Tuesday, 28 October 2014

Western Australian Christmas Tree not so sweet in the east


Two months ago I was in the Australian Garden at Royal Botanic Gardens Cranbourne - part of mighty Royal Botanic Gardens Melbourne empire - with Steve Hopper and his wife Chris. Steve is a Professor at the University of Western Australia and previously Director of Perth's Kings Park and Botanic Gardens as well as that little old garden in London, Royal Botanic Gardens Kew.

So he knows something about plants and in particular the plants of Western Australia. I was keen to show him Howson Hill, part of the second stage of the Australian Garden. Steve had been there for the opening of Stage One but hadn't seen the recent developments.

He was impressed by it all but enjoyed seeing Western Australian plants thriving on Howson Hill, including some he had named himself. One he certainly hadn't named, but I wanted him to see was our Western Australian Christmas Tree, Nuytsia floribunda, the largest (semi)parasitic plant on Earth.

Nuytsia in in the mistletoe family, Loranthaceae, and has only one species which occurs naturally in the south-eastern corner of Western Australia. It gets to 10 metres tall, and is covered in yellowy orange flowers around Christmas time.

This is one amazing plant. It's a semi-parasite (that is, it also has green leaves and does some of its own food production) that connects to the roots of any nearby plant. It's not choosy - annuals or perennials, grasses or shrubs, plants or powerlines... To get inside the root of the plant it cuts half way through and then penetrate into the food and water transport system within. Steve said that in Western Australia Nuytsia has been known to black-out houses when it cuts through an underground power-line instead of a root.


This Western Australian Christmas Tree at Cranbourne is one of the first plantings on the site, moved there not long after it was purchased, in the 1970s. Thanks to the horticultural expertise of Warren Worboys, Curator of Horticulture, seedlings were germinated and attached to willing hosts. Three were planted out at Cranbourne, only one surviving to maturity.

There are very few examples of this species growing in cultivation, particularly in the east. We promote ours as the most southerly specimen in the world, and sometimes as the most easterly.  Steve Hopper reminded me that one of the early Directors in Sydney, grew it to at least cotyledon stage (that is, with seed leaves), discovering to his surprise that it had three or four of the damn things. It's a 'dicotyledon' which tells you how many cotyledons you should expect (usually) - two!


On our visit, in late August it was exuding this transparent to amber coloured resin. With a texture, and as it turns out taste, like silicon sealant, there were half a dozen 3-5 cm in diameter blobs (about the size of a fat cicada) hanging from the trunk. Steve was familiar with them from Western Australia and said the the Noongar, the Aboriginal people living near Perth, ate them as a sweet.

As we tasted a small sample, we regaled each other (and Chris) with stories of how many bushfoods have to be pretreated in some way to remove poisons. In a botanic garden one must also have the permission of someone like the Director and Chief Executive to sample and eat any plant material. Lucky I was on hand.


As you can perhaps surmise from this picture of Steve sampling a fragment, it wasn't sweet. In fact it wasn't anything. Just like I imagine silicon sealant would taste without the drying spirit added to it. We didn't die or fall ill. We just didn't want to eat any more. Checking later on the internet I find it reported as a 'sweet gum', eaten raw by people indigenous to its natural area.

Clearly we need some help from Aboriginal people who know more about this plant. Of course it may be that while proud of our achievement, growing Nuytsia at its most southerly and easterly limit isn't good for the production a sweet gum.

Tuesday, 21 October 2014

With Don Watson in search of lost Mallee (Plant Portrait X*)


I was born in the Nhill Hospital but because my parents moved on when I was only two, I can't really say I lived in any remembered way in Nhill.

Still, I experienced Victoria's Mallee as a child through regular visits to my cousins' house, a few miles (as it was then) out of Hopetoun. After my father died when I was six, and we had moved to Euroa via Wangaratta, my two younger brothers and I spent even more time there, enjoying an odd mix of dusty, anarchic adventure and access to a vast library of mostly humorous English writing, all in paperbacks.

Don Watson also spent time in the mallee, but mostly as a contemplative adult, long after his childhood in Gippsland. I've just finished reading his The Bush: Travels in the Heart of Australia and there is plenty in the book that resonates and causes me to reminisce.

Book Cover: The Bush

Watson's family, like many who farm, say they come from The Bush. I've always said I come The Country. My rural life was in country towns, the son of teachers. Don Watson's was from a farm, or two. In his book Watson travels from his childhood to his penultimate home in Mount Macedon (he has recently moved back to the city), via much of eastern Australia.

Watson's description of the Mallee, in particular, rings true. The mice plagues, I remember well. He mentions tails dangling from cracks in the ceiling (one of the more savoury stories amid the mass slaughter of these rodents). I remember lying awake at night waiting for them to drop to the floor and during the day lifting up sheets of corrugated iron to shriek in horror/excitement at the seething mass of whiskers and tails beneath.

And Don Watson marvels, as he should, at the plans of the 80-year old Bosisto company to increase their eucalypt oil production in the Bendigo whipstick, just east of the Mallee, to not only out-compete China (today's leading producer of eucalypt oil) but to one day produce a substitute to petroleum. (Bosisto's fascinating story was also featured on a recent episode of ABC's Landline.)

