Category Archives: News

Spring is here!

Pond in Rymill Park. Photo: B. Baldock.

Lengthening days, bursts of warmer weather – it must be spring. And with it, flower buds of terrestrial plants that have been surreptitiously developing over winter may suddenly burst into a great show of reproductive activity. But also, perhaps not as obvious, and often poorly appreciated, is the frantic activity in freshwater creeks, ponds and water storages in preparation for the drought of coming summer.

We are fortunate in the State Herbarium of South Australia that we have enthusiastic volunteers who not only help greatly in the day-to-day activities of the herbarium, but keep an eye on changing natural events and bring in plants that appear unusual or noteworthy. Recently one of our volunteers brought a sample of green “slime” for us to investigate. It was wrapped around the minute roots of some floating duckweed blown to the edge of a nearby city park pond.

Under the microscope a whole ecosystem of plants and animals was revealed – something more remarkable than the term “slime” implies. The basis of this ecosystem was a striking green alga – Oedogonium. This had strange swellings, some green, some reddish, along the lines of green cells that make up the unbranched threads or filaments of its plant body or thallus.

Oedogonium algae filaments with pine pollen (top image). Photos: B. Baldock.

Interspersed among the filaments were pine pollen grains that had dropped into the pond. These looked like Mickey Mouse hats, hence they were easily identifiable. There were also many colourless, single-celled animals going about their business, mainly filtering out single-celled algae or other animals smaller than themselves.

The filaments also acted as the base for minute threads of innocuous, colourless sulfur-bacteria less than 1 millionth of a metre (1 μm) in diameter. These could be identified, because they contained minute droplets of sulfur that caught the light brilliantly under the highest magnification of our microscopes.

Excitingly, the Oedogonium was reproducing. Swollen cells were acting as eggs (oogonia), and some had tiny attachments – dwarf “males” (or antheridia) – that were fertilizing the oogonia (males can be produced by neighbouring filaments or the same filament). Following fertilisation, red-brown, tough-walled zygotes had formed, ready to germinate into a new filament if conditions were right, or to sit dormant in the dried mud of waterways until the coming rains next season.

Oedogonium algae filaments with sulfur bacteria, oogonium (egg) and antheridium (male). Photos: B. Baldock.

It’s a pity that algal growth in our waterways such as that described above is denigrated. We are conditioned into thinking water bodies should be clear and blue, a state generally signalling they are sterile and lack vibrant, living ecosystems.

And, we rightly fear the appearance of the grey-green scum of toxic, blue-green “algae” that may form in waterways towards the end of summer. But, to be correct, “blue-greens” are bacteria, not true algae. This bacterium blooms at the boundary between an upper, warm, brightly lit layer and a nutrient-rich, cooler bottom layer that forms in still, non-flowing bodies of water. In cities, the nutrients generally come from wastewater run-off, including garden fertilizer and domestic pet excrement.

As a response to blooms of organisms in freshwater we seasonally often add our own toxins such as copper salts and hydrogen peroxide to kill them, wrecking benign living aquatic communities that may have helped in past times to obviate the threat of these blue-greens, by denying them excessive nutrients and establishing broader and more stable food-pyramids.

I hope you agree with me that green ”slime” can be more interesting than its name suggests. And perhaps you might appreciate it, understand its complexities and learn to live with it rather than try to obliterate it.

Further information

  • Entwisle, T.J., Sonneman, J.A. & Lewis, S.L. (1997). Freshwater algae in Australia. (Sydney : Sainty & Associates). – The book is being converted to a website, part of which is already available online.
  • CSIRO (2021). What are blue-green algae. [accessed: September 6, 2021].

Written by Hon. Research Associate Bob Baldock.

Research news: Ptilotus in arid Australia

A new paper on the evolution of the genus Ptilotus in arid Australia was published by Tim Hammer, who is currently working as a post-doc at the State Herbarium of South Australia and The University of Adelaide with Chief Botanist, Prof. Michelle Waycott.

