The State Herbarium has chosen Eucalyptus camaldulensis Dehnh. (river red gum), as Plant of the Month for February 2016. It is an iconic tree across South Australia and in the Murray River National Park, this month’s Park of the Month.

River red gums at Katarapko Island, Murray River National Park. Photo: Peter Canty.

Eucalyptus camaldulensis has one of the widest natural distributions for an Australian tree, and is one of the most commonly cultivated eucalypts around the world. Accordingly this wide distribution has produced much variation, and seven subspecies are now recognised, E. camaldulensis subsp. camaldulensis occurs along the Murray River.

The habitat of E. camaldulensis is typically along watercourses and floodplains, however the species also occurs on hills in the Mt Lofty Ranges. Its tolerance to flooding is in part due to its massive size and its ability to grow roots quickly and produce adventitious roots on submerged stems. One study has shown that 9 month old cloned plantlets could produce more than 8 km of roots. Its seed floats for some time and is released predominantly during flooding months.

“Spirit of endurance”, Harold Cazneaux well-known photograph of a river red gum near Wilpena Pound, Flinders Ranges. Art Gallery of NSW.

The trees ability to attain massive sizes with hollows makes it an important habitat for many animals (regent parrots, bats, possums, goannas) and insects (49 species have been recorded from a E. camaldulensis forest canopy on the river). Submerged roots and branches are important to many fish like the murray cod. Many intimate fungal associations also exist, one example being the basidiomycetous yeast Cryptococcus gattii. This is released from the tree during flowering and has resulted in the deaths of immune suppressed people (pdf) in Australia and around the world where E. camaldulensis grows, the spores being transported to other countries with the seed.

The age of large trees is difficult to ascertain in part due to the natural hollow formation, some authors indicate ages from 500 to 1000 years. The long history of human use of the tree is still very evident from all the Aboriginal Nations along the river, with many canoe and shield trees found on living and dead trees of considerable age. More recent use has seen the wood used for heavy construction, railway sleepers, furniture and firewood. Honey and a good source of pollen for bees is also significant.

Canoeing under river red gums along Katarapko Creek, Murray River National Park. Photo: Juergen Kellermann.

The name relates to the cultivation of the type specimen at Camaldoli near Naples in Italy in 1832. However study of the type indicated that it was another eucalypt, possibly quite unrelated. An earlier used name, E. rostrata Schltdl., was invalid, while a name given by Mueller, E. longirostris F.Muell. ex Miq., was valid. Because the name E. camaldulensis is so widely used around the world, Brooker & Orchard (2008) applied to conserve the name and select a new holotype. This was successful and a Dean Nicolle collection from Currency Creek was selected. The full discussion of this fascinating typification can be found in a paper by McDonald et al. (2009).

Feel free to contact the State Herbarium’s expert on the eucalypt family Myrtaceae, Martin O’Leary (martin.oleary@sa.gov.au), for specific references or more information.

Further reading can be found at:

• J.Williams & J.Woinarski. (eds). Eucalypt ecology: individuals to ecosystems. Cambridge University Press. 1997.
• http://www.anbg.gov.au/cpbr/WfHC/Eucalyptus-camaldulensis/
• Nicolle, D. (2014). Myrtaceae (partly) (version 1) [10MB PDF]. In: Kellermann, J. (ed.), Flora of South Australia (ed. 5). 102 pp. (State Herbarium of South Australia: Adelaide). flora.sa.gov.au/ed5
• Anon. (2010). River red gum woodlands of watercourses and floodplains. (SA Arid Lands NRM Board: Port Augusta). [560KB pdf factsheet]

Acacia alcockii, habit

This month’s Park of the Month is Coffin Bay National Park on southern Eyre Peninsula. The State Herbarium has chosen Acacia alcockii Maslin & Whibley (Alcock’s wattle) as the Plant of the Month, as the species is endemic to southern Eyre Peninsula. It grows in coastal and near-coastal areas, mainly in sand over limestone. Alcock’s wattle is listed as ‘rare’ for South Australia.

The species was described by Bruce Maslin and David Whibley in 1987. It is a bushy shrub, 2-3 m in height, and can be distinguished from its closest relatives, A. anceps and A. leiophylla, by the combination of racemose inflorescences consisting of small pale yellow globular flower heads, and transverse seeds in the pods (see line drawing from worldwidewattle, below).

The collector: C. Ray Alcock (1921-2015)

The wattle is named after Ray Alcock, one of the State Herbariums most prolific collectors, who died earlier this year. Besides A. alcockii, he is also commemorated in the species name Rumex alcockii Rech.f., now a synonym of R. brownii Campb.

Charles Raymond Alcock (1921–2015) followed his father’s footsteps into the field of agriculture. Ernest Simpson Alcock was an early (1904) graduate of Roseworthy College, where his son was later to study as a scholarship student. Ray’s childhood was spent on the Kybybolite Experimental Farm in the south-east of SA, where his father was employed as a supervisor. From Roseworthy, Ray left to serve in World War II, later with the RAF in Britain, gaining a DFC for his efforts.

Acacia alcockii, phyllodes and pods

Although Ray also gained a diploma in dairy studies from Hawkesbury College and spent his early working in the dairy industry, he turned his attention to plants (and specifically weeds) in the 1950s. Plants and nature conservation became his passion from then until his death, and he became a prolific collector for the State Herbarium, which holds around 12,000 specimens under his name. He joined the Nature Conservation Society of SA in 1964, only 2 years after its formation. He was nominated for membership by then head of the State Herbarium, Dr Hansjörg Eichler.

Most of his earlier plant collections are from Eyre Peninsula, where he was employed by Local and State Government as a Weeds Officer for the Eastern Eyre Peninsula Weeds Board / Lincoln Council and the Department of Agriculture. His collections were certainly not restricted to weeds, and early correspondence with the Herbarium indicates that he found a number of plants not previously recorded for the Eyre Peninsula region. In 1971 he was transferred to the head office of the Agriculture Department in Adelaide, where he was employed as an agronomist with the Weeds Section. He was the Local Government Liaison Officer for some time and latterly specialised in weeds identification and advice with the Pest Plants Commission, building up an extensive herbarium of weed specimens, which has since been transferred to the State Herbarium.

In his retirement he worked with the State Herbarium as a volunteer and collected widely around Australia during his holiday trips. Plants even extended to his hobbies, as he was an avid and talented wood carver.

worldwidewattle.com