Mostly, though, the Mallee is and was about wheat and sky. One of my stronger childhood memories is waiting on the station at Sea Lake, with no other soul around that I remember, watching the sun rise and then the dust from my uncle's car grow closer, all in relative silence before I was enveloped into the noise of the Hopetoun household.

I also remember sitting on the veranda of a house not far from my cousin's place, with farm junk scattered around, watching a sunset I think. It's often about watching, and about the softer edges of the day, when it's not so hot and not so harsh.


In the early years I would be viewing the Mallee from a caravan placed somewhat arbitrarily in the one or two hectare, square property plonked in the middle of the wheat fields (not, I should add, in the middle of this road somewhere in Victoria - this is clearly just a toilet stop for me). My uncle was a lawyer with offices in various of the local towns. He had a huge, and to his children greatly wearing, knack for funny stories and he liked to grow Australian plants in a fairly haphazard but courageous style,

Not every one likes the mallee. Watson says that the first Director of Melbourne's Botanic Gardens, Ferdinand von Mueller, bypassed it on his way to collect plants further north in Australia.

The book is about much more than the Mallee. It reaches from the soggy forests of Gippsland to the lonely interior of the continent. From Aboriginal care to European distrust. I like that Don Watson sees his later search for imperfections (in life and language we presume) as coming from being taught to 'spot the thistle in the daffodils'. This kind of upbringing, he muses, make you see faults before loveliness.

It's a meandering story, at times as tangled as the weedy scrub European settlers have allowed to replace the bush they cleared. That's not a bad thing and I have a tendency to stray a little myself. Here, for example, is my uncle's Valiant in which I later learnt to drive (in this picture I am a small boy talking to my mother in the back seat, while my father I suspect is taking the picture). It is parked next to what I presume is Lake Lascelles, just out of Hopetoun, on which my cousins sailed every now and then, when it filled. Or perhaps it is Lake Albacutya further to the west. As Watson notes, like Lake Eyre, these Mallee lakes are remnants of the long departed inland sea.


As you'd expect, Watson's book has some lovely writing, with sparkling sentences and sentiments such as this, describing those in search of Red Ceders in the Big Scrub in the mid-nineteenth century: "We don't know how far they regressed, if at all, but if they are indeed among the progenitors of the national character and values, it might be a calculation worth making."

One of the best is almost lost in a bracketed aside after a story of a boy's lie about checking a windmill leading to the death of a hundred cattle: "Along with birdsong and room to roam, it is one of the privileges of a country childhood to live in permanent fear of a biblical drubbing should one neglect to shut a gate or turn off a tap". That same privilege seeped through to us townies who schooled and played with kids from the farms.

Notes: After writing this I interviewed Don Watson for the radio version of Talking Plants, to run over the Christmas break on ABC Radio National. Turns out he's a keen gardener and, as you'd expect, able to link gardening and plants to the bigger questions in life. (You'll note the images here contain few attractive plants, reflecting accurately my memories of the Mallee.)

Tuesday, 14 October 2014

No great wine escape


Botanical colleague Neville Walsh was wondering, aloud, why you don't see grape vines taking over the Victorian bush. They grow well in many parts of the State, they produce plenty of fruit, and the seed-containing pomice from wine and juice making is often discarded outdoors. Yet there are only a handful of reports of its escape into natural vegetation.

Neville presumed, aloud, that the seed was most likely infertile. My extensive sleuthing on the internet supports this presumption, sort of. Growing grapes deliberately from seed it not easy. It can, according to one experienced grower, take up to three years. Firstly, only a small number of seeds will germinate. It may be that they are mostly infertile but also because they require 'stratification'.

That is the seeds need to be pretreated in some way before they germinate. Only by subjecting them to few months of cold temperatures to trigger the plant to force it's way through the tough seed coat.

According to this same source, Danie, once extracted from the fruit pulp, the seed need two to three months at just above freezing (1-3 degrees C). This alone would make most of Australia unsuitable for colonisation by a rogue grape.

Seed will still take a few weeks to germinate, and there are reports of it taking up to eight. Even after stratification the strike rate is low.

Other people simply recommend sowing the seed and then waiting for three months, presumably in places where temperatures drop a little and help the seed break its dormancy.



This is presumably why Vitus vinifera, the wine grape, is only 'sparingly naturalised' in Victoria. I notice that it's described as full-on naturalised (i.e. established and spreading in the bush) in Western Australia, South Australia and New South Wales (and 'doubtfully naturalised' in Australian Capital Territory).

That summary may over inflate the real situation given that in New South Wales, for example, the distribution based on vouchered (herbarium) records is 'occasionally naturalised' and there are only three records on the PlantBank database. How close these are to domesticated vines I don't know but the dots seem to be in established wine growing regions (e.g. Hunter Valley).

There are more dots (on the map) in Western Australia but mostly hugging around Perth with just a few in the Margaret River area. In South Australia there are 18 records, scattered around the south-west wine growing areas.

