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Entwisle T.J.,Royal Botanic Gardens Victoria | Johnston E.T.,Ohio University | Lam D.W.,Ohio University | Stewart S.A.,Ohio University | Vis M.L.,Ohio University
Journal of Phycology | Year: 2016

The informal “Australasica Group” was established in 2009 to include several Australasian endemic Batrachospermum species, a few species of the cosmopolitan Batrachospermum section Setacea, and the South American endemic Petrohua bernabei. Although useful for communication purposes, no formal taxonomic designation was proposed due to weakly supported basal nodes. The present research took a two-pronged approach of adding more taxa (29 additional specimens) as well as more sequence data (LSU, cox1, psaA, and psbA markers added to rbcL data) to provide better resolution. The resulting tree showed improved statistical support values (Bayesian posterior probability and maximum likelihood bootstrap) for most nodes providing a framework for taxonomic revision. Based on our well-resolved phylogeny, a new genus, Nocturama, is proposed for a clade of Batrachospermum antipodites specimens. The circumscription of Nothocladus is expanded to include Batrachospermum section Setacea and four additional sections composed of at least 10 species, mostly from Australia and New Zealand. One new species added to the data set, N. diatyches, did not form a clade with the other species of section Setaceus, where it was classified previously, rendering that section paraphyletic. To resolve this, N. diatyches and the morphologically similar species N. latericius are included with N. theaquus, in the new section Theaquus within Nothocladus s. lat. A specimen from Australia unaligned to these clades was sister to the Australia–New Zealand genus Psilosiphon and the cosmopolitan B. cayennense, but lacked statistical support. This specimen has the gross morphology of Batrachospermum s. lat. and is here provisionally assigned to that genus, as B. serendipidum sp. nov. © 2016 Phycological Society of America Source

Cantrill D.J.,Royal Botanic Gardens Victoria | Ashworth A.C.,North Dakota State University | Lewis A.R.,North Dakota State University
Grana | Year: 2016

The paucity of late Paleogene and Neogene floras from Antarctica limits our ability to understand the interplay between Antarctic climate evolution and the impact that glaciation had on the vegetation, in particular, how the vegetation changed from temperate Eocene forests, to today’s sparse vegetation. Fluvial and lacustrine strata deposited in a wet-based glacial sequence (Friis Hills, McMurdo Dry Valley sector, Transantarctic Mountains) have yielded abundant megaspores. These strata are early Miocene based on correlation with a volcanic ash dated at 19.76 ± 0.11 Ma. The megaspores are up to 736 µm in diameter with well-developed wing-like laesurae and equatorial zona. The morphology is consistent with extant Isoetes, and demonstrates the presence of Lycopsida and the Isoetaceae within Antarctic Miocene floras. Today, Isoetes is widespread from the Tropics to the Arctic such as Greenland (I. echinospora, I. lacustris) and from marginal marine (I. ekmanii) to high altitudinal environments (I. lechleri), though commonly associated with lacustrine or aquatic environments. The fossil spores occur in fluvial and lacustrine beds, suggesting the parent plants were aquatics. The occurrence together with mosses and Nothofagus leaves points to persistent vegetation in the early Miocene of Antarctica. © 2016 Collegium Palynologicum Scandinavicum Source

Reiter N.H.,RMIT University | Reiter N.H.,CNR Institute of Neuroscience | Walsh N.G.,Royal Botanic Gardens Victoria | Lawrie A.C.,RMIT University
Australian Journal of Botany | Year: 2015

