Eucalyptus gardneri, a Western Australian species, exhibited pollen-limited seed set during October 1998 in the Monarto re-vegetation woodlands. Flowers pollinated with additional cross-pollen (56%) matured significantly more fruit than both self-pollen (21%) and natural pollination (30%). Flowers treated with cross-pollen (median=4) also set more seeds per fruit than both self-pollinated (2) and control flowers (2). Low seed production in naturally pollinated flower suggests that flowers were either not receiving adequate quantities of pollen, or if pollen quantities were sufficient then the pollen was predominantly self-pollen.

Honeyeater visitation to E. gardneri during October was high (19 visits/hour) and was greatest in the morning when pollen accumulation on flowers was highest. Honeyeaters preferentially foraged in the upper canopies of both E. gardneri and E. platypus (observed in December 1998), although bout lengths did not vary significantly between canopy heights. Preference for upper parts of trees was not explained by the distribution of flowers or nectar production, which ranged from 0.44 to 3.17mg sucrose/day/flower in the upper canopy and 0.33 to 3.65mg sucrose/day/flower in the lower canopy.

Pollen-limitation in E. gardneri appears to be caused by low access to pollen, rather than poor pollinator service. Conspecifics are planted too far apart to disperse pollen effectively. Variation in the response to additional cross-pollination suggests that both the quality of pollen and also the timing of pollination will affect the ability of flowers to set seed.