ridges; anthers linear, with elongate aristate terminal thong-shaped appendages longer than the anther-thecae and coherent along their margins, not twisted. Ovary 4-lobed; style gynobasic, filiform; stigma capitate. Nutlets 1–4, 3-angled or pyramidal, erect, acute, angular, verrucose with basal areole, dorsally keeled. Seed straight; embryo straight with thick ovate plano-convex cotyledons; radicle superior.