T.A. Hammer, M.Renton, L. Mucina & K.R. Thiele. Arid Australia as a source of plant diversity: the origin and climatic evolution of Ptilotus (Amaranthaceae). Australian Systematic Botany 34: 570-586.

Ptilotus rotundifolius, Murchison region, WA. Photo: T.A. Hammer.

The authors tested the chronological and geographic origins of the mostly arid Australian genus Ptilotus (Amaranthaceae) and its close relatives (i.e. the ‘aervoids’) by reconstructing a dated phylogeny with near comprehensive sampling for Ptilotus and estimating ancestral geographic ranges. Their analyses support the hypothesis that a pre-adaptation to aridity and early arrival in an aridifying Australia were integral to the success of Ptilotus, and that the Eremaean zone has been a source of biodiversity in the genus and for independent radiations into neighbouring climatic zones.

Tim now works on Hibbertia (Dilleniaceae), one of the most species-rich genera in Australia, in collaboration with State Herbarium Honorary Research Associate Hellmut Toelken and colleagues from South Australia and interstate.

Research news: fungi papers published

During the last week, two papers were published by State Herbarium of South Australia‘s mycologist, Dr Teresa Lebel, and co-authors in the online version of the journal Mycologia:

Agaricus xanthodermus, p = pileus; s = stipe; a = annulus. Photo: A.-G. Boxshall.

(1) A.-G. Boxshall, J.L. Birch, T. Lebel, M.R.E. Symonds & D.L. Callahan (2021). A field-based investigation of simple phenol variation in Australian Agaricus xanthodermus. Mycologia (Publisher’s website).

Agaricus xanthodermus (yellow stainer) and other species of the yellow-staining Agaricus sect. Xanthodermatei are responsible for mushroom-related poisoning cases that require treatment. However, longstanding anecdotal evidence indicates that this species appears to exhibit considerable variation in toxicity, resulting in gastrointestinal irritation of varying severity in most cases. During her MSc research, the first author quantified the amount of phenol, hydroquinone and catechol in mushrooms and investigated their levels in different fungal structures, different developmental stages and on different nutritional substrates.

(2) J.I. de la Fuente, J.P. Pinzón, L. Guzmán-Dávalos, M.O. Uitzil-Colli, D. Gohar, T. Lebel, M. Bahram & J. García-Jiménez (2021). Revision of the genus Restingomyces, including two new species from Mexico. Mycologia (Publisher’s website).

The paper is the result of a long-standing collaboration to document the truffle diversity in American tropical regions. After a series of field surveys in southeastern Mexico, two new species in the phalloid genus Restingomyces (Trappeaceae, Phallales) were discovered. The authors describe them based on morphology and phylogenetic analyses of molecular data. Restingomyces guzmanianus and R. yaaxtax occur in medium-statured tropical dry forests. The original diagnosis of the genus Restingomyces is emended to include these novel species.

The new South American truffle Restingomyces guzmanianus, A = truffle cut in half, B = outside. Photo: J.I. de la Fuente et al.

New journal article: August 2021 (2)

The State Herbarium of South Australia published one short communication in Vol. 35 of its journal Swainsona online, today, 18 Aug. 2021.

xPhelodia tutelata. Illustration by F.J. Bradley, first published in Rogers (1906).

J. Kellermann & A. Monro, ×Phelodia, a new nothogenus in Australia Orchidaceae. (0.1mb PDF)

The recently published ×Glossadenia tutelata is a hybrid between the well-known orchids Glossodia major and Caladenia deformis. However, the latter species has now been transferred to another genus, Pheladenia. As the International Code of Nomenclature (ICN) prescribes that the names of hybrid genera consist of parts of the names of the parent genera, the hybrid genus ×Glossadenia needs to change its name, when the Caladenia deformis is accepted as Pheladenia deformis. The authors publish the new hybrid genus xPhelodia and the hybrid species xPhelodia tutelata to satisfy the requirements of the ICN.

To access content of all volumes of Swainsona and the Journal of the Adelaide Botanic Gardens since Vol. 1 (1976), please visit the journal’s web-site at flora.sa.gov.au/swainsona or the Swainsona back-up site.