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In 2010, the plant fungal pathogen Austropuccinia psidii was detected in Australia. It has since spread rapidly through the eastern states of Australia causing significant population declines in a number of susceptible species. However, there are still a number of potentially vulnerable species that lack the necessary field observations that are needed to accurately gauge the risk Austropuccinia psidii poses to them. Because of this, rapid field assessments of these species have been given the utmost priority. In the spring of 2018 (October) we carried out rapid field assessments for five high priority species. We did not observe active Austropuccinia psidii infection on any of the species at the time of assessment despite the majority of individuals having susceptible new flush. However, we did find evidence of significant previous infection (branch dieback) in the largest Archirhodomyrtus beckleri population we assessed. Therefore, to confirm our observations, it is necessary to re-assess this population when environmental conditions are more favourable for infection to occur in order.
Many aspects of the biology of Genoplesium baueri R.Br. (Orchidaceae) an endangered terrestrial orchid endemic to New South Wales, Australia, remain unknown. In this study observations were made on (1) plant morphology; (2) the biology of the fruit and seeds; (3) the biology of the plant tuber and the spatial patterning of emergent plants ; (4) the morphology of the pollen and the identity of pollen vectors and (5) to develop a preliminary description of the lifecycle of the orchid, by carrying out annual surveys of two key Genoplesium baueri populations in northern Sydney, for a 12-year period and collecting data on fruits, tubers and pollinators opportunistically. Individual plants cannot be tracked from year to year. We observed that each emergent plant produces a tubular leaf and an inflorescence of 1-15 non-resupinate flowers. Fruit capsules contained numerous tiny seeds, which were slightly larger than seeds of a closely related species, Corunastylis filiformis. The papillose surface of mature tubers of Genoplesium baueri differed greatly from the smooth, spherical tubers of Corunastylis fimbriata and is likely to be the site of orchid mycorrhizae. The occurrence of clumps of closely-packed, variously-sized tubers, each subtending single Genoplesium baueri plants, warrants investigation as development by vegetative increase at the tuber level provides one of several possible explanations. The morphology of the pollinarium and evidence of Chloropid fly-mediated pollination was observed. Our better understanding of the natural history and biology of Genoplesium baueri will contribute to orchid systematics and help inform management decisions regarding this species to ensure its persistence into the future.
Genoplesium baueri R.Br. (family Orchidaceae), an endangered terrestrial orchid species endemic to the Sydney Basin, New South Wales, Australia, is known from 13 populations but little is known about its population demographics. To assess the emergent population size, plant size and reproductive output of two key northern Sydney populations, at Ku-ring-gai Chase National Park (KCNP) and Ku-ring-gai Wildflower Garden (KWG), and how these fluctuate through time, intensive field surveys of these populations were carried out over a ten-year period (2009-18). Plants emerged at both sites in every year with a total of 1,249 plant counts made over the 10-year period. From this, we estimate that a total of approximately 500 perennial individuals may exist across both populations, more than previously thought. Although emergent population size did not differ between populations, we found significant differences between the populations in the other measures. The KWG population had taller plants that produced more flowers per plant than the KCNP population, while the plants in the KCNP population had more pollinated flowers and fruit per plant. All of these measures significantly fluctuated through time. This 10-year study has shown that the resilience of key Genoplesium baueri populations is greater than previously thought. However, it has also shown the boom-and-bust nature of emergence, flowering and fruit set in this species, which has highlighted the need for multiyear intensive studies when assessing likely persistence of endangered terrestrial orchid species.
