White Beech: The Rainforest Years (44 page)

Macadamias look like many of their Gondwanan relatives. If you have ever had the great pleasure of seeing
Hakea victoria
in her full flaming glory in Western Australia, you would recognise a family trait in the structure and leaf colouring of the juvenile Macadamias at Cave Creek. I really didn’t want to have to destroy them. Hoping against hope, I kept them in the planting lists, and the workforce propagated them, not particularly willingly, because they’d much rather grow the forest emergents that put on three metres of height in a year. The Macadamias were slow, and prickly to boot. But I loved them, we had millions of easily collected seeds, and so we kept propagating and planting them.

Generally speaking, Australian common names are specific, but the names Queensland Nut and Bush Nut have been muddled ever since Allan Cunningham collected ‘a Queensland Bush Nut’ (which he identified as
M. ternifolia
) in 1828. In his report to Governor Darling Cunningham remarked, ‘independent of its highly ornamental habit and refreshing shade afforded by its densely leaved branches, its nuts are produced . . . in such abundance as to be ere long worthy the attention of the farmer.’ (McMinn, 93) It would be more than a hundred years before any Australian farmer would avail himself of the opportunity, even though a correspondent calling herself Pomona wrote to
The Queenslander
in 1876 to point out that ‘The Queensland nut is already in our gardens, and bearing fruits under conditions favourable to its permanent improvement.’ (
Q
, 16 December, 22)

The specimen of the Queensland Nut Cunningham sent back to Kew in 1828 probably sank to the bottom of the vast mass of plant material arriving from all over the world, because it cannot now be traced. The species, or something like it, was collected again by Leichhardt in 1843, according to his note, in the ‘Bunya Bunya brush’ and sent to the Melbourne Herbarium. The area where he found it is now known to have been the Conondale Range. Mueller later wrote on the label ‘Dawson and Burnett Rivers’, which is simply wrong. Mueller collected the plant again himself in 1857, with Walter Hill, along ‘the Pine River of Moreton Bay’. The next year Mueller published his description in the
Transactions of the Philosophical Institute of Victoria
, placing it in a new genus which he called
Macadamia
, after Dr John Macadam, Honorary Secretary of the Institute. The type species name was
ternifolia
, three-leaved, and all the specimens preserved in the Economic Botany Collection at Kew still bear this name. Dr Macadam must have done something to annoy Mueller; two years later he described the Queensland Nut again and decided that it was a member of the south-east Asian proteaceous genus
Helicia
. Though Mueller was using the same material as he had for the earlier description he seems not to have recognised it and made no reference to his own earlier identification. It was Bentham, toiling away in England at his
Flora
, who saw that Mueller had been right the first time and resuscitated the genus
Macadamia
, using the grounds alleged by Mueller in his earlier publication.

Nobody seems to have realised that the plants they were discussing produced palatable nuts of high nutritional value. Dutch botanist Maurits Greshoff, who examined the specimens at Kew, was convinced that
Macadamia ternifolia
was ‘among the most strongly cyanogenetic plants; in the fresh leaf the hydrocyanic content was more than 0.1 per cent’ (
Kew Bulletin
No. 10, 1909, 413). Perhaps what happened at Kew is that Greshoff was given immature kernels to study, possibly in a fermented state. This curious chain of accidents has given rise to the erroneous belief, cherished by American Macadamia growers, that there is a poisonous wild Macadamia species that has never been cultivated. This may have been the Gympie Nut, proteaceous, small-fruited and extremely bitter. It was not until 1897 that Maiden and Ernst Betche collected smooth-shelled Macadamias from Camden Haven, and suggested a new species,
Macadamia integrifolia
, so called because the leaves were less serrate than those of the type. Two years later they decided that they were wrong and reduced their separate species to a subspecies. ‘We found all degrees of transition between the two extreme forms and have been forced to the conclusion that it is merely another instance of the great variability of the Proteaceous trees . . .’ they explained (Maiden and Betche, 1897). Attempts to separate the entire-leaved Macadamias from the serrate-leaved Macadamias failed because single trees were capable of displaying both leaf forms at different stages in their development. There was one point of distinction between them which was not debated: the entire-leaved Macadamias grew only in Queensland (hence Queensland Nut), the serrate-leaved grew on both sides of the border (hence Bush Nut).

