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.



    Tuesday, 12 August 2014

    From mangroves to mountains, without either (yet)


    The staff, Friends and many supporters of the Gold Coast Regional Botanic Gardens will, in time, establish a mangrove grove in Lake Rosser as part of their grand plan to express every kind of vegetation from the Gold Coast to the green hills nearby. The lagoon at the other end of the gardens, pictured here, is already showing off some distinctive local plants, as well as an unwanted fern in the form of a Salvinia carpeting the water surface.

    Lake Rosser, on the other hand, is an area 'ripe' for botanical improvement. You can see it this next picture, with some typical Gold Coast housing at the back. What you can't see is the 1.5 kilometre pathway behind me, already showing off a colourful butterfly garden and whispering she-oak forest (featured in the photographs at the end of this post).


    For a botanic garden built on a coastal plain, creating a mountain is a tall order. Still, the gardens have a couple of vantage points, one with a demountable housing the Friends' offices and shop, plus a new coffee cart that I can recommend for a cup of Mexican, fair-trade beans turned into a very nice double ristretto (with a dash of hot milk…).


    I was on the Gold Coast for the weekend as keynote speaker for the national conference of the Australian Friends of Botanic Gardens. There were about 100 of us there, from botanic gardens all over the country (although interestingly only two representatives from New South Wales, my friends the Fletchers from Orange).

    The conference was a lovely mix of the practical (e.g. how to build a herbarium), the new (e.g. apps) and the whimsical (ah, that must be my talk on a new set of seasons for Australia). You can see the full program here.

    The Gold Coast Regional Botanic Gardens is plonk in the middle of the extensive Gold Coast city, about six kilometres from the surf. It was opened in 2003 and I (first and) last visited in 2008, to plant a tree in what is now called the Curator’s Walk. I couldn’t remember which was my tree so got photographed next to a healthy looking Syzygium moorei which, as luck would have it (as confirmed by a photograph sent to me last night by Alan Donaldson; that's me with the shovel, and Lesley Kirby and Steve Forbes enjoying the incongruity of the situation) seems to have been the species and perhaps specimen I planted. Although I should add that other pictures show a bit of shared responsibility in the planting...

    2014
     2008

    Kate Heffernan (prominent at the conference) and fellow plant enthusiasts formed the Friends of the Gold Coast Regional Botanic Gardens in 1989. This group is very much the driving force behind the garden, although they now have the support of a part-time curator funded by the Council, Liz Caddock (with a PhD from the Jodrell Laboratory at Royal Botanic Gardens Kew no less). Together they are bringing to life the landscape plan of Lawrie Smith, creative mind behind nearly all the regional botanic gardens as well as a couple in New South Wales (and even some later additions to the Singapore Botanic Gardens).

    Only 11 years since their first community planting day the garden already contains plenty of fascinating species and interesting collections. The plans include an expansion of the local flora collections and an even greater emphasis on plants used by local Aboriginal communities. On the day I arrived there were a few hundred school students participating in the Drumley Walk, a project linked to fostering the local Yugambeh language, sure to feature strongly in the next Commonwealth Games (our conference started with the national anthem sung in Yugambeh and then English).


    There are some trees they don’t want, like these Camphor Laurels, remnants of the farmland hedges (that’s why they are multi-stemmed from low down – lots of heavy pruning) and an environmental weed up this way. But mostly it’s about planting. Every Arbor Day, in particular, community groups gather to create yet another botanic display.

    At 31 hectares and with such an enthusiastic Friends group - although the conference proves, if proof was needed, that similarly passionate groups exist all over Australia (and I know from experience that the lack of Friends from Sydney's Royal Botanic Gardens doesn’t reflect any lack of passion or enthusiasm there) – there is the potential to do some great things here. Already it’s a must-see on the Queensland Botanic Trail.

    Here a few pictures from the Mangrove to Mountains trail - the butterfly garden and the she-oak forest - and two snaps of a Brachychiton in flower and fruit. And no, I don't know whether this species is from coast or the mountains, or somewhere entirely different. I haven't even tried to identify it...too busy enjoying the botanic gardens.