I don't get the impression it's a sleeper weed, with the potential to break out and rampage through our native vegetation. But if the climate changes to its advantage and we are careless in where we toss our pomice, who knows.

Images: The vineyard at the top is beautiful Tarrawarra in the Yarra Valley, where I saw no evidence of escaping wine vines. The other picture is of a single plant, one of the oldest and biggest in the world, growing inside at Hampton Court Palace and therefore unlikely to escape.

Tuesday, 7 October 2014

Close encounters with the Teddybear Cholla


The sign was clear. Don't touch. Don't even think about touching the Cylindropuntia bigelovii, even though its common name is the Teddybear Cholla (pronounced choy-yah).

So I picked up a small piece. Swore. Flicked it onto my foot where it attached itself securely to the front of my shoe. I eventually managed to scrape it off on a rock and then break the remaining spines back to the rubber in my shoe. This was two weeks ago, while in the Joshua Tree National Park south-east of Los Angeles. The spiny remnants reside in my shoe still today.


Back in the desert as temperatures hit 96 degrees F (around 36 degrees C) in what is quite appropriately called the Cactus Garden, Lynda mumbled something about signs and kids. I licked my wounds.

The Teddybear Cholla is by far the most common species of cactus in the park and pretty successful at getting around. It's a close relative of the prickly pear and in fact used to be included in the same genus, Opuntia. The most obvious difference is that the chollas (there are others in this group) have cylindrical stems (i.e. the green blades that make up most cacti) while the prickly pears are flattened ones.

The spines are also different, as I experienced. Many opuntias (as I can also attest) have clumps of tiny 'glochids' which look innocuous but persist and irritate long after any contact with the cactus. The chollas have pretty obviously aggressive spines and you'd be an idiot to even touch them.

The Teddybear Cholla is also called the Jumping Cactus due to its propensity to find its way from the ground to some part of our body. It can seem at times like it jumps at you. All these detached bits and pieces readily root and settle in as new plants, sometimes after being transported rather long distances (e.g. to Australia; although I should say that personally I may have carried fragments of spines, but not flesh of the cactus).


I gather the easiest way to remove the reverse-barbed spine from your skin is to use a comb and to 'quickly jerk it away'. I wasn't carrying a comb and in any case, due to the force required I gather there is also a risk it flies straight into your companion, making a fresh connection.

A mature specimen is about one to two metres tall, with the base becoming trunk like with age as lower branches die and fall off. The spines cover pretty much the entire surface of the plant, which must make it difficult for sunlight to reach the green photosynthetic tissue. Presumably protection from desiccation and predation are more important.


Young spines are yellow. Old ones black. Yellow-green flowers appear in spring with the fruits, as illustrated here from mid-autumn, mostly without fertile seeds. It does nicely without resorting to sexual reproduction it seems. In fact according to the Arizona-Sonora Desert Museum, many plants have three rather than two sets of chromosomes, and are completely sterile. These sterile plants can still cover up to two square miles desert excluding nearly all other plants.

This species is common in the Mohave Desert and hotter parts of the Sonoran Desert, both of which intersect in the Joshua Tree National Park. And I can't really post about the Joshua Tree National Park without a picture of the striking Joshua Tree (Yucca brevifolia) so here it is!


Notes: Thanks Lynda for the final picture, and yes I lied when I said my last post was the final one from my US holiday. This one, almost certainly, is. 

Tuesday, 30 September 2014

It's tough at the top of the world's tallest trees


This is the second (and last) of my holiday posts from North America, in this case researched a little before I left Australia. It's a long one, pictorially, due to the elongated plant subject. I've traveled across the country (by plane), from giant topiary in New York last week to giant trees in California today. From the ridiculous to the sublime.

Back in 2005 when I wrote an article for Nature Australia magazine called 'Size matters', I reported that the world’s tallest plant was a 112.7-metre-high Coast Redwood growing in Humboldt Redwoods National Park, California. I think it still is the tallest but presumably plus or minus a metre or two now. It grows a few hundred kilometres north of where I saw and photographed this Giant Redwood.


Just for the botanical record, the Coast (or Californian) Redwood is Sequoia sempervirens, the only species in this genus. A closely related and equally 'big tree' is called the Giant Redwood, Sequiadendron giganteum, and it is also the only species in its genus.

Despite its common and botanical names, the Giant Redwood doesn't grow quite as tall as the Coast Redwood, but it achieves bigger bulk - that is, the volume of its trunk is the largest in the world (the Montezuma Cypress, Taxodium mucronutum, in Mexico has the largest girth - over 15 metres in diameter). Both Redwood species frequently top 100 metres in height but the tallest conifer ever recorded was a 126-metre Douglas Fir, Pseudotsuga menziesii.

All these conifers are clearly big trees. Flowering trees, like our gums, also grow tall of course. Although there are claims of Mountain Ashes (Eucalyptus regnans) in southern Australia being over 120 metres, the tallest ever measured officially was 107 metres. Today the tallest living specimen is I think still a 97 m tree called ‘Icarus Dream’ in the Styx Valley in Tasmania. It's quite possible this tree will reach 100 m over the next few decades.

