Sooty mould makes a killer honey

In 1855 Reverend Berkeley remarked on an abundance of black moss in New Zealand. At least this is what the locals called it. More generally it is considered to be one of the sooty moulds or as Berkeley himself would have classified it, a pyrenomycete.

Pyrene is what we call the stone of a fruit, such as an apricot, and many of the pyrenomycetes are rough in texture. The mycetes bit tells us it's a fungus.

Black moss is formed by a collection of barely related fungi that express themselves as a black fibrous coatings on tree trunks. In New Zealand they favour species of Southern Beech, Nothofagus*. That's because these fungi thrive on honeydew, a sweet compound produced by scale insects living on the Beech.

It has been estimated that scale insects live on the trunks and branches of Nothofagus* in a million hectares of the northern half of New Zealand's South Island. Their presence is almost always associated with black moss. Although widespread, the insect and its fungal passenger are patchy in distribution.

A month or so ago, tramping near Wanaka, in the southern half of the South Island, I found this patch. I thought a bush fire had rendered every lichen and moss black until a French tourist explained to me that it was, as everyone at least since Berkeley has known, a fungus. I only saw this one small area, perhaps a few hundred metres square, infected with black moss but it was a memorable and photogenic (if you like to take pictures of black sooty things) display.

Black Moss doesn't seem to harm the plant too much although there is some debate about whether scale insects are helpful or not. A study in 2006 argued that not only do they suck up valuable sugars form the plant, they might also reduce the rate of litter breaking down and releasing much needed nutrients to the soil.

The French tourists also told me that bees feeding off the black moss produce a very expensive kind of honey. It is an acquired tasted they said, in a tone that suggested they hadn't yet acquired it.

There are various honeydew honeys produced around the world. The basic principle is that the bee collects nectar from the exudate of another insect, rather than from a flower. They are sometimes called forest honey or, when the exuding insect lives on a pine, pine honey. These honeys tend to have less glucose and fructose, and more complex sugars and minerals than flower-sourced honeys. And they don't crystallize easily.

But honeydew honey from New Zealand is different. In addition to the insect exudate it contains bits of the black moss (which sounds marginally better than 'bits of the sooty mould'). That may be one reason why it tends to be darker in colour than most other honeys, although its deep colour is more likely due to the bees storing it in darker combs.

Naturally because this honey is relatively rare, expensive and intriguingly produced, it must be good for you, right? Well according to my not entirely unbiased source, it has plenty of oligosaccarides to help you maintain good bacteria in your gut, plenty of antioxidants which everyone seems to want, and a dose of an antibacterial called glucose oxidase (I'm just assumed it kills only bad bacteria).

As yet I haven't tasted any. All the shops seemed to be selling expensive Manuka honey, produced from the flowers of the local teatree, Leptospermum scoparium. The most expensive jars of this condiment contain methylglyoxal which a German scientist swears is antibacterial. There are obviously some nasty bacteria out there and honey, in one form or another, is the way to deal with them.

*Without wishing to worry you too much, a proposal to split Nothofagus into five genera has just been published, meaning the New Zealand species would no longer be Nothofagus but either Lophozonia or Fuscospora.

Volcanic aftermath leads to potatoes and a botanic garden in Geneva (Plant Portrait VI*)

My companion at a dinner last month said it was the volcanic eruption in 1815 that led to the establishment of the Conservatoire et Jardin Botaniques in Geneva. The smoky skies led to six months of starvation across Europe, I thought I heard him say.

The rest was lost in the muffled conversations that I now enjoy in any busy restaurant or function centre. This time it was the town hall of Dunedin, soon after it had been announced that the next Global (World) Botanic Gardens Congress was to be held in Geneva in 2017.

Later, though, as I trawled the remains of my high school European history chronology I couldn't place a volcanic eruption in Europe, in that century, or having any impact on the Napoleonic events around that time. So I did the obvious thing and searched for '1815' and 'volcano' on the closest e-device.

