White Beech: The Rainforest Years (45 page)

She sat down again. ‘Listen to this:

Ever since continental drift and plate tectonics displaced the stable earth model in geological theory, the Proteaceae have been generally regarded as a classic ‘Gondwanic Group’ – one that originated well before the fragmentation of the ancient supercontinent Gondwana, and which achieved its widespread distribution in the southern hemisphere as a result of vicariance.

‘Vicariance?’

Jenny explained. ‘It’s the word they use for what happens when the range of a species is split and two different species evolve from a common ancestor. It’s only a theory. If it’s correct the distribution of taxonomic groups has been determined by ruptures in the range of ancestral species, by continental drift or an eruption or a flood. What our colleagues were trying to do was trace the splitting process by a phylogenetic examination of a group of Proteaceae. However’ – Jenny paused for dramatic effect –

However, molecular dating analyses recently conducted by Dr Weston’s research group are suggesting that the first of these ideas is false and the second only partly true.

‘Then, what . . .?’ I stared at her. I’d just got my head round the Gondwana hypothesis and here it was disappearing like the Cheshire Cat, leaving only Jenny’s delighted grin behind.

‘Wait,’ she said. ‘There’s more.’

Mast et al. (2008) published the results of a phylogenetic analysis and molecular dating of the most biogeographically interesting clade in the Proteaceae, the tribe Macadamieae—

Jenny turned to me. ‘Which would be?’

I had to ferret in my files for the answer. ‘The tribe is made up of four subtribes, the Macadamiinae, the Malagasiinae, the Virotiinae and the Gevuiinae.’ The Macadamiinae are three genera,
Macadamia
,
Panopsis
(from tropical America) and
Brabejum
(from the south-west Cape); the Malagasiinae two,
Malagasia
(from Madagascar) and
Catalepidia
(from Queensland); the Virotiinae three,
Virotia
(from New Caledonia),
Athertonia
(Queensland) and
Heliciopsis
(Burma to central Malesia); and the Gevuinae seven or eight, depending,
Cardwellia
(Queensland),
Sleumerodendron
(New Caledonia),
Euplassa
(tropical America),
Gevuina
(Chile and Argentina),
Bleasdalea
(western Pacific to eastern Australia),
Hicksbeachia
(up the road from Cave Creek),
Kermadecia
from New Caledonia and
Turrillia
(probably synonymous with
Bleasdalea
). OK?’

Jenny turned back to the computer screen. ‘The analysis was based on DNA sequence data for seven nuclear and chloroplast genes plus morphology. Are you with me?’

I thought so. ‘Hang on tight,’ said Jen.

Their results strongly suggest that at least 8 of the 9 clades in this tribe showing continental disjunctions are too young to have dispersed between the continents over land.

‘What?’ I was dumbfounded.

‘Hold on,’ said Jen.

It suggests—

‘What suggests? That “it” has no antecedent.’

‘He’s a botanist. You can’t expect grammar.’

It suggests instead that what is now the Australian craton is the centre of origin for this tribe and that the clades now found in tropical and temperate South America, New Caledonia, Fiji, Vanuatu, south-east Asia, Madagascar and southern Africa got there by long distance dispersal across significant ocean gaps. Moreover, the reconstructed dispersal events all post-date the onset of the circum-polar current and are significantly correlated with multiple evolutionary origins of indehiscent fruits, suggesting that the intact fruit wall has played a key role in protecting the seed from immersion in salt water.

The suspicion that the commonly accepted version of the evolution of the Proteaceae was wrong had been around for years. Nigel Barker, who began working on the Proteaceae as a graduate student in South Africa, was granted a fellowship to work at the Royal Botanical Gardens in Sydney with Peter Weston in 1996 and formed his hypothesis then, but it was not until he met Frank Rutschmann, who was completing a Ph.D. at the Institute for Systematic Botany in Zurich, that he was able to avail himself of the newest computational expertise in molecular dating. Hervé Sauquet’s revision and reassessment of the fossil evidence completed the array of skills needed to calibrate the molecular clock as the mutation rate of the various DNA sequences they had assembled was established by comparison with that of the fossils. The genus
Protea
turned out to be genuinely Gondwanan but other of the fynbos genera were much younger and had closer Australian relatives (Barker, N.,
et al
.).

In 2005 botanist Robert Price introduced me to Christopher Spain, a student from Southern Cross University who was studying the genetics of
Macadamia tetraphylla
and needed a sample to analyse. I showed them trees high up in the forest, and on the edge of the cleared land and down on the creekside. Eventually Rob and Chris marked out a quadrat and Chris went to work. The upshot was that the selected trees were genetically identical. It was back to the drawing board for the proponents of accidental hybridisation.

I took a chance on another proteaceous species as well. I hadn’t seen a Floydia at Cave Creek, but I knew it had to be there. It was the tree that Ferdy Mueller had originally called
Helicia praealta
; Bailey then decided that, like another of Mueller’s Helicias, it was a Macadamia (
The Queensland Flora
, 4:1330); in 1975 Lawrie Johnson and Barbara Briggs finally determined that it was a distinct genus, and called it after our guru, Alex Floyd (APNI). The name didn’t appear on Jinks’s survey, but every now and then as I rambled around the forest I would pick up a perfectly round and perfectly rotten nut, about the size of a squash ball, that seemed as if it had to be the Ball Nut that gives the Floydia one of its common names. It is also known as Big Nut and Possum Nut. Floyd remarks that the woody outer shell of the Ball Nut encloses one or two seeds ‘which are somewhat bitter’. Another popular reference book updated as recently as 2009 declares that the fruit of
F. praealta
is downright poisonous (Leiper
et al.
, 334).

