Floral micromorphology of bird-pollinated carnivorous Utricularia

Most bladderworts (genera Pinguicula, Genlisea, Utricularia, Lentibulariaceae) are pollinated by insects. Bird pollination is rare and has probably evolved independently three times in this family.

In Western Australia, the Western spinebill, Acanthorhynchus superciliosus, visits flowers of Utricularia menziesii. Płachno et al. study the micromorphology of U. menziesii flowers to assess traits that are likely linked to its pollination strategy. The flowers fulfil many criteria that characterise bird-pollination: red colour, a large, tough nectary spur that can withstand contact with a hard beak, lack of visual nectar guides and fragrance. The hexose-dominant nectar that was detected in flowers of U. menziesii is common in plants pollinated by passerine perching birds.