Gondwana on our doorstep

For me, one of the joys of the Australian National Botanic Gardens (ANBG) is the rainforest gully. I first ‘got into’ plants many years ago when I lived in Tasmania and spent much time working in the cool temperate rainforests there. I became acquainted with such iconic trees as the Myrtle Beech (Nothofagus cunninghamii), Southern Sassafras (Atherosperma moschatum), Huon Pine (Lagarostrobos franklinii) and Leatherwood (Eucryphia lucida) which flourish in the lower reaches of the gully.

I’ve been fascinated with cool temperate rainforests ever since. They are like time capsules, ancient relics from the past when Australia was part of the supercontinent of Gondwana and these forests dominated the land. But when Australia broke free about 50 million years ago and became drier and more arid, they shrunk considerably, giving way to tougher competition such as the Eucalypt forests.

Unknown to most people, small pockets of cool temperate rainforest survive in southern NSW, in the sheltered valleys of the coastal escarpments at high altitude, where the rainfall is high and misty cloudy weather is frequent. However the dominant tree here is the Plumwood (Eucryphia moorei), a close relative of the Tassie Leatherwood, and named for the pink or plumy colour of its wood. It ranges from Bulli Pass near Wollongong to the Howe Range just over the border in Victoria.

The fossil records show that the Eucryphia genus was widespread in Gondwana. There are now only seven species in the world – two in Chile and five in Australia. A second species in Tasmania is a smaller montane version of the Leatherwood, once considered a variety. And in recent times two new species with very restricted distribution have been discovered – one in the cloud forests of the wet tropics in 1970, and the other in the subtropical forests of northern NSW/Southern Queensland in 1994.

Some of the largest and best examples of Plumwood forest can be found in Monga National Park, about 20km south-east of Braidwood. The trees here can reach enormous sizes and ages, with some ancient specimens reportedly measuring four metres in width and estimated to be two to three thousand years old.

Penance Grove is an easy and delightful spot to view the Plumwoods of Monga. Turn off the Kings Highway at River Forest Rd and follow the signs south. A raised 240m boardwalk with interpretive signs leads you through the wonders of this magical grove which evokes what the ancestral forests of 100 million years ago probably looked like.

Due to low light levels, the understorey is sparse and dotted with graceful tree ferns which provide a high platform for Plumwood seedlings to germinate out of reach of nibbling swamp wallabies.  As they grow, they extend their roots to the soil below before eventually encompassing the host plant. Sadly, a few of the tree ferns have been ‘beheaded’ by illegal plant collectors in recent years.

The Plumwood is an attractive tree due to its pinnate leaves (which are unique for this genus) and its large cream-coloured, strongly scented flowers. If you visit in early Autumn, you’ll see the petals sprinkling the rainforest floor like snowflakes.

The genus name Eucryphia was bestowed by Melbourne Botanic Gardens Director, Baron Ferdinand von Mueller in 1863, with the name derived from the Greek for ‘well hidden’, referring to the cap which is formed by the sepals. The specific name is in honour of botanist Charles Moore, Director of the Sydney Botanic Gardens from 1848 to1896.

Plumwood  trees can also be seen in the rainforest gully at the gardens. Next time you visit the ANBG, look out for five or six specimens on the Main Path on the southern side of the creek just to the west of the café.

Plumwood at gardens
Plumwood tree along the Main Path at the ANBG.
Penance Grove
Penance Grove walking track in Monga National Park
Pinnate leaves
The unique pinnate leaves of the Plumwood
Plumwood Flower ANBG M. Fagg
Plumwood flowers (Credit: ANBG)

The Cootamundra Conundrum

Cootamundra Wattle at Jindalee National Park 1 Bipinnate leaves and flowers of Acacia baileyana (Cootamundra Wattle);
Captions: Acacia baileyana (Cootamundra Wattle) growing at Jindalee National Park; The bipinnate leaves and flowers of Cootamundra Wattle. Photos: J. Lynch

Cootamundra Wattle (Acacia baileyana) first caught my attention when I moved to Canberra six years ago. Its bright yellow clusters of ball-shaped flowers produce a stunning burst of colour during the cold winter months, and it retains its attractive grey-green, fern-like, bipinnate leaves throughout its life. Growing to between three to 10 metres in height, it thrives in cool, higher rainfall areas and is very adaptable, hardy and fast-growing. No wonder it is such a popular garden plant.

