Research at the Australian National Botanic Gardens

The Revwattsia Story

Dr Christine Cargill
Curator of Cryptogams, Australian National Herbarium

There are times when perseverance or persistence does pay off in science !

The Revwattsia story begins way back in 2001, the first year I was here as the Curator of Cryptogams at the Australian National Herbarium. As part of the research component of the position, I had begun the axenic or sterile culture of bryophytes (mainly hornworts and liverworts but with the odd moss thrown in there from time to time) from spores. These could be used in experimental work or for DNA work, as they would not have any contamination from fungi, bacteria or other organisms. Jim Croft and David Jones approached me and asked if I would have a go at growing the rare North Queensland epiphytic fern, Revwattsia fragile, from spores that David had collected on one of his trips up north. I was happy to have a go, having grown the gametophyte stage or fern prothallus many times for first year biology classes at Monash University. In this case I merely sprinkled the spores onto a few plates of agar (so this was not strictly a sterile culture) and waited to see what happened. After a few weeks, tiny green fern prothalli appeared along with bacteria, mould and green algae ! I carefully pricked out the prothalli and transferred them onto new agar in sterile baby food jars, hoping to lessen the contaminants. The green algal contaminant continued but it did not seem to worry the young prothalli.

Many weeks and months went by, the fern prothalli multiplied, exhausted the nutrients in the agar, and I would occasionally transfer them onto new media. After a while I pretty much ignored this culture, other projects were more pressing.

Two years later, I was looking through all my cultures, and much to my surprise, two or three young sporophytes (the leafy green stage of the ferns that most people will be familiar with) were emerging from the parent prothallus of the Revwattsia. This is the first record in the world of culturing from spores and the complete cycle observed of this species. All three of us were quite excited. At around about this time, the Australian Flora Foundation   http://farrer.riv.csu.edu.au/ASGAP/aff.html was offering small grants to foster research into the biology and cultivation of Australian plants.

Young sporophyte (or fern on the left) growing out of a clump of fern prothalli (on the right). Photo : David Jones

With the encouragement of Jim Croft, David Jones and I have applied for such a grant to expand our initial culturing into a project to determine the optimal conditions for growing this fern. The ultimate aim is to develop a straightforward protocol for the culturing of this fern. It would then initially be offered to all the major Botanic Gardens across Australia and perhaps eventually be offered to the horticultural trade.

And the reasons for selecting this particular fern for such a project? The answer is two-fold : it's habit and it's rarity.

Revwattsia fragile has spectacularly large (up to 2m long) compound leaves not unlike those of tree ferns in an epiphytic habit - perfect for hanging baskets in sheltered areas or as indoor plants, as per photo below :

The only live collection of the fern Revwattsia fragile at the Australian National Botanic Gardens with Cryptogam Curator, DR Christine Cargill Photo : Murray Fagg

Revwattsia fragile is known from only six locations in the rainforests of northern Queensland and this is an opportunity to develop a long-term conservation strategy along the same lines as that for the Wollemi Pine.

It is a rare plant, which is spectacular to look at, and could potentially become a collectors' "must have". This could be alleviated if the ferns were available through commercial nurseries, thus reducing pressure upon natural populations. It is also an opportunity to showcase one of the many interesting and spectacular Australian plants.

 

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The Ellis Rowan Garden Two Years On

David Taylor
ANBG Senior Horticulturist

The plants in the Ellis Rowan garden are progressing well since their planting in 2003, with many plants starting to establish their form and character. Dan Marges (the iconic custodian of this section) is carefully guiding these plants to maturity.

The plants were initially planted closely, to ensure a combination of instant and massed effect. Subsequent care has required the need for some targeted and discreet thinning and pruning to allow the area to retain its vibrancy and harmony, without any obvious signs of 'gardening' having been done. For example :

Acacia leprosa 'Scarlet Blaze'. The amazing red-flowered wattle can produce a lot of new growth when conditions are favourable (as these ones did last spring). This can lead to the plants becoming top heavy and even blowing over - a potential heart breaker !  To avoid this we have carefully pruned them three times this growing season, taking excess weight out of the crown. At the same time, we have carefully lifted them to arch just above passers-by. There is a chance that this could lead to visitors being caressed on their heads, and at flowering time, gently showered with red wattle flowers. (We hope that you cannot see evidence of this work and that they look quite natural).