But don't expect it, or even the Coast Redwood, to ever get to 130 metres. As I reported back in 2005, what limits their size is a plumbing problem: how do you get water from the ground to a leaf fluttering 100 or so metres above?

George Koch from Northern Arizona University, and his associates, reckon we'll never see a redwood over 130 meteres tall. They climbed the world’s tallest trees to measure water potential and photosynthesis in the highest branches, followed by more detailed analysis of leaves transported back to the laboratory. Water is drawn up the tree (what we call transpiration) in a continuous column as it evaporates from leaves into the atmosphere. They found that gravity starts to win out against water cohesion at around 110 metres.


It turns out the leaves most distant from the base of a gigantic Redwood such as this one are under extreme water stress, and their small size and low photosynthetic rates may be due to the plant closing some of its breathing pores (stomata). This would not only retain precious water, but also slow down the rate of water transport through the plant, reducing the possibility of deadly air bubbles being formed—a break in the water chain would be permanent and mean death for a lofty limb.

They also found that to keep one of these big trees alive and transpiring healthily, the surrounding forest must remain intact to maintain high moisture levels and buffer the trees against storm damage. So if we want to see big trees in California, or in Australia, look after the forests that surround them. The recent drought in California is putting some of these big trees under additional stress, so doing what we can to reduce the severity and impact of climate change will also help our botanical giants survive.


Images: All from Mariposa Grove, at the southern end of Yosemite, taken last Wednesday (I'm now back on Melbourne). Lynda very kindly photographed the top picture.

Tuesday, 23 September 2014

Toy Topiary keeping an eye on the Big Apple


Last week I visited New York's (rather than Malvern East's) Central Park, which was as incongruous and inviting as I expected, although more so 70 floors up from the Rockefeller Centre. Instead of showing you lots of photographs of that striking green edge to New York's skyscrapers I give you this floral horse-dinosaur, by Jeff Koons.



Slit-Rocker has grown in Avignon, Versailles and Basil. Since June it has bloomed behind Paul Manship's gold Prometheus sculpture in front of the GE Building at 30 Rockefeller Place (and I can't help but hum the theme song from the TV show 30 Rock every time I type or say that).


Apparently there are 50,000 petunias, geraniums, begonias, fuchsias, impatiens and marigolds covering this 11 metre tall fusion of half a toy pony head and half a toy dinasaur head. Although watered by an internal irrigation system Koons says one of the things he is intrigued by is giving up control and seeing what happens. 'It's in nature's hands' he says.

In case you are interested, this is part of the infrastructure behind the flowers, in a photograph I took a few days later, after all the flowers had been removed.


According to Plantcurator.com, to keep one of his previous flora sculptures (Puppy) alive, if not kicking, a gardener attended to it weekly removing weeds, replacing weak plants and giving extra water if needed.


These nature's gardeners may be tending the plants, or perhaps starting its deconstruction as the square is readied for its next big plant exhibit, the annual Christmas Tree. There is also a Koons' retrospective at the Whitney Museum of American Art, running until mid-October, but I was museumed out after visiting the Met, the Guggenheim and MOMA.


Given there is not a lot more I can say about this without a) sounding pretentious, b) giving away my lack of knowledge of modern art and artists or c) doing more research, let me finish with Central Park, from 30 Rockefeller Plaza. The border of the buildings and park is Central Park West, a street Bob Carr in his Diary of a Foreign Minister calls the world's most beautiful (and anyone who has read the book, or knows Bob, will be aware he is not a man prone to hyperbole or hubris).


Or, you can finish with a lovely plate featuring Koons' floral half pony, half dinasaur. You choose...


Tuesday, 16 September 2014

Careful, they might hear you


On my first visit to China, ten years ago, to the Xishuangbanna Tropical Botanical Garden, I was intrigued by this plant Codariocalyx motorius. According to my Chinese colleagues it responded to singing by wiggling its stipules, small flaps at the base of its leaves.

As I mentioned in a post a few years ago, the plant failed to perform. It may have been our fault. Rather than sing, a mobile phone ring tone was used to entice the Dancing Plant, as it was called, to dance. I assumed it was probably the vibrations caused by particular noises that caused the response, when and if it did respond.

Now I can report that plants can 'hear' insects munching on their leaves. This discovery by scientists at Missouri University comes close on the heals of a revival in interest in plants communicating with one another (extending the sharing of genetic material). The distinction between plants and animals becomes increasingly blurry.

This cabbage butterfly caterpillar munches on an Arabidopsis leaf adjacent to  a leaf where a piece of reflective tape bounces back a laser beam used to detect the vibrations created by its chewing. Roger Meissen/Bond LSC

The plant with ears is the popular experimental mustard plant or cress, Arabidopsis, and the noisy eater the caterpillar of the Cabbage Butterfly. Vibrations from the caterpillar's eating travel through the leaf and stems, triggering chemical defenses by the plant. Wind and other vibrations applied to the plant don't cause any reaction - it's all to do the frequency of the caterpillar's crunch.

Whether you could really describe this as the plant hearing noise is of course a moot point. Although sounds are usually defined as vibrations traveling through air and received (heard) by something else. That fits pretty well what is going on in the mustard-caterpillar interaction.

