Dr Peter Weston on 'Gondwanan Plants of the Sydney Region' 25/11/17
Testing the Gondwanan hypothesis: Findings
The evidence suggests that the Gondwanan hypothesis does hold to some extent but that the story is not so simple. The evidence also suggests that dispersal across oceans has played its part in the distribution of our southern plant genera.
So, were Hooker and Darwin both right and wrong?
To sum up: scientific study has supported the Gondwana theory as the origin of some species, while other species arose from individual mutations which were then spread by wind and water. For some species, both processes have played a part.
Westhead Challenger Track 7/10/17
Marilyn Cross & Lesley Waite
On 7th October, 2017, APS ParraHills went to Westhead Ku-Ring-Gai Chase NP for a bushwalk along the Challenger Track which runs from the roadway along the ridgetop until it meets the cliff top, looking out over the mouth of the Hawkesbury River towards Brisbane Water National Park.
The terrain is sandy over Hawkesbury sandstone but with underlying hanging swamp in places. The vegetation is heath-like with low growing trees until the last section of the track which becomes a denser woodland until the cliff top is reached.
Mount Annan Plantbank Visit 27/7/17
About a dozen members and friends visited the Mt Annan Plantbank on Thurs 27 July. It was a beautiful day – cool and crisp with hardly a cloud in the sky. We were met by our guide at the Plantbank entrance and proceeded on our tour of the working areas of the facility.
The general aim of the Plantbank is to preserve and study the seeds of all 6000 plus plants in NSW and the 25000 plus plant species in Australia. Staff mount gathering trips periodically to bring in seed from different species. Samples are usually representative of the plants in the wild rather than just the best specimens. Most are dry land plants where the seed can be preserved fairly easily. The active part of the seed is separated from the surrounding chaff, it is then dried at 15DC and 15% humidity, then sealed in metal foil packets and stored in the vault at -5DC. For most species this will maintain the ability to germinate for many decades up to hundreds of years. Not all of the sample is stored at Mt Annan – parts are forwarded to other plantbanks around the world. Mt Annan’s major partner in this process is the Millenium Seedbank at Kew Gardens in the UK.
Wet area plants and rainforest plants are not as easy to handle. The seeds are often larger with more flesh and require specialised techniques to preserve them. Plant tissues and seeds are prepared in special bottles and then stored in the vapour from liquid nitrogen at -196DC. This process preserves them almost indefinitely.
The Plantbank building is an excellent facility and cost $20 million to build. It has been going for some years now and will take another 20-30 years to accumulate all the species of interest – it has plenty of capacity to accommodate this. As existing samples age there will also be the need to replace them periodically. The Plantbank also has a nursery to check seed viability in a practical way and this also provides specimens for the Botanic Garden and various ecological experiments.
Our group really enjoyed our visit – it was stimulating and inspiring to see the work under way.