Reproductive biology of the endangered artesian spring endemic forb Eriocaulon carsonii (Eriocaulaceae) in arid south Australia

Background/Question/Methods

This study examined floral biology, seed germination, seed dormancy, and seed bank dynamics of the nationally endangered perennial forb Eriocaulon carsonii that is endemic to artesian springs in central and eastern Australia. An understanding of intrinsic and extrinsic factors limiting seed set, seed survival and germinability is important for managing the conservation of this rare and endangered wetland plant species that occurs on small isolated springs which are subject to significant temporal and spatial variations in water flow.

Results/Conclusions

Plants grown ex situ had similar seed set when artificially self-pollinated or outcrossed. A degree of spatial and temporal separation of female and male flowers in inflorescences may reduce self pollination.  Seeds were found to germinate readily without special pre-treatments at temperatures between 21°C and 30°C, both when submerged in water and when exposed to air on a damp substrate. However, little or no seed germinated in the dark or in high (38/33°C; day/night) or low (14/11°C) temperatures. While springs with extant healthy populations had large numbers of seed in soil seed banks, seed which was buried in the soils of springs were short lived, probably due to the inability of seed to remain viable when submerged in water for long periods at high temperatures. In contrast, seed stored dry at room temperature is relatively long-lived as is seed stored in water in the dark at 30/27°C.  The apparent lack of a persistent seed bank in the field indicates the importance of managing springs to maintain healthy populations of mature E. carsonii individuals.