As you'd expect, these sounds are very quiet. Microphones can't be used due to the small size of the leaves and the caterpillar's mouth, but a piece of reflective tape nearby (see attached to the leaf next to the white caterpillar above) reflects a laser beam which gets disturbed by the (minutely) noisy eating. This response can be amplified to a speaker so that we can hear the caterpillar's crunching.

In response to this quiet racket, the plant produces a number of defensive chemicals, one of which is called glucosinolate. Glucosinolate makes mustards spicy, may cure cancer in humans, gives red wine its colour and making chocolate healthy. For a caterpillar, however, it is repellent.

Playing the chewing noise back to plants caused higher levels of glucosinolate to be produced. Other sounds and frequencies had no effect so it isn't just the leaf shaking about that causes this response. 

Returning to my Dancing Plant, the researchers say that “The field is somewhat haunted by its history of playing music to plants . That sort of stimulus is so divorced from the natural ecology of plants that it’s very difficult to interpret any plant responses.” 


I suspect they are referring to people suggesting that playing music to plants makes them 'happy' and grow better, as featured in the book, The Secret Life of Plants. When such responses are detected (not often in experimental situations) it is most usually attributed to increased carbon dioxide from humans exhaling nearby or perhaps air movement encouraging greater gas exchange into and out of the leaf.

For a more learned summary of research into what are more properly called 'acoustic emissions' from plants, see Monica Gagliano's (from the University of Western Australia) 2012 summary in Behavioral Ecology. Gagliano concludes that more and more we find that plants 'highly sensitive organisms that perceive, assess, interact, and even facilitate each other by actively acquiring information from their environment'. She says they effectively 'cry for help' when they respond like the cress does to the caterpillar and that there is likely to be more to discover in this controversial but fascinating area of plant biology.

Next up for the Missouri team is to find out whether other plants respond in similar ways and what it is precisely in the vibration, or sound, that triggers the plant response. It's nice to think that plants might do more than dance in response to niggling noises.

Notes: the image of the caterpillar on the Arabidopsis comes from the Decoding Science website, and the idea for the story from colleague Peter Symes.

Tuesday, 9 September 2014

Fungal farm to wormy wood: the ambrosia story


The original Wormy Chestnut was indeed a chestnut, scarred by worms. It was an American Chestnut, Castanea dentata, killed by chestnut blight then chewed by insects that left holes and discoloured the wood while they remained standing.

Because American Chestnut was almost wiped out by the early twentieth century blight, the wood became rare and valuable.

Australian Wormy Chestnut seems to be a mix of East Gippsland eucalypts, such as Eucalyptus obliqua, Eucalyptus sieberi and Eucalyptus fastigata. One of the companies selling it says it is "distressed by Mother Nature", which another company describes as the (attractive) ravages of "fire, ambrosia beetle, pin holes and squiggly worm marks".


The ambrosia beetle is kind of weevil. They are also called pin-hole borers, but not the ones responsible for the neatly drilled holes in old furniture (and the dust that they toss out of the hole). The ambrosia borers like 'green' wood, preferably freshly felled.

The beetle bores a hole into the wood to lay its eggs, and carries with it the spores of  the ambrosia fungus. The spores germinate, the fungus grows, the egg hatches, the larvae eat the fungus. The parent beetle often dies, conveniently, at the top of the tunnel, blocking it from predators and keeping the rain out.

By the time the wood is turned into flooring planks the beetle, it's larvae and the fungus are long gone. Or at least their remains are well dead. The fungus usually stains the wood, leaving a distinctive dark colouration, part of the attractiveness of the final wood product it seems.

representative image of taxa

The wonderfully named Austroplatypus incompertus (meaning something like the poorly-known southern flat-foot) likes trees burnt in bushfires, or similarly injured, and it produces 'extensive gallery systems in one plane only'. The plane, is horizontal, in a standing tree, meaning that the timber can easily fracture at an area of activity.

There is at least one other species of ambrosia beetle in these forests, the Mountain Pinhold Borer, Platypus subgranosus.  In case you are wondering, and I certainly was, the reason the platypus has the genus name Ornithorhynchus rather that Platypus is because this little fella, or at least one of its relatives, was named first.

But enough of beetles, this is a plant (and fungal, and algal...) blog! I bet you are wondering about the ambrosia fungus that colours up the Australian Wormy Chestnut wood so appealingly. There is a whole website devoted to the endearing relationship between beetle and fungus. And this (from the Ambrosia Symbiosis site) may, or may not be, the fungus...


The fungi associated with the ambrosia beetles are a mixed bag, and not all part of a single taxonomic group. This one is a Fusarium, a genus including lots of economically and environmentally important pathogens. There are also filament-forming yeasts and the helpfully named Ambrosiella.

Mostly the fungi can't survive without their ambrosia beetle overlords, but at least some of the Fusarium stock or crop (depending on your perspective, but do remember that fungi are more closely related to animals than to plants) seem to be able to fend for themselves if necessary.

