Non-flying mammal pollination in Massonia grandiflora

Abstract

Pollination by small non-flying mammals occurs in Africa, Australia, Asia and the Neotropics. One hotspot is in the winter rainfall zone of the Cape Floral Region of South Africa. This phenomenon is known for a handful of plant lineages, of which one comprises geoflorous monocots including the tribe Hyacintheae of the Asparagaceae. Small mammal pollination has been documented for four members of the Hyacintheae. A further representative of this taxon, Massonia grandiflora, is hypothesized to be pollinated by small mammals as it shares floral characters with other plants adapted to small mammal pollinators. The study aims at the identification of the pollinators and the characterisation of the floral features of M. grandiflora as well as to experimentally test whether the plants’ nectar scent is an attractant to the flower visitors. With direct observations and video monitoring, we demonstrate the fitting between the head of elephant-shrews and rodents and the bowl-shaped flowers with protruding stigmas and styles as well as pollen transfer from the plants’ anthers on the animals’ body parts that made contact with the stigma. We experimentally show the transfer of pollen surrogates by elephant-shrews and rodents from the anthers via the animals’ fur onto the stigmas of conspecific flowers. Pollen loads on the animals’ snout and in their faeces represent indirect evidence for flower visits. Insects and birds were not observed as nectar consumers. Choice tests revealed that mice and elephant-shrews are attracted by nectar scent. We conclude that the fragrant nectar attracts mice and elephant-shrews as pollinators, whereas its bitterness and viscosity as well as the flowers’ visual crypsis might filter out insects (and birds) as less effective pollinators.