Sure enough, there was a major volcanic eruption in that year. Coincidentally, a recent issue of New Scientist waiting for me in my office when I returned to Melbourne included an article on volcanoes that have altered our climate over the last 70,000 years. The eruption of Mount Tambora, on the island of Sumbawa in Indonesia, in 1815 killed about 71,000 people locally and changed the world climate for the next six months. Europe, it said, had a 'year without a summer'.

That summerless year was the making of the Geneva botanic garden according to my Swiss friend in New Zealand. But why? Some further searching revealed a short backgrounder to the first botanical garden in Geneva by René Sigrist and Patrick Bungener.

In the eighteenth century Geneva was blessed with a number of large private gardens that fulfilled some of the desires we have for botanic gardens. They were full of interesting plants from all over the world, including in the garden of Paul Gaussen, the oldest female ginkgo in Europe. Until the end of that century, it seems, this specimen was the source of all ginkgos kept in the gardens of mainland Europe.

I've told before the story of this ginkgo growing in the Montpellier's botanic garden, how it was donated by Joseph Banks and on the ordered of Napoleon I planted out in 1795 after the then Director hid it in his home garden to protect it during the Revolution. 

Relevant to my tale about Geneva, this male tree had a female branch grafted onto it in 1835. That branch was sourced from the only known female tree then in Europe, in Geneva. I'm presuming it was from Gaussen's garden. In Montpellier it set fruit in 1835 and the now bisexual tree is thriving today, or at least in 2008 when I visited it.

But we are ahead of ourselves. Geneva had lots of lovely large gardens as the eighteenth century drew to a close but no botanic garden. Or at least no public botanic garden. Frédéric-Guillaume Marice created a garden in the 1780s where he planted plants scientifically and took meticulous climatic measurements to better understand their growing requirements.

In 1793, a 0.2 hectare (botanic) garden with a fountain and a place to store preserved plants (a herbarium) was created from a bequest left by Charles Bonnet. In the following year Geneva was short of food, particularly corn, and the 'botanic garden' began to introduce new foods, such as the potato, into local diets and cultivation.

This modest success encouraged the Genevois to plan for a much grander botanic garden in their city, but without any success until Augustin Pyramus de Candolle (a famous botanist in the days when botanists were also famous phycologists - he was a hero of mine during my early studies of algae) arrived in town.

De Candolle had been Director of Montpellier's botanic garden between 1808 and 1806, caring for Banks' gingko when it was entirely male. He returned to his home city in 1816 on the understanding that a proper botanic garden would be built but without any guarantee of funding.

Apart from raising the money, which de Candolle began to do almost immediately, he needed a place to build the garden. As luck would have it, the eruption of Tambora in Indonesia led to another food shortage in Geneva (the year without a summer) and de Candolle claimed an abandoned area to grow potatoes.This time de Candolle was able to maintain public support for botany and in April 1819 the Conservatoire et Jardin Botaniques was officially opened to the public.

So back to my dinner conversation in Dunedin. In four years time Geneva will celebrate the 200 years or so since the volcano in Indonesia led to the growing of potatoes in Geneva which led to the establishment of its renowned botanic garden and which surely helped get a cutting of a local gingko sent to the Director's old haunt in Montpellier. At least that's probably what I was told.

Images: The picture of Tambora volcano is from Wikipedia.

Chiranthodendron pentadactylon, Chiranthodendron pentadactylon (so good I'm posting it twice)

I mentioned this fantastic (in all senses of the word) plant in my late October blog post about Dunedin Botanic Garden. When I returned to Melbourne I found it in flower in my very own Royal Botanic Gardens, and when I bragged about it on Facebook I was told I would have seen it also in Sydney's Royal Botanic Gardens when that was my home territory.

So it's not uncommon. But it remains fantastic. Just take a look at the flower and try and work out what is going on. The velvety outer surface of the flower is typical of its family Sterculiaceae, or a broadly circumscribed Malvaceae if that's your preference. The structure of the flower, though, isn't like any Brachychiton  or Lasiopetalum, typical members of this family (which also includes chocolate, Theobroma).

