Tuesday, 27 January 2015

Eel heads and floating flowers

All seems calm at the Ornamental Lake in Melbourne's Royal Botanic Garden. It's a wintery morning before a hot summer's day in late January. Fairly typical weather for this city.

There are a few (sub)tropical trees still flowering but the Jacarandas, Brachychitons and Cape Chestnuts have finished. Recent rain has kept the Gardens green but you can sense that things are about to curl and brown, with most plants shutting down for the summer.

In the lake itself there is plenty of algae, mostly submerged clumps of a green alga called Spirogyra, which do from time to time float to the top. The Purple Loosestrife (Lythrum salicaria) continues to do what it does best on the floating islands - bloom, bloom and then bloom some more.

In front of this floating wall of grass and loosestrife you can see mats of algal and aquatic plants accumulating at this north-east corner of the lake. The dominant aquatic plant is Eelgrass, Vallisneria australis, a Victorian native that extends all the way up to near the Queensland-New South Wales border. There are seven or so species of Vallisneria in Australia, mostly tropical, and mostly with long ribbon-like leaves - hence the common name.

For most of the year you can just ignore it. Eelgrass is there, doing all kinds of good things in the lake in terms of habitat and nutrient recycling, but for you and I its a case of move along, nothing to see here.

But in late January something does happen. The first thing you might notice are tiny eel heads poking up out of the water. I say eel* heads but that's just me being poetic and metaphoric. These are the, by the time I got to see them 'spent', female flowers.

The next thing you (might) notice is an intricate lacework of white fluff. These are the male flowers.

As you will have gathered, this is a plant with single-sex flowers. That's not unusual per se in the plant world but the way these flowers work is. Eelgrass has a particular method of pollination called, entirely unhelpfully, ‘Type III’. It's only found in Vallisneria and other members of its family Hydrocharitaceae.

The key feature is the complete detachment of male flowers as buds from a sheathed stalk at the base of the plant. These tiny flowers float to the surface where they open fully and then coagulate together in floating rafts, drifting around with the wind and current.

There are minor variations to 'Type III' pollination, and in Eelgrass and two other related genera, the pollen has to remain dry. So the flowers actually float so that the pollen bearing bits are held aloft, above the water! You see them here hovering around a slightly submerged eel head, a flower already fertilised and having lost its petals (and sepals).

The receptive part of the female flower (the style) also has to remain dry, before fertilisation. At first the style is protected by the tightly wrapped petals (and sepals). By the time the flower opens, its long flexible stalk has extended it through the water surface. There it eventually comes in contact with the drifting male flowers and fertilisation takes place.

All the female flowers I saw and photographed were fertilised and beginning to set seed. After pollination the stalk of the female flower becomes spiralled, dragging the developing fruit underwater. The seed are eventually released in the murk beneath, to be washed around and settle somewhere new.

Yes really. That's what is going on in and on the lake while the rest of the garden is bunkering down for late summer.

* As our website boasts, the Ornamental Lake is home to a healthy population of Short-finned Eels (Anguilla australis). These eels live hereabouts before the arrival of Europeans, and they enjoy the moderately shallow parts of the lake where they feed on crustaceans, frogs, insects and worms. So much so that they can reach 1.3 metres long. Eventually though they swim and slither their way into coastal estuaries where they swim 4,000 km to spawning grounds in the South Coral Sea. Because eels can breathe through their mucus-coated skin, they can in fact slither overland when it's damp (e.g. at night). At breeding time the mature eels are drawn towards flowing water, and find their way through drains to the Yarra River. The leaf-shaped larvae (soon becoming what we call 'glass eels') hatch off New Caledonia and are carried southwards on ocean currents, until at the age of one to three years when they (now 'elvers') migrate up Victorian rivers and streams, until some call our Ornamental Lake home. 

[Thanks to Neville Walsh for directing my attention to the curious botanical phenomenon.]

Tuesday, 20 January 2015

The sweet aftertaste of artichoke

There are lots of phenolics in Globe Artichokes. To be fair, there are lots of phenolics in the plant kingdom more generally. Phenolics are, in chemical terms, compounds with one or more of what chemists like to call 'aromatic rings' and with one or more of what chemists like to call 'hydroxyl groups'.

[The simplest aromatic ring is the one with six carbons and six hydrogens, drawn as a hexagon with every second side with a double line. A hydroxyl group is represented as an O (oxygen) with an H (hydrogen) sticking off one side and the hexagon or something similar off the other.]

Phenolics are produced by most plants as secondary metabolites, that is products not used directly for growth or reproduction, but for things like protection against pests, against excess radiation or add colour to various plant parts. So far we know of 8,000 different phenolic compounds in plants.

Phenolics add some of the more interesting flavours to fruit and vegetables, such as the bitterness and astringency of berries, and give tea, coffee, beer and wine their kick.

One of the phenolics in the Globe Artichoke is called cynarin. It inhibits taste buds that detect sweetness. And as you eat other things afterwards, the cynarin layer in your mouth is gradually removed making everything suddenly seem very sweet. Miraculin does the same thing in the so-called Miracle Fruit.

To test this I went to my local shops to find a fresh Globe Artichoke. Sadly, none to be found. So I thought I'd test a grilled and pickled version, to see if the phenolics survive all that processing.

Turns out they don't. At least in the one I tasted and then followed by a lime. I ventured further afield and eventually found some fresh artichokes (below) which when eaten after boiling caused water to taste a little sweet (although the sweetness emerged a few minutes later) and very slightly made a lemon seem less sour (not exactly sweet, although again, a few minutes later I could taste sweetened lemon in my mouth). Not quite as miraculous as Synsepalum dulcificum, but a little bit fun.