Most or all of the fungi concerned have foregone sexual reproduction, apparently content with their life of coexistence with ambrosia beetle. Although it's not all peace and harmony. There is evidence of fungal rustling, with smaller beetles drilling holes near larger ones to save the bother of carrying around their own fungi.

So there you have it. A small glimpse into the murky world of the ambrosia symbiosis, as it's called. Beetles, fungi and dead trees combine to create an intriguing ecosystem that we slice up, polish and then walk on.

Image: The top picture is Oscar, a dog, doing tricks on the newly laid Australian Wormy Chestnut floor in the house of my friends Mal and Sandy. The annotated wood panel is from Triton International Woods and the image of the Austroplatypus is from Atlas of Living Australia (the species incompertus was included originally in the genus Platypus)

    Tuesday, 2 September 2014

    Sprinter and Sprummer: Australia's Changing Seasons


    "In all things, saving only in those that are evil, a change is to be feared; even the change of seasons, winds, viands, and humours." Essays by Michel de Montaigne, Book the First, Chapter 43: On Sumptuary Laws (1580; translated by Charles Cotton 1877) 

    * * *

    Minutes, hours, days and months are the way we organise our life – sowing crops, attending job interviews, organising lunch with friends, picking up kids from child care, visiting relatives, playing football, getting our hair cut and so on. Seasons are for noting, celebrating and tracking the changes in the world around us. If we get them wrong we don’t lose our crop, job or children. No-one has responsibility for approving the seasons, and they are not anchored by Greenwich Mean or International Atomic Time. Yet they are part of our inherited culture, part of the ritual of living on Planet Earth. Our responses to seasons – like the seasons themselves, as I shall argue – vary from place to place.

    The definition of a season seems simple enough but, as I argue in my new book Sprinter and Sprummer: Australia's Changing Seasons (available 1 September 2014), it is misunderstood, misinterpreted and misused. Why do we have four seasons? Why should they each take up three months of the year? Indigenous communities have always known that Australia’s climate is more complex than a simple four-season arrangement. Isn’t it time for all Australians to adopt a more realistic, home-grown system?

    When I began this book, in Sydney, I wanted to make two somewhat contradictory points. First, that there is a peak flowering period in most Australian gardens and bushland, and it happens before what we normally call spring. Second, that plants flower all year round, not just in ‘spring’, and I thought I would use the opportunity to feature some of the quirky plants of my local town, and country, Australia.

    Three years ago I moved to England, where many of our cultural traditions including our idea of four neat seasons, each three months long, come from. I gained first-hand experience of ‘true seasons’ and the plants that either define them or respond to them, depending on your perspective. I found that even in their homeland, the four seasons don’t always match the annual cycles of nature. So I expanded the scope of this book to address a more fundamental question about whether seasons are ever really ‘fit for purpose’ and to include seasonal stories of plants from around the world. Perhaps it’s not only Australia that needs a thorough review of its seasons – the definition of ‘seasons’ in other countries also doesn’t always match the reality of nature.

    I don’t want to overstate the case for having a set of good, robust seasons. Seasons, like most natural phenomena, have been part of pagan rituals for millennia. Each season has been given characteristics much like the Signs of the Zodiac, and with as much value. For example, the Greek elements of air, fire, earth and water have been correlated with the seasons spring, summer, autumn and winter respectively. So what? I’ve seen the Myers-Briggs Type Indicators, a personality classification system much loved by modern employers, mapped against seasons. Again, for what purpose? For two thousand years or so in Europe, and at various times elsewhere in the world (and still today in some communities), ill health was thought to be due to an imbalance in the body of blood, phlegm, yellow bile and black bile (the ‘humours’ alluded to by Montaigne). To cure this imbalance, some of the offending humour was purged from the body or a ‘neutralising’ compound was ingested or applied. What sense is there in matching blood with spring, yellow bile with summer and black bile with autumn, as some have done? Phlegm’s link with winter does feel about right, though! But the point is that while climate may affect our mood and behaviour, any seasonal classification is unlikely to assist in clinical diagnosis, life planning or recruitment.

    What I am doing in this book is not new. Aboriginal communities around Australia have for tens of thousands of years recognised two to seven seasons, depending on where they live. Since 1788, all Australians have carried the yoke of four European seasons that make no sense in most parts of the country. We may like them for historical or cultural reasons, or because they are the same throughout the world, but they tell us nothing, and reflect less, of our natural environment. In time-honoured fashion I decided from the safe distance of London that it was time for Australia to reject those seasons, to adopt a system that brings Australians more in tune with their plants and animals; a system to help notice and respond to climate change. So the book took shape. 

    After two years abroad I arrived in Melbourne in early 2013, to experience nine days in a row with temperatures over 30°C in March, a weather record for the city. As you’ll see, this tallies nicely with my preference for a longer summer season in Australia. Living in Sydney, London and now Melbourne again (I had left Melbourne in 1998 to move to Sydney) I’m convinced that the four traditional seasons don’t make sense in southern Australia. My proposal is that we have instead five seasons based on the climatic and biological cycles we observe around us. I start with the origins and theory of the traditional seasonal system – the ‘Vivaldi Option’ – then review the Aboriginal seasonal classifications used across Australia, followed by my five-season proposal. 


