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Floral morphology of Eucalyptus leucoxylon (Myrtaceae) facilitates pollination by lorikeet (Aves: Psittacidae) tongues.

journal contribution
posted on 10.02.2021, 23:25 by Joseph Zilko, Susan HoebeeSusan Hoebee, Trevor J Edwards
© CSIRO 2017. Bird pollination is particularly common and widespread in the southern regions of Australia. Despite some eucalypts being heavily frequented by birds, they are usually considered to have a generalist pollination system because of their apparently unspecialised floral morphology. A few species possess protandrous anthers that dehisce within a tightly furled dome of filaments. We hypothesised that this facilitates pollen transport via the brush tongues of lorikeets. Using Eucalyptus leucoxylon F.Muell. and five captive rainbow lorikeets (Trichoglossus hematodus) as a model, we demonstrated that lorikeets remove significant quantities of pollen from flowers with inflexed filaments in a short time (30min), compared with bagged control flowers (Mann-Whitney U test, Z≤165.4, d.f.≤29, P≤0.008). Some of this pollen is deposited on stigmas by the tongue, which is the organ that most regularly and reliably contacts stigmas. The mean number of pollen grains deposited on stigmas by each bird was as high as 121.2. Adhesive tape contacted by the tongue during foraging removed up to 2104 pollen grains, which was significantly greater than for uncontacted control tape (Mann-Whitney U test, Z≤110, d.f.≤21, P<0.001). Scanning electron micrograph imaging of a lorikeet tongue showed many pollen grains that had been transferred onto its keratin papillae, which is likely to have contributed to high carryover rates by retaining pollen for a substantial amount of time. Minimal pollen is available for generalist pollination once the filaments unfurl. It appears highly unlikely that insects are able to access pollen from these male-phase flowers and inflexed filaments may therefore fulfil an exclusionary role.


We thank Moonlit Sanctuary Wildlife Conservation Park for kindly allowing us to work with their captive lorikeets for data collection. This research was also supported in part by an honours student scholarship provided by Biosis Pty Ltd. We also thank Peter Lock from the LIMS Bioimaging Facility for providing access to the electron microscope and assistance with imaging. We are grateful for the valuable feedback provided by Andrew Bennett and John Morgan on early versions of the manuscript, in addition to the valuable insights provided by three reviewers. This research was undertaken with approval from the La Trobe University Animal Ethics Committee (Approval no: AEC15-80).


Publication Date



Australian Journal of Botany






7p. (p. 368-374)


CSIRO Publishing



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