Borya mirabilis Churchill (Boryaceae, Asparagales) is a herbaceous perennial and one of Australia's most endangered plants. Only one population of four colonies remains, on a rock ledge in the Grampians (Gariwerd) National Park in Victoria, Australia. The reasons why B. mirabilis flowers freely but does not set seed were investigated. Borya mirabilis had a greater proportion of floral abnormalities than other, fertile Borya species. The pollen was often mis-shapen, with≤1% pollen tube formation, but the ovules showed no structural dissimilarity from other, fertile Borya species. The flowers offered a nectar reward and many insects visited the pollen-bearing flowers in the field. Artificial cross-pollination resulted in the first recorded seed for this species. Borya mirabilis has ∼66 chromosomes, relative to the diploid number of ∼26 in Borya constricta Churchill, strongly suggesting that B. mirabilis is polyploid. Only 4-7% genetic diversity was found within the remaining B. mirabilis field population using 25/60 RAPD primers that showed heterogeneity. An ex-situ nursery collection was found not to contain all genotypes. Recommendations for the conservation of B. mirabilis include capturing all the known genetic diversity in cloned plants in preference over further attempts to produce seed. © CSIRO 2015. Source

McDougall K.L.,Office of Environment and Heritage | Walsh N.G.,Royal Botanic Gardens Victoria | Wright G.T.,Office of Environment and Heritage
Australian Journal of Botany | Year: 2015

The vegetation of fire-prone landscapes is influenced by the frequency, severity, seasonality, return interval and stochastic patterning of fire as well as the responses of its component species. An expected increase in fire frequency and severity in association with global warming may result in compositional changes within, and spatial reorganisation of, plant communities; indeed, some plant communities may even face extinction. Vegetation dominated by fire-sensitive species may be most vulnerable to change in fire frequency. A landscape-scale fire in Kosciuszko National Park in 2003 provided an opportunity to compare recovery in vegetation dominated by resprouters and fire-sensitive, obligate seeders. We hypothesised that if plant assemblages had failed to recover after 10 years in terms of species richness and cover they would have been dominated by seeder species pre-fire. After 10 years, two of the six vegetation types investigated had recovered and these were indeed dominated by resprouter species. Two groundwater-dependent vegetation types (one resprouter-dominated and one dominated by fire-sensitive species) were close to recovery. However, the other two types, non-groundwater-dependent shrublands dominated by both seeder and resprouter species, were still far from recovery at that time, with shrub cover reduced and grass cover increased. The likelihood of recovery after 10 years therefore does not appear to be solely a consequence of the regeneration strategies of the dominant species. Post-fire environmental factors (e.g. grazing, disease, climate) may be just as important as regeneration strategies in determining recovery time. Because not all vegetation had recovered after 10 years, prediction of minimum tolerable fire intervals at a landscape scale is impossible at this time. Future fire management needs to be adaptive, taking into account post-fire influences, rather than prescriptive.Journal compilation © CSIRO 2015. Source

Entwisle T.J.,Royal Botanic Gardens Victoria
Acta Horticulturae | Year: 2015

Since 1788, Australia has persisted with four European seasons that make no sense in much of the country. Australians may like them for historical or cultural reasons, or because they are they are (apparently) the same throughout the world, but they tell us nothing, and reflect less, of our natural environment. I argue for a rejection of these seasons and the adoption of a system that brings us more in tune with our plants and animals; a system to help us to notice and respond to climate change. I propose a 5- season model for southern Australia, starting with sprinter (August and September), the early Australian spring. That is when the bushland and our gardens burst into flower. It is also when that quintessential Australian plant, the wattle (Acacia), is in peak flowering across Australia. Next is sprummer (October and November), the changeable season, bringing a second wave of flowering. My proposed summer (December to March) is four months long, extending into March. Autumn (April and May) reflects the brief colouring of leaves on mostly exotic trees, but also peak fungal fruiting. Winter (June and July) is for that short burst of cold weather. I'm not the first to suggest an alternative way to divide up the year. Australia's Aboriginal communities have watched the world around them over tens of thousands of years, and come up with two to thirteen seasons to suit their local area. I'm also not the first recent immigrant to suggest we need a change. Any system covering such a large area will be a compromise, and I have based mine mostly on what plants do. Whether my new seasons are adopted or not, I hope they encourage people to take better notice the natural world around us and how it changes. Source

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