Cootamundra Wattle is so ubiquitous in the open spaces of Canberra, I initially thought it must have been native to this region. However, I soon discovered that it is a pest plant in the ACT and that many volunteers spend countless hours removing it from our bushland reserves. It is also classified as an environmental weed in many other parts of Australia (Western Australia, South Australia, Queensland, New South Wales and Victoria) as well as overseas in New Zealand and South Africa.

For such a hardy and prolific plant which grows so well in a wide range of climates and soils, Cootamundra Wattle intriguingly had a very restricted natural distribution at the time of European settlement. It only grew in the vicinity of Cootamundra, hence the common name, between Stockinbingal, Temora, Cootamundra and Bethungra (a distance of only about 50 km, east to west). Despite this, it is not considered to be at risk in the wild. Unsurprisingly, it is the floral emblem of Cootamundra and is on the logos of many local businesses, organisations and the Shire Council.

A.baileyana was first described by Baron von Mueller in 1888. He named it after the Queensland botanist Frederick Manson Bailey who collected the type specimen from a cultivated plant in Bowen Park, Brisbane in 1876. Bailey was a prolific botanist who made valuable contributions to the characterisation of the flora of Queensland and was Colonial Botanist of Queensland for many years.

In 1935, the botanist Mr I.V. Newman undertook a seven month study on the status and natural range of Cootamundra Wattle, going some way towards trying to explain its contradictory character. He reported that across its native range the species was limited to elevated sites near the crest of the divide, at an altitude of between 400 and 800 metres, on outcrops of Silurian sedimentary rock associated with patches of granites and porphyries (igneous rocks with large crystals such as quartz), with an average annual rainfall of between 18 and 23 inches, and sheltered from the south and west by the high ground of the range. The only other similar area in NSW was a much smaller area just to the north.

These facts led him to hypothesise that ‘it seems possible, therefore, that it is a relict of a species which may have flourished widely before physiographic changes initiated a losing battle between it and the environment’; and later: ‘It is either an old species living in a restricted habitat or it is a new species that did not spread far before the coming of settlement’. Perhaps we will never really know.

What we do know is that it is now a weed. Waltraud Pix, the Coordinator of the Friends of Mt Majura Parkcare group for 10 years until 2013, actively coordinates the restoration of endangered Yellow-box Red Gum Grassy Woodland at a site in North Watson every Friday morning, where one of the main activities is eradicating Cootamundra Wattles by either the ‘cut and paint’ or ‘frilling’ methods. I asked her recently why they are such a problem. ‘The mature trees produce large quantities of seeds every year, which are spread by water and birds over large distances and remain viable in the soil for decades,’ Waltraud said. ‘It easily invades our natural areas, especially after any disturbance, and competes with native shrubs, small trees and ground flora. They can form dense thickets excluding light and preventing the regeneration of indigenous native species.’

‘Cootamundra Wattle also frequently hybridizes with the local closely related Silver Wattle (A. dealbata), which could potentially threaten the long term survival of Silver Wattle in this area,’ Waltraud added. ‘Therefore I suggest to anyone with Cootamundra Wattle in their gardens, especially if they live near bushland, to replace it with a non-invasive species sold from bush friendly nurseries.’

The best place to view Cootamundra Wattle in its natural habitat is Jindalee National Park, which covers an area of 1,076 hectares and supports isolated stands of near threatened and vulnerable open forests dominated by Red Ironbark, Grey Box, Black Cypress Pine, Red Stringybark and Scribbly Gum. It was only recently declared in 2011 after many years as a state forest. The wattles are most plentiful in the, smaller south-eastern section of the park on the right hand side of Berthong Road, approximately 14 kilometres north of Cootamundra. Drive in through the gate, park in a suitable spot and just take a walk around. Specimens growing in the dense regrowth forest tend to be somewhat spindly whereas in open sites they are much more robust and profuse, with many large thickets to be found. Unfortunately, the park suffers from the effects of illegal dumping, vehicle access and fire wood collection.