Floydia is listed as endangered, which made it even harder to resist the impulse to plant it, but we couldn’t find it on the property. I weakened and, breaking all my own rules, bought in twenty from a nursery. One day I was botanising on the old snigging track with Rob, when he stopped to look at some fallen blossoms among the leaf litter. He held one up, so I could see that it was a short helical raceme of tiny tubular flowers that split into fours, with a style projecting from each.

‘Floydia,’ he said.

‘Where?’ I squinted up into the canopy forty metres above our heads.

‘Here.’ Rob slapped his palm against a solid column that soared into the foliage far above us. I swung the binoculars over my shoulder and peered through them. I was looking for the lanceolate leaves with the wavy margins that I knew from the baby trees.

‘I can’t see it,’ I moaned.

‘That’s because the canopy leaves are smaller, and don’t have wavy margins. This is it all right.’

‘Good Lord! Everyone says Floydia’s a middle-sized tree. This is huge. This must be the biggest ever recorded.’

Someone has revised the data on
Floydia praealta
, because the new edition of Floyd says it grows up to thirty-five metres and sixty centimetres in diameter. Cave Creek isn’t listed among the places where it does that, which is fine with me. The giant Floydia is beyond price, more than we could ever have hoped for. The best way of keeping it safe is to create a haven for it, and keep it well away from people and barbecues and four-wheel drives. That’s what they haven’t been able to do for another recently identified proteaceous species, the Nightcap Oak, one of only two species in a sole genus in its own subfamily, with the scientific name
Eidothea hardeniana
. The binomial is cooler than usual: Eidothea, for whom the genus was named in 1995, is one of the daughters of the god Proteus; the name given to the second species found in 2006 honours a woman, one of very, very few. She is Gwen Harden, distinguished editor of
The Flora of New South Wales
and one of the authors of the field guide
Rainforest
Trees and Shrubs
, otherwise known as the Red Book, that we use every day. The entire population of
Eidothea hardeniana
numbers only sixteen trees living somewhere in the Nightcap National Park. The whereabouts of the Wollemi Pine was kept a secret too, but walkers found it, brought pathogens into the gorge with them, and
Wollemia nobilis
is now said to be extinct in the wild. The only place for the vulnerable Floydia is in the wild, the unvisited wild, nowhere near the beaten track.

It’s easy to become obsessed by the Proteaceae. The family numbers about eighty genera – I say about because they’re always changing. About half of them are Australian, a quarter South African, the rest are endemic to South America, New Caledonia, New Guinea, Malesia, South and East Asia, tropical Africa, Central America, Madagascar, New Zealand, Fiji, southern India, Sri Lanka, Vanuatu and Micronesia. They are a quintessential Gondwanan family.

‘Funny isn’t it?’ said I to Jenny. ‘In Enzed you’ve got two genera of Proteaceae and both are monotypic, making a grand total of two species. Mind you, there are many monotypic genera in the family. Out of forty-two genera in Oz sixteen or seventeen have only one species. Isn’t it odd that New Zealand only 2,000 ks or so off the coast of Australia should have only two proteaceous species when Australia has more than 850?’

Said Jenny, ‘There used to be many more; they’ve found a high proportion of different kinds of proteaceous pollen in coal deposits in the South Island. You have to remember that New Zealand suffered a massive extinction event at the end of the Cretaceous and then most of it gradually sank below sea level, so it was just a chain of small islands. These grew into today’s New Zealand, as the Australian and Pacific tectonic plates kept on grinding against each other and pushing up new mountains, and the vegetation was regularly incinerated by eruptions. So the biodiversity took a bit of a hit. How many proteaceous species have you got on this property?’

‘More than you’ve got in the whole of Enzed. Let’s see. There’s my precious
Macadamia tetraphylla
, which grows in isolated patches in the coastal ranges from the Richmond River northwards.
Grevillea robusta
, on the other hand, grows all over the place. It’s as common as dirt and we have thousands of them, but I tolerate them because the bowerbirds love them. We’ve got a Triunia, as well. I assumed it was
Triunia
youngiana
when I first collected it, but the flower doesn’t seem quite pink enough, and it has a dusting of moss green, almost metallic.
Orites excelsus
,
Stenocarpus sinuatus
. I found a Helicia growing down on the creek,
Helicia glabriflora
I suppose, but the inflorescence is a bit more gracile and greener than the type. It’s supposed to have dark purple fruit, but I haven’t found any yet. And then there are the Floydias.’

‘What – no Banksia?’

‘There’s one near the old house.
Banksia filicifolia
. It grows on the rhyolite; I don’t know how one ended up down here, but we’ve propagated it because the bats and birds besiege it for the flowers.’

I couldn’t stop thinking about Macadamias. It seemed obvious that Aboriginal people would have been eating the Queensland or Bush Nut for sixty thousand years or so before Allan Cunningham is supposed to have ‘discovered’ it in 1828. You might ask which of the two it was he found, Queensland or Bush, because though there is a tendency to call
Macadamia integrifolia
the Queensland Nut and
M. tetraphylla
the Bush Nut, the practice is not consistent. For example, Tom Cowderoy recording his childhood in Numinbah in the 1890s says that Aborigines used to turn up in the valley ‘when the Queensland nuts were ripe’ when the nuts that grow in the Numinbah Valley are
M. tetraphylla
. Jenny Graham, a Kombumerri woman from Beechmont, is said to have told her grandchildren that as a young girl she would carry nuts with her when she travelled and plant them along the way. ‘The Macadamia nut trees that can still be seen on the upper reaches of the Nerang River may be the same ones she planted as she strolled as a child around the 1870s.’ (O’Connor, 33)

When I read that I yelped so loud that Jenny spilt her tea.

‘For goodness’ sake. Is there no end to this Kombumerri nonsense? Here they are trying to get me to believe that they planted the Macadamias on the Upper Nerang!’