    Tuesday, 5 August 2014

    Winter rose trades petals for cones of honey


    Most hellebore flowers have no petals. My wife Lynda discovered this in her weekly botanical art class with Mali Moir run by the Friends of the Royal Botanic Gardens.

    When you paint a flower, with accuracy, you tend to pick up details like this. To be fair Lynda had to seek professional advice on whether the ring of coloured flaps around the crowded stamens (the male bits) and nectaries were petals, sepals (the next layer outside) or perhaps bracts. My professional advice was that yes they most certainly were one of those and we should find some reliable reference.

    The hellebore, or Winter Rose, is in the buttercup family, Ranunculaceae, so around the cluster of stamens you would expect to find petals. Instead there are a these odd cone-like structures.


    This ring of nectaries, or honey leaves, is found in all wild species today. They resemble olympic torches or, as colleague Neville Walsh prefers it, ice-cream cones, and they contain sweet, bee-attracting, nectar. Here are a few more.


    In the original hellebore flower these cones (or torches) were presumably petals because they are relatively easy to convert back to a pretty layer or two of these according to the owner of Post Office Farm Nursery in Woodend, Peter Leigh. His half hour tour of the nursery on the weekend was fascinating and revealed lots of variation in the nectary-come-petals, including these so-called anemone flowered hellebores which seem to be undecided.



    To propagate hellebores you either divide the plant or collect seed. Dividing is slow and doesn't give you many plants. Seed can result in unwanted variability. So Peter Leigh hand pollinates plants in a bee-free shade house. This way he can keep the cultivars he likes as well as experiment a little.



    It's a slow business. These seedlings only emerge nine months or so after the seed has been sown. The seed has to be sown fresh and then kept moist for that entire time. It will be another two years before they flower. Like this Helleborus argutifolius from Corsica, with nectaries as you can see.



    Nearly all hellebores come from Europe and nearby Asia. There aren't many of them, maybe 17 species in total. There is this (next picture) single species from China, Helleborus thibetanus, from high mountains in the central part of the country. Unusually the plants are deciduous, in that they lose their leaves and become dormant after flowering. Although discovered by botanists and named in the nineteenth century this species only made it into cultivation in the UK in 1991 and presumably into Australia soon after.



    To answer the original question, the big showy flaps on these flowers are sepals, the layer usually found outside the petals and often green in colour. In the hellebores the sepals do all the attracting of pollinators, along with cones full of lovely nectar. Except of course when breeders like Peter revert the nectaries back to petals.

    To finish, a couple of hellebore flowers showing off their colourful sepals, one with cones, one without. The latter, you'll notice, has yellow petals that you and I would now most likely mistake for sepals.


    Tuesday, 29 July 2014

    Called for not calling a cabbage a cabbage


    As Ben Shewry from Australia's top restaurant, Attica,  finished answering my question about foraging I swung around to survey Ripponlea's vegetable garden, tended by Ben and his kitchen crew. Lots of colourful Brassicaceae, I said, among other things.

    The interview went well, at least from my perspective. Ben was loquacious and learned and when distilled to five minutes or made a nice little outdoor element to a pilot I'm working on (with Jim Fogarty) for Radio National, RN. More of that in a later post, if by chance it gets up.

    When I returned to the studio with my recordings I listened through with Amanda Smith, our producer for the pilot. Amanda was positive but looked askew when we hit the word 'brassicaceae'. What's a brassicaceae she asked. Good question I said, confessing that after telling all my guests to avoid botanical names unless explained I had slipped up on this one.


    Cabbages and the like is what I told Amanda. Brussels Sprouts (photographed here are a bunch from the Farmer's Market at Abbotsford Abbey), broccoli, cauliflower, mustard and, yes, cabbage. But also Arabidopsis the experimental plant of choice by many scientists, the weedy cresses and plain but threatened species such as Ballantinia antipoda, Southern Shepherd's Purse, on Mount Alexander (and pictured below in our nursery at Royal Botanic Gardens Melbourne).