A few years back a Cootamundra Wattle self-seeded in my back garden, which left me in a bit of a quandary. At first I was loath to remove it, but as much as I enjoyed its splendour, I eventually bit the bullet. Now there are a few Silver Wattles growing in its place, which are just as splendid.

Written by Jo Lynch. Originally printed in ‘Fronds’, the newsletter of the Friends of the Australian National Botanic Garden Number 77, August 2014


The blue amongst the green

The blue amongst the green

One of my favourite trees at the Australian National Botanical Gardens is the Argyle Apple (Eucalyptus cinerea) on the Children’s Discovery Walk. Adorned with Gang Gang Cockatoos and many kinds of colourful plastic insects, it inspires little minds to explore the myriad life that trees support.

The Argyle Apple is a very attractive tree with thick rough red-brown to grey-brown bark and visually appealing opposite, blue (glaucous) juvenile which often persist on the adult trees. As such, it is a very popular street and garden tree, and its leaves often turn up in floral arrangements.

Its natural distribution is from north of Bathurst to the Beechworth area of Victoria, but the Goulburn region is its major ‘hotspot’. Its common name is derived from its occurrence in Argyle County, an early name for the Goulburn district. To see it in its natural habitat, I contacted Rodney Falconer, Vice President of the Goulburn Field Naturalists and author of the local native plant guide Down by the Riverside. Always happy to generously share his encyclopaedic knowledge of the area, he immediately offered to take me to Towrang, which was, he said ‘the Argyle Apple centre of the universe’.

I met Rodney on a brisk cold mid-winters day, and as we drove to ground zero, Rodney explained how the Argyle Apple grows on what the locals amusingly call ‘Shitite’ soils. These are shallow, stony and relatively infertile, compared to the deeper more fertile soils which support the more widespread Yellow Box / Red Gum Grassy Woodlands. ‘The Argyle Apple is mostly found on the midslope between the drier hill tops of Brittle Gum forest and the lowland grassy woodlands. It rarely dominates, instead forming a part of the woodland vegetation along with other eucalypt species’.

Arriving in Towrang, about 10 kilometres east of Goulburn we cruised along the roads outside of town. Sure enough there were Argyle Apples everywhere, including some beautiful remnant groves surrounded by farmland. The main thing I noticed was that many of the trees were often smaller and more twisted than those you see around Canberra, reflecting the poorer soils. The other thing I noticed was that all the trees we saw were either growing along the road sides or on private property. ‘Yes, unfortunately none of the Argyle Apples around here are protected in any kind of reserve’, confirmed Rodney. ‘So they are all at risk from clearing which highlights the need for conservation on private land’.

I later contacted the NSW Office of Environment and Heritage to clarify its conservation status. It is found in a few protected areas, mainly in the inaccessible Tarlo River National Park and remote parts of Bungonia National Park. However, they confirmed it is not well represented in conservation reserves across its natural range.

Next time you travel along the Hume Hwy between between Goulburn and Marulan, look out for them growing alongside the road, the blue amongst the green. And stop at the Chownes VC Rest Area, a few kilomatres past the Towrang Rd turnoff along the northbound lane, for a closer look at these beautiful trees in their natural environment.

Written by Jo Lynch. Originally printed in ‘Fronds’, the newsletter of the Friends of the Australian National Botanic Garden Number 75, December 2014

E. cinerea Image 1E. cinerea Image 2E. cinerea Image 3E. cinerea Image 4

Captions: E. cinerea on Children’s Discovery Walk ANBG; a grove of Argyle Apples near Towrang, NSW; Argyle Apple woodland vegetation, showing the more gnarly growth form of many of the trees; Juvenile foliage. Photos: J. Lynch