Aggregated flowering phenologies among three sympatric legumes – The degree of non-randomness and the effect of overlap on fruit set

The flowering phenologies of three sympatric legumes, Dillwynia hispida Lindley, D. uncinata (Turcz.)J.Black and Pultenaea densifolia F.Muell. (Fabaceae), were measured over a three-year period in a semi-arid ecosystem. Each species produced a single flowering episode per year which lasted about 15 weeks and which overlapped considerably with those of the remaining two species. A comparison of the actual flowering schedules over two years with those generated from Monte Carlo simulations showed that the flowering schedules of the three species were significantly clumped. Fruit-to-flower ratios on D. hispida plants were calculated over two flowering periods and these values were correlated with conspecific and heterospecific flower abundances to determine whether the extent of overlap in flowering schedules was associated with elevated or depressed levels of fruit set. Partial correlations between heterospecific floral densities and fruit-to-flower ratios were usually positive, indicating a possible selective advantage favouring these convergent flowering schedules.