White Beech: The Rainforest Years (40 page)

To
Ficus watkinsiana
are sometimes attributed the spots clearly visible on the fig species collected by Banks and Solander, but this species is also called the ‘Nipple Fig’, as if the nipple at the base of the fruit was diagnostic; in our experience spots and nipple do not always occur together. Watkins’s fig is also known as the ‘Grey-leaved Moreton Bay Fig’ and the ‘Green-leaved Moreton Bay Fig’, as well as
F. bellingeri
and
F. simmondsii
. How it could be all these at once is nowhere explained.

So much for our large-leaved figs. Some of our figs are distinctly small-leaved and you would think that they had to be
Ficus obliqua
. Aha no. They have fruits of different colours; some mature to red, some to gold, some to orange. Even the revered Bill McDonald has hesitated to give these figs of ours a name. There are plenty to choose from –
F. tryonii
,
virginea
,
backhousei
,
eugenioides
, or
Urostigma obliquum
, which is the name Georg Forster supplied in 1786, or
Urostigma backhousei
, or
eugenioides
. One of our visiting botanists suggested that our small-leaved figs were
F. obliqua
var.
obliqua
. Some of our fig twigs have bright red stipules, so might be
F. triradiata
.

Margaret Lowman, aka ‘Canopy Meg’, who single-handedly invented canopy science, has written that in the rainforest struggle, the strangler figs will eventually win.

The figs . . . germinate in the crowns of trees, extending their roots downward to the ground, rather than conventionally of [
sic
] sending shoots up to the canopy. This habit is termed hemiepiphytic, because the plants begin life as an epiphyte (air plant) but eventually extend down to root on the forest floor. The top-down pattern of fig growth is not only unique among rain-forest trees, but I privately believe it is destined to be the most successful pattern over evolutionary time . . . My prediction is that figs, with their innovative mode of securing a spot in full sunlight and then growing top downward, will dominate the forests. (Lowman, 100)

If the strangler figs win the eternal battle that is the rainforest, they must also eventually lose, because there has to be a forest for them to climb onto and into. When the birds perch in the forest trees and defecate, the crotches where the seeds end up are sometimes only a few metres off the ground, way below the canopy. What is more, if there is nothing to provide a rooting medium in the tree crotch – decaying leaves, fungal matter, frass – the fig seedling will be slow to develop and may die. All the fig species produce huge amounts of fruit, some of them all the year round, yet the proportion of rainforest trees coping with fig invasion is actually quite low. In terms of investment of reproductive energy therefore, figs would appear to do very badly. Some tree species may even be able to repel stranglers by secreting inhibiting chemicals, for the stranglers certainly don’t seem to be having things all their own way.

It is not usually a good strategy on the part of a parasite to kill its host. The fig canopy is thick-leaved and dense, therefore very vulnerable to high winds, while the lacework trunk is too vulnerable to decay for a fig tree ever to live for a thousand years as many rainforest trees can. With a weak trunk and a huge head of spreading branches weighing many tons, the triumphant strangler fig may overreach itself. At Cave Creek several huge figs that topped out above the rest of the forest have recently fallen. One of them, with a canopy that spread over a third of an acre, fell into the national park and scored a king hit on the footbridge, reducing it to matchwood. By some blessed chance, though tourists come in their droves by day and by night, no one was on the bridge when the fig came down. For two days chainsaws roared as the fallen canopy that crammed the gorge was reduced to lumber. Some crafty person collected all the orchids off the tree and hid them, intending to come back later and collect them. (Rainforest orchids, especially the rarer ones, fetch high prices in neighbourhood street markets.) By good hap I found the stolen hoard before it could be collected and took the orchids back into the rainforest.

Lowman is certainly right to see the rainforest symbiosis as an eternal war, but it will be won by no single species. If the rainforest is a lottery (another of Lowman’s parallels) the house will always win.

At Cave Creek rainforest species flower and fruit according to a timetable all their own. Trees on north-facing slopes will flower profusely when trees of the same species on slopes facing east or west don’t even look like flowering. Sometimes it’s available water that seems to make the difference. Most plants will be forced into flower by stress; in the rainforest this seems not to be the case. In a dry season, our trees are less likely to flower; if we get 400 millimetres of rain out of season, as sometimes happens, we will have a burst of flowering afterwards. It pays us to look for fruit in every season but, though we find tons of it, often we find that the fruit contains no seed. The worst offender in this regard is one of the lilly pillies,
Syzygium corynanthum
, which produces sour cherries in stupendous quantities, so that the ground underneath the trees is blazing coral red. I have sat for day after day, gently opening the fruit with a scalpel, hunting for something like an endosperm in thousands of fruits and finding nothing.

‘Stands to reason,’ said Jane. ‘If you expected to live for five hundred years or more, would you bother ovulating every year? You wouldn’t need offspring for every year of your life, would you?’

‘Plenty of trees, most trees in the rainforest, set hundreds of times more seeds than could ever germinate.’

‘And
Syzygium corynanthum
doesn’t. It’s an option, is all I’m saying.’

I considered this for a bit. ‘So you produce the fruit without the seed because you will eventually need the birds to distribute your seed, and you have to keep them interested?’

‘It’s probably not that simple, but, something like that, yes.’