This is a picture of the Kurrajong (Brachychiton populneus), also in flower in the Royal Botanic Gardens. Not one of the hairiest members of the genus, or family, but you can see the cup-like flower which is a theme I'll return to.

The common names for Chiranthodendron pentadactylon are evocative - Monkey's Hand Tree, Devil's Hand Tree or simply Mexican Hand Tree (according to Wikipedia it is known locally as árbol de las manitas, the tree of little hands, or mācpalxōchitl, the palm flower) - but its botanical name is equally beguiling: Chiranthodendron means 'hand-flowering tree' and pentadactylon means 'five-fingered'.

So clearly something looks like a hand! That something is actually the male part of the flower, a group of five stamens fused together at the base. In this picture each stamen is bearing a line of yellow pollen.

Between two of the fingers of this 5 cm long 'hand' you can see the curved stalk of the female part of the flower, the style. There is only one hand per flower. If you remove the 'hand', you are left with a cup of velvety petal-like structures called sepals, the outer layer of most flowers. The petals themselves are missing, as they are in most Sterculiaceae.

This tree is native to wetter areas of Guatemala and southern Mexico, but grows and flowers happily in Melbourne, Sydney and Dunedin! As you'd expect in a flower of this size and robustness, the pollinators are bats and birds, attracted by nectar in the base of the sepal cup. For them the hand is just something to brush against, getting in the way of their feasting. For the flower, it is presumably an attractive bit of advertising as well as good way to dump pollen onto animal visitors.

Now isn't that just fantastic.

Barking up the right tree

The happenstance discovery of quinine is reasonably well known, but with Cinchona pubescens flowering recently in Melbourne's Royal Botanic Gardens and my rediscovery of a picture I took a few years ago in the streets of Paris, it's time to tell it again.

It is said the treatment of malaria with quinine was the first successful use of a chemical compound to treat an infectious disease. Let's not debate whether the many herbal concoctions used to great effect for thousands of years predate the use of quinine, but simply reflect on the serendipity that led to less people succumbing to malaria.

From early in the seventeenth century the bark of the cinchona tree was used by Jesuit missionaries in South America to treat malaria, most probably borrowing from its use by the native people of the area.

No-one seems sure but it's possible a South American villager with high fever drank from a pool of stagnant water, noticing that it tasted quite bitter. The source of the bitterness was the surrounding quina-quina (as cinchona was called locally). However instead of being poisoned, as he feared, our villager began to recover. And so his village began to use this plant product to treat fever.

This story remains credible despite malaria not occurring in the Americas until the Europeans arrived and quina-quina not being mentioned in any of the early accounts of traditional remedies. Perhaps this happy event coincided with the arrival of the first Europeans or initially helped reduce a fever not related to malaria.

Another variation on the story is now considered to be untrue. In this one the Spanish Countess of Chinchon used the bark of the quina-quina to cure a fever she picked up in Peru, and then introduced the plant into Europe in 1638. True or not, the father of plant taxonomy, Carl Linnaeus, named the genus Cinchona after her.

No matter how it started, the bark took off as a malaria treatment and you can find samples in various museums of economic botany. Here is some in the Economic Botany Collection at Royal Botanic Gardens Kew, and you can find out much more about the history of cinchona on the same website.

Cinchona is one of more than 600 genera in the mostly tropical plant family Rubiaceae, also home to coffee (Coffea) and various other plants containing interesting and important chemicals. There are 23 species of Cinchona, all of which grow naturally in the Andes, and most of which contain at least some quinine. Cinchona pubescens has the most.

So what about this memorial (somewhere near the Jardin du Luxenbourg if I remember rightly) to Professeurs Pierre Pelletier and Joseph Conventou? In 1820 they were the first to extract and purify what they called quinine from the bark of Cinchona. Prior to their work the bark itself was dried, ground to a powder and then mixed directly into a liquid such as wine.