Correa bauerlenii has needed regular tip pruning so it does not smother nearby friends (the plant kind). As can be seen in this garden, it responds well to this regular light pruning, and could even be formally pruned, if so desired, into something bizarre such as a set of chess pieces or a small pony ! ?  (Very unlikely at the ANBG, but something people could try at home.)

Other plants have been allowed to develop naturally. For example the Banksia spinulosa 'Stumpy Gold' are starting to hug the boulders as we had hoped. They are a good example of a plant with form that happily merges together with little need for 'steering' with the secateurs. If you have a good imagination you could almost see them hugging granite rocks by the sea, which is where many of these dwarf or miniature forms of Banksia spinulosa have their origins.

Dianella tasmanica has been simply left to its own devices, and is 'clumping up' nicely in the lower parts of the simulated dry creek bed.

When the area was planted we placed a strong emphasis on the plants selected for the garden blending with others nearby; this was based on each group having a key common characteristic connecting it with the next group (with the intention of having an area that is mostly 'easy' on the eye rather than a garden of dramatic contrast and abrupt change).

There are endless options for mixing and matching using this technique. It is a good idea to group plants still in their pots on the ground to see if the groups 'work' well together side by side, before planting them in their final position.

In some cases we matched similar foliage types/shapes as in the oval foliage of Leptospermum 'Lavender Queen' with Platyscace lanceolata 'Edna Walling Flower Girl'. Another combination matched shiny bright foliage as in Correa bauerlenii with Libertia paniculata and Blechnum nudum. The combination of Lomandra confertifolia ssp rubiginosa with the grey foliage of Chrysocephalum apiculatum and Grevillea dimunata relied on matching foliage colour. Form was used to blend species as in the case of the horizontal habit of Homoranthus pappilatus with Micromyrtus ciliata.

Correa alba (compact form and Correa 'Western Star' have started to blend with the existing Correa alba next to the cafe, tying together the old and the new and showing the variation and combinations possible within the Correa alba group and its progeny.

We once again thank the Friends for their contribution enabling us to make this garden happen. Both the partial funding, the invaluable 'What's in Flower' guide and regular feedback have helped bring the Ellis Rowan Garden to where it is today.

The Ellis Rowan Garden before its redesign   Photo: Graig Cosgrove

The garden just after replanting Photo: Graig Cosgrove

The garden two years on          Photo: Barry Brown

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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The Queensland Bottle Tree

Stuart Donaldson
Collections Officer

A unique slow-growing Australian species, the Queensland Bottle Tree (Brachychiton rupestris) has adapted from its rainforest heritage to the long dry periods of the Centran Queensland scrub. The young roots and seeds (raw or roasted) were eaten by Aboriginal people. Today the trees are being harvested to satisfy horticultural endeavours and pushed over to allow cattle to graze during drought.

While searching for suppliers of Macrozamia moorei in Queensland, Toby Golson, ANBG Rainforest Horticulturist, came across an international supplier of the Queensland Bottle Tree. One thing led to another, and the strategy of creating a front entrance using iconic and striking Australian species was able to be met. The specimen at the entrance to the Gardens is flushing well and the bronzy new foliage is evident; hopefully it will flower as well.

There are other fine specimens of the tree in the Gardens' collection - one in section 42, one in section 302 and a group of four in section 220 that were transplanted from the Top Depot area in 1995.

Once again, we thank the Friends for the funds to buy, transport and crane the tree into position. More information about Brachychiton species and their close cousins the Baobabs, is available in the ANBG Library.

Photo : Barry Brown

The Eastern Spinebill

Tom Green
Member of the Friends of the ANBG

Photo :  Geoffrey Dabb

There can be few better places to spend a crisp spring morning than in the ANBG surrounded by wildflowers and the sounds of our native birds. After the success of 'Breakfast with the Birds' I thought the Friends might enjoy some articles on the birds of the Gardens.

