Reproductive ecology and breeding system of Lomatia silaifolia (Proteaceae) following a fire

Abstract

Lomatia silaifolia (Smith) R.Br. (Proteaceae) is a common shrub in southeastern Australian bushland that generally flowers only once after each fire. However, little is known of the details of this post-fire flowering. Lomatia silaifolia has flowers well-spaced along its conflorescence axis, unlike many other Proteaceae species, thus allowing close examination of the influence of flower position, mate choice and flowering sequence on fruit production. We examined breeding system, flowering phenology and spatial patterns of fruit set in the species, after a fire in September 1992 at Bulli Tops, New South Wales. Flowering occurred in December–January, but only in the first and second summers after the fire. The species is partially self-compatible: only 25% of self-pollinated conflorescences initiated fruits compared with 100% of cross-pollinated conflorescences. Fewer flowers initiated fruits after hand self-pollination (3.0%) than after cross-pollination (35.4%). Self-pollinated flowers produced fewer viable seeds (22.2% viable) than cross-pollinated flowers (62.9% viable). Pollen tubes were found in 72% of the self-pollinated flowers examined, suggesting that there is no early stylar self-incompatibility in the species. There was a high level of herbivory on flowering and fruiting branches, with 69% of unbagged branches completely destroyed. This may significantly affect recruitment in the species, given the limited opportunities for reproduction in the post-fire environment. In this study, fruits were evenly distributed along the conflorescence axis unlike some other species in the Proteaceae with more compressed, spike-like flowering structures where fruits are typically concentrated in some parts of the conflorescence axis (e.g. Telopea and some Banksia spp.). No bird visitors to flowers were observed, but a variety of insect visitors were identified.