Quinine from cinchona remained the main malaria treatment for the next hundred years, until synthetic products (also from the '-quine' chemical family) proved to be even more effective. However in the late 1950s resistance began to develop in some forms of the malaria bug (Plasmodium falciparum). Quinine itself was reintroduced, particularly for severe cases, and it still remains part of the medical treatment of malaria.

Perhaps more interestingly (at least to an algal botherer - phycologist - such as myself) is that Plasmodium is a close relative of the dinoflagellate, a kind of alga best know for causing red tides and colouring up corals. Because of this relationship, the herbicide roundup can be used to kill Plasmodium cells. Roundup (glyphosate) disrupts chemical reactions within 'plastids', the package of photosynthetic apparati found in all algae and green plants, and there are vestigial plastids in Plasmodium. That's worth a statue, and the name Geoff McFadden from The University of Melbourne (a phycological colleague of mine and keen surfer as this picture from his website demonstrates) would be carved on at least one side.

Thickly hairy but quite beautiful, the Kerrawang

Time for an Australian plant, and some taxonomy. Back in late October I was enjoying the spectacular flowering of the Australian Garden at Royal Botanic Gardens Cranbourne. I was there at the tail end of sprinter (late September), and the place was by any assessment in full bloom. The wattles had finished and we were into the next 'spring' flush.

Now a warning, there is lots of plant nomenclature in this post. Just remember it's good for you....

One plant that stopped us in our tracks was Commersonia (previously Rulingia) dasyphylla, a member of the Malvaceae family, which also includes another of the knock-out plants in the Australian Garden, the Queensland Bottle Tree (Brachychiton rupestris). Both of these genera were included in the family Sterculiaceae not so long ago but the latest molecular sequencing supports them being rolled up with things like hibiscus. Ah, those botanists!

This specimen looks like it's been neatly pruned by one of our horticultural staff, or perhaps a local Swamp Wallaby. I don't think either is true but it's interesting to note that in its native habitat on the central and south coast of New South Wales, a close relative, Commersonia hermanniifolia, is nibbled by Rock Wallabies.

Commersonia now includes most of what we used to call Rulingia. Some taxonomic work by Barbara Whitlock and others, published in 2011, showed that the species of Rulingia and Commersonia are mixed up together in the evolutionary tree and that even though two distinct entities (genera) can be circumscribed, due to the rules of plant nomenclature the name Rulingia disappears from use. Our plant belongs to Commersonia rather than the new Androcalva.

I'm pretty sure this species is dasyphylla because I can see in my close up photo both hairy flowers and white staminodes (a sterile version of the male appendage, the stamina) curled over the top the anthers (bearing pollen). Although without fruit it is apparently difficult to separate this species from Commersonia rugosa and Commersonia breviseta.

Sadly I threw away the small fragment I collected before I could check the hairs on the undersurface of the leaf, another useful place to look for diagnostic features. In Commersonia dasyphylla the undersurface hairs are long, dense and star-shaped (with each of the arms of the star about equal in length) above a layer of smaller hairs. Indeed 'dasys' means thick with hair.

Interestingly, if you like this kind of thing, the species began life in 1810 as Commersonia dasyphylla, before moving across to Rulingia in 1826. It found its way back to Commersonia two hundred years after its first residency there.

The origin of its Aboriginal common name, Kerrawang, seems to be obscure. Other species of Commersonia also carry this name, with adjectives added such as dwarf and wrinkled. Our Kerrawang grows naturally from just south of the Victorian border (e.g. Mount Genoa) all the way up the east coast to Cairns, and Aboriginal communities in New South Wales at least have used the bark to make string.

There is an 1853 report from the Buffalo Range but it hasn't been found in any range or mountain in Victoria bearing this name since. Still, the species may depend on fire for regeneration so it's possible it may pop up in a few new places one day.

Just to show my day at Cranbourne was not all about the Kerrawang and its hairy relatives, this is just a little further up Eucalypt Walk.