In 1954, Lawrie Johnson came to the rescue: the confusion ‘has been due to several causes; firstly semi-juvenile stages of one species resemble the mature stage of the other species in the possession of toothed leaves; secondly two states of the first species have been described under two different names; and, thirdly, the second species has not been named at all’ (Johnson, 1954, 15). In fact Bentham had worked on specimens of both species, but Johnson was on the money. The name he suggested for the second species was
Macadamia tetraphylla
, and those are the Macadamias of the upper Nerang Valley. At least, I think they are. The CCRRS Macadamias are not reliably tetraphyllous; the first stem to appear above ground usually carries whorls of three leaves each, and continues to do so until the first fork; the growths above the fork will show whorls of four leaves – mostly. The leaves however are always serrate, but the flowers are not always pink but occasionally white or cream.

By 1954 the phylogeny of the Macadamia was being obscured by the breeding and cross-breeding of selected strains by American horticulturists who recognised the nut’s commercial potential. The first Macadamia trees in Hawaii were planted as ornamentals in 1882 by William H. Purvis, manager of a cane plantation at Kapulena, who was an enthusiastic plant collector. Forty years later another American, Ernest Shelton van Tassell, tried to grow the nuts commercially, but the trees performed inconsistently, producing nuts of varying quality at varying intervals. The Agricultural Research Station of the University of Hawaii then stepped in. They recognised
M. ternifolia
as having almost sessile leaves in whorls of three or four with serrate and sometimes prickly margins;
M. integrifolia
was described as having spatulate leaves with a distinct petiole and entire margins. As cultivars were developed the two kinds resolved themselves into the rough-shelled type and the smooth-shelled type, with only the smooth-shelled type considered suitable for cultivation. As late as 1957 William B. Storey of the University of California, who described the genus as ‘possibly half a dozen species’, was still having difficulty separating them. In his version
M. integrifolia
was a subspecies of
M. ternifolia
. His account is remarkable because of its geographical detail.

M. ternifolia
occurs naturally only in south-eastern Queensland. Its range extends a distance of about 175 miles, from Beechmont on the south to Maryborough on 25°30' S.
M. tetraphylla
occurs naturally only at the south-eastern extremity of Queensland and the north-eastern corner of New South Wales. Its range extends a distance of about 75 miles, from Mt. Tamborine on the north to Lismore on the south between the latitudinal limits of 28°S and 29°S. The ranges of the two species overlap for a distance of about 15 miles in the Guanabah and Tamborine Creek regions of southern Queensland. Types of trees intermediate in characteristics between the two species have been seen in the regions of overlapping ranges. These are thought to be interspecific hybrids. (334)

This doesn’t quite make geographic sense but it does predict the variability that we have observed in the Cave Creek species. By 1970 Storey had accepted Maiden and Betche, and recognised
M. integrifolia
, but he thought it could be found in the Numinbah Valley. Maybe it can, but not at CCRRS. Perhaps botanists have had so much trouble distinguishing these species because in fact they are not distinct.

Commercial production of improved cultivars in Hawaii got under way in the 1950s. The first country to import and grow Hawaiian cultivars was Guatemala, followed by Australia (Cheel and Morrison, 23). Australia now produces 37 per cent of the world’s Macadamia nuts, Hawaii 22 per cent. New varieties are produced every year, not only in Hawaii but in South Africa, New Zealand and Australia as well. The breeders’ aims are to produce strains that will crop heavily and drop their nuts easily, so that they can be harvested mechanically off the ground, and with thinner and more brittle shells so that the kernels are not damaged when the shells are removed. Nowadays the cultivars have numbers instead of names. No more than 2–3 per cent of the Macadamia nuts produced round the world end up being eaten as nuts; three-quarters of them are processed to go into cakes and biscuits, the rest into chocolates, ice cream – and cosmetics.