    My seasonal year starts with sprinter (August and September), the early Australian spring. That’s when the bushland and our gardens burst into flower. That’s also when that quintessential Australian plant, the wattle, is in peak flowering across Australia. Next is sprummer (October and November), the changeable season, bringing a second wave of flowering. Summer (December to March) should be four months long, extending into March when there are still plenty of fine, warm days. Autumn (April and May) barely registers in Sydney but further south we get good autumn colour on mostly exotic trees, as well as peak fungal fruiting. Winter (June and July) is a short burst of cold weather and a time when the plant world is preparing for the sprinter ahead.

    The 'first' season, sprinter, is an early spring and in my mind a no-brainer. It is easy to recognise and backed up by good observational data. The other four are perhaps more aspirational, concepts to test and probe a little further. Although difficult to define, they are the perfect launch pad for stories about the seasonal triggers and tribulations in the life of a plant (and plant-like creatures). Among other things I cover how plants initiate flowers and leaves, why autumn leaves are coloured and what plants do at night. The final chapter considers climate change and how the seasons are changing whether we like it or not. This leads to speculation on whether any system will be long-lasting and a return to the question of whether seasons should reflect reality. 

    This is not a ‘how to’ book: more of a ‘why not’ one. I want the curiosity that got me thinking about seasons to infect others. That’s why this book extends beyond a simple explication of my new seasons system for Australia. Why it includes the interplay between seasons, people and plants. And why I’m happy to float a few boats for others to board, or sink. This is exactly what a good seasonal system, and if I might add, a good book on seasons, should do. It should make us think, and make us think differently. There are no perfect or correct seasons. I am happy for my seasons to be rigorously debated and tested, and I will be thrilled if through more people observing and monitoring the natural world I have to totally redesign my system. Given there is no legislation governing our seasons and our lives will not suffer if we get it wrong, go for it!

    This book is unashamedly a mix of science, rhetoric and opinion. I hope it’s provocative, fun and from time to time informative. I have drawn inspiration and information from all kinds of places, some of them listed at the end of the book. I’m sceptical by nature but I’ve happily included conjecture and perception alongside peer-reviewed evidence and analysis. There is definitely some hand-waving and passionate persuasion here but my approach and my conviction are scientific. I’m with Thomas Huxley on this: ‘Science is, I believe, nothing but trained and organised common sense …’

    *This post is an edited version of the Introduction in Spinter and Sprummer: Australia's Changing Seasons (2014), available now for $29.95 from CSIRO Publishing. An extended version of this post was broadcast two days ago on ABC Radio National's Ockham's Razor - you can listen via the podcast available on that site.

    Tuesday, 26 August 2014

    The thigmotastic monkey flower


    You must remember the Monkey Hand Tree, well this is the Monkey Flower. In this case the flower is not really evocative of a monkey, or any part of a monkey. It doesn't even appear in any of the lists of 'plants that resemble animals' (yes such lists exist).

    The flower is perhaps more like a theatre mask, the kind you might wear to a masked ball, which is where the botanical name Mimulus comes from (a small 'mimic actor').

    Still, while not living up to its common name entirely, the flower does does have some special powers. You might therefore stretch the analogy and make reference to Saiyūki, a special kind of Monkey...


    Anyway, the special power is thigmotaxis or thigmonasty (or seismonasty if you prefer). This is when you or I, or some other creature or thing, touch a particular part of the plant and it responds in some physical way (thigmo is Greek for 'touch'). Think trigger plant for a particularly dramatic example.

    In the case of Mimulus, the lobes of the female bits (tucked inside the vase part of the flower, and revealed below after I pealed away the petals) close together when to touched. In nature this tends to be the bill or head of a hummingbird which bumps it en route to the nectar below. All going well, pollen from its previous visit to a Mimulus flower sticks to the hairy surface of the lobes before they shut.


    This system means that any pollen it gathers on its beak while foraging in that particular flower won't be deposited on its own receptive female lobes on the way out. You can see how near the pollen are to the (now closed) female lobes in the second dissected flower picture.

    In a fresh flower it takes about two seconds for the lobes to come together. In older flowers, or in the cold, it may take up to 10 seconds. This is pretty quick among those plants that employ this technique. The quickest response time is one second but it can take up to an hour, which seems a little pointless unless you have a particularly enthusiastic hummingbird or other pollinator. Or, it may be achieving some other purpose such as as improving the capture of pollen on the receptive lobes.

    A study by scientists at the University of California on Mimulus aurantiacus found that pollen gently applied led to much slower closing of the lobes - up to one and a half hours - but once there the lobes remained firmly shut for a day or even for the full life of the flower. Touching the lobes caused them to close within seconds but they would reopen a few hours later.

    These scientists concluded that thigmotaxis in this species at least did not help in the capture of pollen or in any way assist with seed set. Their discoveries were consistent with the system inhibiting self-pollination - cross-pollination allows a plant to adapt and change over time, and to produce more robust offspring.