    Much to my own surprise I like most Brassicaceae and I've featured quite a few in my blog. I got to know them when I was writing taxonomic accounts for the Flora of Victoria, growing to love their tiny cruciate petals (the old family name was Cruciferae, after the cross-shaped arrangement of four petals).

    The current wonder vegetable Kale is a Brassicaceae. It's a cultivated form of Brassica oleracea, as are Brussels Sprout, cabbage, broccoli and cauliflower. All variations on a theme.

    Brassicaceae, as you've gathered from the membership list, are a big part of the human diet. They are generally considered to be the healthy part of a meal, carrying plenty of vitamins, fiber and minerals. DNA repairing chemicals, free radical protection and antioxidants are all ascribed to Brassicaceae. Sure some folks don't like the taste of them, but we all know they are good for us.

    Stretching out in front of me at Ripponlea were some colourful cabbages. That's what I should have said, not Brassicaceae. Or better still, both. Then I could have educated, and entertained. Amanda Smith didn't really mind and in the final edit, if it ever goes to air, you'll hear me talk of Brassicaceae and other things.

    Tim Entwisle

    Tuesday, 22 July 2014

    Pea flower more canary than butterfly




    This is a canary, and these are the flowers of the Canary-bird Bush.


    You won't get the two confused but you can see, perhaps, the point of similarity in colour and bearing. With flowers this large and showy, a bright little bird is not a bad analogy. For a plant botherer like me you can't help but wonder anew at the form and function of a pea flower, often described as papillionate, or butterfly-like.

    Some flowers of the pea family are more like butterflies than this one but it has the typical bilateral symmetry, where there is only one way you can slice it to create two identical (but mirrored) bits. We call this zygomorphic.

    The big petal sticking out the top is commonly called the standard, or sometimes banner, and less commonly these days (unless you read obscure taxonomic journal articles) the vexillum. It's the part that when broad and notched in the middle (in other genera) can look a little like butterfly wings. Below this is the keel, formed by two narrow petals at least partly fused together along their length, flanked by two wing petals. The reproductive goodies are gathered together inside the keel.


    In the flowers of this Crotalaria agatiflora, the Canary-bird Bush, from the highlands of tropical east Africa (and the Grey Garden in Melbourne's Royal Botanic Gardens) the standard is spade-shaped, the wings quite small and like little tongues poking out the side of the brown tipped keel.

    The Canary-bird Bush is just one of 700 or so species of Crotalaria, most of them native to Africa. Crotalaria is a member of the Papilionoideae subfamily of Fabaceae (or in some systems, simply the Fabaceae with the other subfamilies including cassias and wattles pulled up to family level).

    As I said, the flowers are zygomorphic, as are most in the subfamily. There are a only a few with more complicated symmetry, e.g. the asymmetrical Vigna caracalla, the Snail or Corkscrew Vine (its flowers have weird curly bits but you'd probably still recognise these as variations on the papilionoid theme).

    Pollination in papillionate flowers is usually 'brush type', where the male and female parts emerge from the keel in response to the insect rummaging inside the flower for nectar. In all my pictures the stamens and styles (male and female bits respectively) are well hidden, waiting perhaps forlornly in Australia for butterflies and bees heavy enough to part the keel.

    The colour, the drama, and the size are all about attracting the pollinator and presumably guiding it to the bits that matter. I'm not sure about the dark brown spur on the keel but I bet that guides the insects in some way so that they assist the plant in its pollination.


    Finally, the source of these flowers, our Crotalaria bush, a green bush with yellowish green flowers, nestled among grey plants in the Grey Garden. We also grow it in a couple of other places in the Royal Botanic Gardens. Up north, and even in far eastern Victoria, you might find it growing weedy in the bush: it's naturalised widely in the Southern Hemisphere, even in cooler countries such as New Zealand. So beware and be careful if you grow it, but do enjoy its papillionate, or canary-like, floral display.

    Images all from the Grey Garden in Melbourne's Royal Botanic Gardens, except for the Canary, which is borrowed from LafeberVet.com