Open Access

Stephen A. J. Bell

• A rare flowering event in a stand of Acacia pendula (Weeping Myall) (family Fabaceae, Mimosoideae) from the Hunter Valley of New South Wales is documented. This species flowers poorly in the region and (with the exception of horticultural specimens) has not been observed to fruit and develop viable seed for over a decade. One stand of this threatened Hunter Valley population of Acacia pendula was monitored over a seven month period (January to July 2018) to investigate this poor reproductive output. Despite copious bud production in January and February, the extent and condition of these, and all subsequent flowers rapidly declined, and none progressed to fruit. Primary reasons for reproductive failure were postulated to be a combination of mass desiccation of capitula following extended dry conditions, infestation by native flower- and phyllode-galling midges and thrips (Asphondylia sp., Dasineura glomerata, Kladothrips rugosus), fungal galls (Uromycladium sp.), caterpillars (Ochrogaster lunifer), and mistletoe (Amyema quandang). Collectively, these stressors appear to be eliminating seed production from the study population; survival is maintained only by the copious root-suckering observed around most plants, particularly after the pressure from stock grazing (cattle, sheep) has been removed. The age of trees studied, based on measures of girth and comparison with growth rates reported for other semi-arid Acacia, was inferred to be between 50 and 150 years. The level of Amyema quandang (mistletoe) infestation on Acacia trees was independent of tree size, and there was no evidence to suggest that mistletoe density alone influenced flowering progress. Consequences of these observations on future management of Acacia pendula in the Hunter Valley are briefly discussed.