We were back in Cambridge when the subject came up again. Jenny listened to me bumbling for as long as she could stand it and then grabbed the laptop.

‘Let’s get some answers here. How big’s the Macadamia gene pool? How many species in the genus?’

‘Two,’ I said confidently. Jenny did a spot of googling.

‘Wikipedia says there are nine species in the genus
Macadamia
.’

‘According to whom?’

‘It doesn’t say.’

‘Does he, she or it name them?’

‘Hm. Seven from eastern Australia, one from New Caledonia and one from Sulawesi.’

‘That’s easy. There was a group of proteaceous plants growing in north Queensland that got lumped in with the Macadamias but they’ve been lumped out again. The one from Sulawesi was
Macadamia hildebrandii
. They’ve all been relocated in the genus
Lasjia
.’ I pronounced it to rhyme with ‘mass jeer’.

‘Never heard of it.’

‘Me either. I’m not even sure how to say it. It’s a made-up name to honour the Australian expert on the Proteaceae, L. A. S. Johnson. Have a look at APNI.’

APNI is the on-line Australian Plant Name Index. As Queensland has yet to publish a state Flora, and the 3-volume 1986
Flora of South-Eastern Queensland
by T. E. Stanley and E. M. Ross is both out of date and out of print, we tend to consult APNI in the first instance.

Jenny’s fingers skated over the mouse-pad.

‘Sure enough, five one-time Macadamias are now in the genus
Lasjia
:
Macadamia claudiensis
,
M. whelanii
,
M. grandis
,
M. erecta
, and
M. hildebrandii
.’ (She might have added four more:
M. praealta
is now
Floydia praealta
,
M. youngiana Triunia youngiana
,
M. angustifolia Virotia angustifolia
,
M. heyana Catalepidia heyana
.)

‘Cross-check with Tropicos.’

‘What’s that?’

‘The data base of the Missouri Botanical Garden.’

Jenny did. I could hear her growling in her throat.

‘What a mess. Thirteen species listed and no sign that the taxonomy has been revised.’

‘That may be because they don’t accept the revision.’

As a proper scientist who works on the pharmacology of brain function, Jenny was distinctly unimpressed with the mare’s nest that is botany.

‘The sooner they find an objective way of identifying plants the better. This is hopeless.’

I couldn’t disagree, even though I would miss the barminess of the binomials once barcodes had taken their place. Given the bossiness of the Australian academic establishment, use of the binomials will probably be banned once a barcode system is adopted.

The Tropicos list included four species that have now been classified as belonging to another new genus called
Virotia
, plus two of the five that are now
Lasjia
, and two mysteries,
M. francii
and
M. alticola
. ‘
Macadamia alticola
’ was first called that by René Paul Capuron, who found it 1,600 metres up in the forest of Ambohitantely on the island of Madagascar, where he had spent a good deal of his life studying the tree flora (Capuron, 370). When Lawrie Johnson and Barbara Briggs examined the type specimen, they soon realised that it was not a Macadamia but a new genus that they called
Malagasia
, after the island itself (Johnson and Briggs, 1975, 175).

The more we foraged, the more Macadamias we found. All but four had been reidentified as something else.

After some more rambling round the net, Jenny stood up and stretched.

‘I get it. Austin Mast at Florida State University got an award in 2005 to run a research programme with Peter Weston and Greg Jordan in Oz and David Cantrill in Sweden where they work on a phylogeny for the Grevilloideae section of the Proteaceae using nuclear and chloroplast gene sequencing. The idea was to track the breaking up of Gondwana by tracking the genetic relationships between members of the group. They published their results in December 2007. Apparently it went a bit pear-shaped.’