    Thigmotaxis of the female lobes is found only in the snapdragon family Scrophulariaceae and some other closely related families such as the Bignoniaceae and Lentibulariaceae. Once a card-carrying member of the Scrophulariaceae, Mimulus is now included with a group of mostly obscure genera - including a few from Australia such as the non-descript Elacholoma and its single species from inland areas - in the Phrymaceae.

    There are four native Australian species of Mimulus (the Creeping Monkey-flower, Mimulus repens, growing in wetlands around Melbourne)* but most come from North America, with some scattered around other regions of the world. The one photographed here is Mimulus aurantiacus var. puniceus, in its natural habitat straddling the US-Mexico border from southern California to northern Baja California.

    Its common name is, quite legitimately, the Sticky Monkey Flower. Hence I found myself strangely attracted then attached to its flowers as I wandered through our Californian Bed at Melbourne's Royal Botanic Gardens in June.


    *Although at least one of these, Mimulus prostatus, has been moved to the genus Elacholoma [thanks Neville Walsh]. I haven't chased down the taxonomy/nomenclature of the others.

    Tuesday, 19 August 2014

    Tropical plant dreaming (Plant Portrait IX*)


    Botanical glasshouses are a place to dream. As are tea shops. Early in James Joyce's Ulysses, Leopold Bloom stares through a window at a canister of tea from Ceylon, thinking:

    ... The far east. Lovely spot it must be: the garden of the world, big lazy leaves to float about on, cactuses, flowery meads, snaky lianas they call them. Wonder is it like that. Those Cinghalese lobbing about in the sun in dolce far niente, not doing a hand's turn all day. Sleep six months out of twelve. Too hot to quarrel. Influence on the climate. Lethargy. Flowers of Idleness. The air feeds most. Azotes. Hothouse in Botanic Gardens. Sensitive plants. Waterlilies. Petals too tired to. Sleeping sickness in the air. Walk on roseleaves. Imagine trying to eat trip and cowheel …

    Bloom/Joyce is musing on the tropics being the bounteous and slothful garden of the world. Good that a botanic gardens hothouse is mentioned. Joyce presumably had the one at Glasnevin, in Dublin, in mind so my first four images are of that conservatory, taken during a visit in June 2010.

    The Conservatory at Glasnevin is a particular kind of glasshouse, one that is more about content than context. You enter to learn about tropical, and other plants, not to necessarily experience the tropics. This is as much a function of size and budget, as it is of intent - it takes a mighty lot of room and money to recreate even a mock tropical environment inside a house made of glass.

    And there is nothing wrong with displays of this kind. Much of the plant collection in the glasshouses of Kew Gardens, and plenty of other leading botanic gardens around the world, is displayed like this. Visitors learn about particular species and about how plants they eat or grow in their garden once grew in liana ridden forests near the equator (or elsewhere). 



    But even in Glasnevin it's not all plant diversity and straight laced displays. Here is picture deep into the glasshouse, with some tropical atmosphere and context.



    At the other end of the spectrum we have glasshouses that are big on context and, usually quite deliberately, thin on content. I'll take the liberty of repeated two images from earlier posts, the first from South China Botanical Garden in Guangzhou, the other from Gardens by the Bay in Singapore. They are very much about creating an atmosphere and sense of being in a tropical forest. 

    If you look beyond the mist and behind the waterfall, the plant selection is not particularly true to a rainforest of any kind or demonstrating any natural diversity or ecosystem. It's all about the vibe, as we Australians like to say - at least since the line was used with such impact in the film The Castle. The designers of these two glasshouses are quite aware and comfortable with this.























    So.... what about here in Melbourne. Our rather plain and small Tropical House in Melbourne's Royal Botanic Gardens is about content, albeit with a pretty design to bring the best out of the collection. We had someone recently describe it as their favourite place to visit in the city. They liked its dagginess I think. It is quaint and it does have a familiar and evocative feel about it, harking back to simple days. Nothing grand, nothing showy, understated...all the things we like in Australia. But...is that enough. Is it?

    I have grand plans to build a new glasshouse in the Royal Botanic Gardens. I don't want a temple for botanists nor a tropical themed wallpaper. I want context and content. I'd like a place where people could gather and learn, perhaps over one of those great coffees I'm so keen on (a meeting place like no other, with a backdrop like that imagined by Mr Bloom in the Dublin tea shop). But also a place that brings the tropics (or some other place) to life, in all senses of that phrase.

    Somehow this has to fit within the heritage landscape of the Royal Botanic Gardens, adding rather than subtracting from the spectacle (as does Guilfoyle's Volcano). It should also have a minimal impact on the environment through clever heating and cooling. I'm sure our bright minds at the Gardens will come up with a solution that does all this and more. If that 'more' includes the plants Rafflesia and Victoria in bloom, I shall be much pleased.

    Images: for more pictures of the National Botanic Gardens, Glasnevin, see my post on various gardens from Ireland back in 2010. For more on South China Botanical Garden is my 2009 post and Gardens by the Bay in Singapore, my post earlier this year. Below is a bust of the author (of Ulysses, not this post) in the Martello Tower museum at Sandycove, near Dublin.