In 1866 pioneer sugar grower John Ewen Davidson (
ADB
), exploring ‘the scrubs round Rockingham Bay’ between Townsville and Cairns, came across a fruiting tree which the Tully River Aboriginal people called ‘Ooray’; he showed it to John Dallachy, ex-curator of the Melbourne Botanical Garden, who had retired to a property near Rockingham Bay. Dallachy was still collecting for the Melbourne Herbarium, where Ferdinand Mueller named the genus for its discoverer,
Davidsonia
, with the specific name
pruriens
(
Fragmenta
, 6:41, 4). At first prospects for its commercial exploitation seemed good: ‘the fruit is dark purple in colour; the flesh a rich crimson, very juicy and of a sharp, acid flavour.’ (
BC
, 23 June 1881)

To ordinary mortals
Davidsonia pruriens
was simply Davidson’s Plum. It is not in fact a plum, not a member of the genus
Prunus
or even of the family of Rosaceae. It was thought to have not only a genus,
Davidsonia
, but a family all to itself, the Davidsoniaceae (Bange, 294) but in 2000 Gwen Harden and John Williams restored it to the family of Cunoniaceae (Harden and Williams, 414). For a while it looked as if the Davidson’s Plum was going to be one native fruit with a future. The Intercolonial Exhibition of 1877 was one of several where potted Davidsonias were among the exhibits (
SMH
, 12 April). This ‘blue-black plum about the size of a duck-egg’ had obvious potential for improvement, and for some time it seems to have been a popular inclusion in Queensland gardens. A reviewer of J. H. Maiden’s
Useful Native Plants of Australia
in 1889 was surprised to find that he had left out such a well-known and common fruit (
Q
, 9 March, 452).

In 1900 F. M. Bailey split the species into two subspecies; the second, which he found on the Tweed, he called
D
.
pruriens
var.
jerseyana
(
The Queensland Flora
, ii:538). This was eventually understood to be a species in its own right. In 1949, plant taxonomist Lawrie Johnson, examining collections of Davidsonia made in north-east New South Wales in 1926, 1939 and 1944, segregated some and labelled them ‘clearly a new species’. There the matter rested until 1958, when Alex Floyd and H. C. Hayes collected specimens of the same plant at The Pocket, north of Mullumbimby, and noticed that unlike the type it was hairless; their samples were placed in the Coffs Harbour Forestry Herbarium and forgotten. In 1977 Graham Watson sent a specimen he had collected on his property at Huonbrook west of Mullumbimby to Gwen Harden and J. B. Williams. More collections were then made, some as far north as Currumbin, but still the species languished without a name until Harden and Williams named it
Davidsonia johnsonii
, in memory of Lawrie Johnson (Harden and Williams, 416). It is fitting that the rarest plant at CCRRS should carry this distinguished name. Mind you, if I should find a new species, I should like to call it
briggsae
, for Barbara Briggs, who was for many years Johnson’s faithful co-worker. Johnson is remembered all over the place, including a whole genus of proteaceous nut trees saddled with the name
Lasjia
(for his initials) and the largest of the Macrozamias, which is
M. johnsonii
, but you will search in vain for a memorial to Dr Briggs.

From the day I became responsible for CCRRS I knew that the survival of
Davidsonia johnsonii
was up to me. On every visit I made sure to see how it was getting on. I directed the workforce to remove competing weed vegetation, including a coral tree that grew amongst its suckers. Imagine my horror when, on the way to visit it one day, I found the top half of the biggest Davidsonia lugged out of the forest and dying beside the track. At first I didn’t believe my eyes, but the elegant compound leaves with their winged stalks and flared stipules were unmistakeable. The workforce was duly hauled over the coals. How could we have been so careless? The answer came that as the coral tree slowly succumbed to repeated doses of poison, its head had snapped off and taken out the head of the Davidsonia as it fell. Simon had removed damaged growths and now the Davidsonia would just have to get on with it. I preached a bit about how much vegetative material had been wasted because we didn’t take the broken bit to a propagator, but the workforce was unmoved. The damaged tree, they thought, would grab its opportunity, which in fact it did.

In December 2004 the New South Wales Department of Environment and Conservation joined forces with the Queensland Environmental Protection Agency and the Queensland Parks and Wildlife Service to produce a 34-page recovery plan for
Davidsonia johnsonii
, which is classed under every system as endangered. On page i the plan says that ‘populations in Queensland have been recorded from freehold land only’, which rather makes you think that before spending scarce resources on helping to generate this expensive 34-page statement, QPWS should have tried to find out where their
D. johnsonii
population actually was and how big it was. Two years ago CCRRS worker Luke came across a clump of more than a dozen plants just over our boundary in the National Park. He showed the new find to an official from the Queensland Environmental Protection Agency, who verified it and left. One way conservation bureaucrats might encourage the owners of private land to do the right thing for their threatened plants might be to say hello when they come to visit, and maybe utter a few encouraging words. So far they would appear to be as inept at people management as they are at environmental management.

The recovery plan gave itself the task of determining the long-term survival potential of our smooth Davidsonias, but the current state of their understanding seems unlikely to serve them well.

In some specimens . . . the female flowers are rudimentary, almost vestigial. At other sites, female parts were normally developed, comprising two fused carpels with four or five ovules (up to seven at one site) per carpel. Those sites with the best development of female parts in the flowers are also the heaviest fruit-bearing stands . . .

The method of pollination of Smooth Davidsonia flowers is not understood. The size and form of the flower suggests that the vectors are likely to be small insects. Bees (including native bees), beetles and ants have been observed visiting the flowers. (
Recovery Plan
, 6)

Seed production was an even greater mystery.

There have only been two instances of seed being found within the fruit of this species.

Possible explanations for the low incidence of seed production by this species may include isolation from compatible plants, lack of production of pollen, no transfer of pollen from anther to stigma, non-viable pollen, self-incompatibility mechanisms, and early abortion of developing embryo. (
Recovery Plan
, 6)