More than a menagerie: monkeys' hands, parrots' beaks and f?#@&%! macaws at Dunedin Botanic Garden

You'll notice from the last post I've been in Dunedin, in New Zealand. I was there for an international meeting of botanic gardens (the combined 5th Global Botanic Gardens Congress and 6th Biennial Botanic Gardens Australia and New Zealand Congress). Apart of the usual talking, listening and contemplating, a visit to the local botanic garden was in order.

Dunedin Botanic Garden is a corker. Great horticulture, spectacular plants, and beautiful views and landscapes. The weather was even delightful, with only a few of the rather attractive clouds Dunedin is famous for. It's true, the clouds are quite nice.

The Dunedin Botanic Garden was the first established in New Zealand and celebrates its 150th birthday this year. So old and pretty.

A couple of facts and then you can just enjoy the scenery. It packs a hell of a lot into its 28 hectares and feels like a garden twice that size. There is an aviary, with local and exotic birds, including this pair of macaw that I believe might be trying to produce an egg (but as I'm fond of saying, I'm no zoologist).

There are 6,800 plants including big collections from New Zealand, the Mediterranean, South Africa, Australia and, well, pretty much everywhere in the world.

It's justly famous for its Rhododendrons, 3000 in all, and they were brightly in flower for our visit. The azaleas (as the sign says: Azaleas are Rhododendrons, with distinctive features...) were typically garish yellows and oranges that send my digital camera into chromatic spasms. But the Rhododendron Rhododendrons were gorgeous and reproducible colours.

Lots of great flowers and towering trees, including the floral emblem of the botanic garden, the Clianthus puniceus (Parrot's Beak), and the Mexican Chiranthodendron pentadatylon (Monkey's Hand - you can see why from the fallen flower parts on the path).

As for the rest, well just enjoy without my lewd and rather shallow commentary...

Every Scottish city in New Zealand needs a castle (garden)

Last week I was on a bus circumnavigating (almost) Otago Harbour, around Dunedin in New Zealand's South Island. This wasn't the bus but this was the castle garden where the bus journey finished.

After a little scepticism - our narrating bus driver was a fascinating mix of James Joyce and John Clark and his description of Larnach Castle focused on suicide and the 'uniqueness' of the design - I was won over by the garden. Really charming design and some great plants. The mix of colours was sometimes a little hectic but the gardeners past and present are clearly having fun.

The Barker family bought the property in the 1967 and have been restoring the house and garden ever since. Margaret Barker met us on the Raised Lawn in front of the house to tell us a little of its history from 1870 through to the challenges of the 50 years they've been working on it.

William Larnach, the Australian banker who built and lived in the castle with each of his three wives, (in)famously committed suicide in New Zealand's House of Parliament. I gather from our Joycean bus driver, Shane, that he was unhappy to discover his last wife was having an affair with his son. But I may have misconstrued the narrative. Safer to get back to plants...

The Kowhai (Sophora tetraptera) is considered by some to be the national flower of New Zealand, competing strongly with the New Zealand Christmas Tree or Pohutukawa. It also competes, in my head at least, with Sophora toromiro, the now extinct species from Easter Island that we grow in Melbourne's Royal Botanic Gardens. Take a look at pictures of that species on the web and compare with the Kowhai. 

Here are two views from the South Seas Garden, with the wavy hedge as your reference point. First looking up hill, then down, way down to the Otago Harbour.

The view across Otago Harbour was pretty spectacular, but as with the whole journey around the city, there was plenty of gorse for concern (sorry...the yellow stuff).

Another showy pea flower from the local Clianthus puniceus, and there it was in flower at Larnach Castle in any colour you want...as long as that's white or red.

Here are two friends and colleagues from Chicago Botanic Gardens, softly out of focus behind real white ducks and next to real white sculpture.

And it wouldn't be a New Zealand garden, or roadside, without some Echium.

Finally, the castle itself. It is, well, as Shane put it, unique. But it does have some orange algae (Trentepohlia) gracing its front steps, so it's a good substrate.