Like all Nivenia species, Stokoe’s bush iris is interesting because it is one of the few plants in the iris family that exhibits heterostyly. Nivenia species produce two different types of flowers; one has a long style and short stamens, the other has long stamens and a short style (5) (6). This prevents the anthers and stigmas in each flower from coming into contact with each other, and prevents self-pollination. The different lengths of stamens and styles are adapted for pollination by different pollinating insects, or different body parts of the same insect. This encourages pollination between the two different flower forms. Cross-pollination ensures the offspring are genetically unique from the parents and thus maintains genetic diversity; an advantage in a changing environment (7).
The stunning flowers of Stokoe’s bush iris, which bloom from February to March (2), are pollinated by visiting insects, including flies of the family Nemestriniidae and long-tongued bees belonging to the family Anthophorideae (1).