Extending the olive branch

In one of our previous posts I spoke about our senescent tree collection and how we are working to ensure their survival at our historic sites Just over a year ago we started a project to ensure the genetic survival of the Elizabeth Farm European olive tree (Olea europaea), which is believed to be Australia’s oldest living cultivated olive tree.

The goal of the project was to propagate vegetatively (that is from cuttings) to get replacement plants that would then be well-established as backup plants ready in case of a rapid decline/death of the parent plant. We were also approached by a local council and a memorial to supply cuttings from our historically significant olive as a symbol of peace.

With only limited glasshouse facilities and propagation equipment, we had achieved little success previously, so we asked our good friends at the Australian Botanic Garden, Mount Annan (ABGMA) to lend us their experienced hand with the project. John Siemon, curator manager at Mount Annan was kind enough to lend us his staff and facilities to grow our new (but old) olives to a stage where we could take over their care.

Feburary 2017: Mark Viler, nursery manager at ABGMA meets our MHNSW horticulturists and one of our garden volunteers at Elizabeth Farm to collect the propagation material from the olive. They managed to take around 100 cuttings which Mark took back to ABGMA with him to place in growing media and provide the right simulated conditions to encourage roots to form.

March 2018: It was time for us to collect the new plants! As the MHNSW gardens team and I had never visited the Australian Botanic Garden, our horticultural coordinator organised with John for us to tour the facilities and learn a little about the process the olives went through before the handover. The day of our visit was a little damp and dark but that didn’t stop the team’s excitement for what was ahead of us. John met us with a brief introduction about the site and an insightful background to the amazing things they have been achieving there.

First stop was a tour through the Plant Bank where they have been working very hard to conserve Australia’s native plant species. Inside this building they are researching how plants grow and investigating how to preserve our native species for the future. The plant bank contains thousands of seeds from all over Australia, stored indefinitely to help ensure that we keep our native plant diversity alive and thriving. I highly recommend a visit to see how they are achieving this.

We then met with Mark who took the original cuttings from the olive at Elizabeth Farm to see how our plants had turned out. Mark took us on a tour through the nursery and glasshouses where we were able to see their facilities and most importantly, observe the process the olive cuttings went through to reach their current stage. Initially the olives were placed in a root-inducing potting mix, then placed into a humidity and temperature controlled glasshouse, which encouraged root growth, and reduced any moisture lost through the leaves. Once roots had formed, the rooted cuttings were then transferred in to larger pots and nutrient-rich soil mixture as they matured. As with most plant propagation, there will always be a percentage of plants lost throughout the process, due to a range of factors. Our olives had around a 30% success rate, meaning we had 30 plants survive from the original 100 cuttings. This is a relatively low strike rate but often what happens with very old plants.

Getting to see the vast native plant collection, including a large collection of Grevilleas and Wollemi pines, was very cool. It made me realise that I have so much to learn outside of our very different property plant 'palettes'. This led us to a trolley in the potting shed and from a distance we could tell that they were the olives we had come to collect as they had the distinct blue/grey foliage. The plants were very healthy and well established and a testament to the gardens who had done a fantastic job in getting the plants to this stage.

We were then treated to a tour of the expansive grounds where we got to see the plants and displays, it was great to see how they achieved results and for us to question and learn from each other’s strengths. Coincidentally we learnt of the struggle they have been facing in removing the huge amounts of African olive (Olea europaea ssp. cuspidata) that has overrun a large area of their native bushland.

I want to extend a huge thank you to everyone from Mount Annan who was involved in the growing of our olives and also everyone who showed us such hospitality when we were there, I’m sure our relationship will continue to grow in the future.

Today: Since collecting the plants, Dr Zeny Edwards, (SLM) Governors’ Circle donor and member, worked with us and Ku-ring-gai Council to celebrate UN Observance Day: International Day of the Forest. Countries are encouraged to undertake local, national and international efforts to organise activities involving forests and trees. What better way to celebrate sustainability than to plant an olive tree cutting propagated from the oldest recorded olive tree in Australia, at Elizabeth Farm? The cutting was planted in St Ives Arboretum on 21 March 2018 by Ku-ring-gai Council Deputy Mayor, Cr Callum Clarke. The olive is acknowledged with a plaque featuring John Macarthur’s quote (see below). This planting could be beneficial to us in the future, knowing that we have genetically identical plant material located around Sydney to provide us cuttings again if needed. We are also currently planning to plant a few new trees back at Elizabeth Farm and possibly in the surrounding parkland.

Come and visit the original olive tree, which enabled John Macarthur to claim credit for pioneering the olive in Australia at Elizabeth Farm. You will notice that underneath the tree sits a cut section of one of the main trunks that had to be removed due to internal decay, showing its size and age.

Amongst the plants that I have been so fortunate as to bring out alive is the olive, and I hope as an emblem of Peace its branches and that blessing will spread together and be universally propagated throughout the whole country.

John Macarthur writing to James Chapman, who was the under-secretary to the colonial office. 20 July , 1805. It’s quoted in Ellis’s book John Macarthur p242. Source: Colonial Office Papers, Public Records Office, London, 201/38, 239-40.