Perhaps the busiest bird in the Gardens is the Eastern Spinebill. The spinebill is instantly recognisable as a blue-metal grey bird with a large white 'flash' on each side of its tail and a very long down-curved bill.

At a slim 15 cm long, and weighing only 10 grams, the spinebill is the smallest honeyeater in the Gardens and its white outer tail feathers are constantly flashing as they twist and dart away from pursuing birds. When the spinebill pauses long enough at a flower you may be able to see its white throat and chin which are separated from its rich rufous underside by a dark yolk across the upper breast. Adults have a smudge of brown in the centre of the white throat patch. Immature birds are clad in sober brown and fawn but still carry the long fine bill that sets them apart from the other honeyeaters.

Eastern Spinebills are nectar feeders although they also take small insects, particularly while breeding. They are resident in Canberra through the year and so are especially dependent on the winter flowering Grevillea such as G. lanigera and G. alpina. In late winter a great place to find them is among the G. lanigera 'Mt Tamboritha', in the garden below the Visitor Centre. In the spring they are driven away from rich nectar sources by aggressive larger honeyeaters, but their light weight and long bill enable them to exploit small flower clusters on the tips of fine foliage. Then they can be found down in sections 28 and 29 feeding on Grevillea such as G. newbeyi and G. australis. In the hot summer months they are content with the sparse flowers on G. asteriscosa and Melaleuca thymifolia when bigger honeyeaters have moved on to the lush flowers of the alpine meadows.

Eastern Spinebills are spring nesters. They build a neat cup next 55-6 cm in diameter, suspended in the outer foliage of a dense tree or shrub. The nest is usually 2 to 3 metres above the ground and prickly leaved plants are preferred. A new nest is built for each breeding attempt so several nests may be found in very suitable shrubs such as the Lilly-pilly in the very eastern edge of section 40.

Growing Australian Plants

Anne Phillips
Member of the Growing Friends

Grevillea lanigera - Woolly Grevillea

Family : PROTEACEAE

Photo : R Hotchkiss

Grevillea : after C.F. Greville (1749 - 1809), one of the founders of the
                  London Horticultural Society.

lanigera: Latin: lana, wool + gerus, bearing - referring to the woolly leaves

Distribution : NSW, Victoria                 Propagation  : from cuttings

Grevillea lanigera is a prostrate shrub 0.5 - 1m high x 1 - 2m wide, with flowers of red and cream in semi-erect clusters appearing in late winter and spring. It is very hardy, and will grow in most soils in a sunny position. It looks particularly good in a mass planting.

In the Gardens it can be found in section 223 in the terrace bed in front of the Visitor Centre, section 24 along the main path, section 300 beside the Eucalypt Lawn and throughout the Gardens.

Grevillea lanigera, along with other interesting plants, will be available at the Growing Friends Plant Sale on Saturday, 2 April, from 9 am until 11 am.

Friends Briefs

Annual General Meeting

The 16th AGM of the Friends of the ANBG was held on Tuesday 8 February. It was very well attended by Members of the Friends. The President of the Friends, Andrew Walker, presented the year's report on activities, followed by a report from the Director of the ANBG, Robin Nielsen. Then there was the election of office bearers and Members of the Friends Council; all except one of the existing members were re-elected for a further two years. John Burdett, who has energetically served on Council for several years, stepped down, and was replaced by Elizabeth Bilney. Many thanks to John Burdett for his contribution to the work of the Council.

Once the business end of the meeting was over, Dr Jim Croft, Deputy Director of the Gardens, gave an interesting talk on Ideas and Aspirations for the Gardens (click here to view the presentation). Interspersed within the presentation were some apposite quotations on friends, gardens and gardening. Jim has kindly given us permission to share these with you, and we will try to include several of these quotations in the next few issues of the newsletter.

Public Fund

The ANBG Friends Public Fund, established this year to provide substantial support for Gardens' projects, has had a very successful beginning. Already nearly forty donations have been received. All donations over $2 are tax-deductible. For further information

 

Friends Botanic Art Group :    Click here for full information.

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