By the way, the artichoke I'm talking about here is the Globe Artichoke, a thistle, Cynara cardunculus (you can see where the phenolic name comes from). The Jerusalem Artichoke, Helianthus tuberosus, illustrated below, is also in the daisy family but not a thistle and more closely related to the Sunflower (Helianthus annuus). And of course rather than the flower head, you eat this, the tuber.

And not all Cynara cardunculus are Globe Artichokes. While there is some debate over what names to use, there are usually two subspecies recognised, one for the Globe Artichoke, the other the Cardoon (it again is usually divided into two varieties, the cultivated and the wild Cardoon).

The Cardoon is also eaten, and was described recently as 'a fantasy dragon of a vegetable: what celery would look like it went through the Looking Glass and ended up in the Game of Thrones' (do check out the photograph in this link - you'll soon get the idea). They taste a bit like artichokes but you eat the stem rather than the heart of the flower head.

 Thanks to Janet O'Hehir who many months ago mentioned this characteristic of the Globe Artichoke to me after I wrote about the Miracle Fruit. And the beautiful drawing of an artichoke, Cynara cardunculus var. fortissima, is by Debra Bartlett. It was bought last year by the Royal Botanic Gardens Melbourne Director's Circle for the State Botanical Collection, and resides at the moment on the wall in my office. (I can't track down this varietal name but presume it is a Globe Artichoke.) The flowers photographed are in front of the Alpine House at Kew Gardens in 2011.

Tuesday, 13 January 2015

The simple enjoyment of an orange, green alga

I've mentioned these orange cushions in passing a couple of times but the organism responsible for them is worth a little more attention. While it's an alga rather than a plant, in the evolutionary tree of life it's in the branch that splits off just below the green plants - so not too distantly related.

It's called Trentepohlia and you can find it on rocks or wood, in pretty much any part of the world. In Victoria (Australia), drive from Halls Gap to the Zumsteins, through the Grampians/Gariwerd National Park, and you'll see a lot of it on the roadside at slightly higher elevations.

Here on a rock wall in a village in the West Pinines, an hour or so from Durham in northern England, it thrives. There are about 40 species and this one is probably Trentepohlia aurea, a common species in these parts (although it may be applied more commonly than it actually occurs given the lack of recent taxonomic work on this group - studies by Mike Guiry and colleagues are the exception).

Although it is orange in colour, it is classified as a green alga. And if you look under a microscope you'll see that it is fundamentally green overlaid with an orange pigment, called haematochrome. In this picture the green dominates but sometimes it's all orange, orange, orange...

It's thought that the haematochrome helps protect the alga in the very exposed places it finds to live - out of water, on walls, often in full sun.

Sometimes it might be confused with various red or orange lichens such as those found on coastal rocks in Australia and elsewhere. It might also look like a clapped out moss I guess. A quick peak under the microscope will confirm it's identity but generally if in the field it is orange in colour and velvety in texture it's likely to a Trentepohlia. (Although be aware that this alga also finds it's way into the algal-fungal symbiosis we call a lichen.)

The UK wall featured here is said to be the densest and most extensive population of this alga in England. I have no way of testing that but other patches I saw were certainly smaller and the local community is justly proud of its orange wall. The habitat must suit it, and the wall would be old enough for this alga to have grown to such an extent (Trentepohlia is often described as growing 'very slowly' and I would expect it would take many decades or centuries to achieve this result).

Interestingly other walls nearby support mosses and lichens, due to either microclimate, or age and disturbance I suppose.

None of these growths will particularly harm the wall and when Trentepohlia grows on tree trunks it doesn't cause any damage. Another genus of algae in the same family (Trentepohliaceae) called Cephaleuros is less popular because it can become parasitic on tropical crops such as cocoa and tea, leading to extensive foliage damage.

Trentepohlia, like most algae, is simply there to be enjoyed.

Images: from my trip to Durham (skyline below...) in July last year, except for the microscope picture which I have copied from the University of Wisconsin Madison, Botany 330, Algae webpages.

Tuesday, 6 January 2015

Nick's Lime Tree (Plant Portrait XI*)

On 20 December 2014, musician and writer Nick Cave planted a lime tree on Picnic Point, beside the Ornamental Lake, in Royal Botanic Gardens Melbourne. It was our 103rd commemorative planting, and the first for over a century that didn't involve a governor general, governor, queen, duke, countess, marquis...(you get the idea)...or associate of the botanic gardens.

Even then, in the early twentieth century, there were usually links to title. Opera singer Nellie Melba was a Dame when she planted a Poplar (Populus) in 1903, which has since died, and the pianist and composer Ignacy Paderewski was the third Prime Minister of Poland when in 1904 he planted a Buckeye (Aesculus), still living.  

We have a plan now to celebrate people associated with Melbourne who have made a major contribution to the cultural life of Australia and beyond, with or without honorifics. Names on our list include Ron Barrassi, Cate Blanchett, Nick Cave, Barry Humphries, Michael Leunig and Geoffrey Rush (at the moment the gender balance is a bit like the first Federal Coalition Cabinet).

Many Melburnians of my age have grown up, or not, with Nick Cave (pictured here in the Royal Botanic Gardens with a mature Lime Tree). His music has been, almost literally, the soundtrack to our lives: from the The Boys Next Door/The Birthday Party's Mr Clarinet and Zoo Music Girl at student parties or live at the Prince of Wales in St Kilda, through the bands Bad Seeds and Grinderman, to recent musical masterpieces such as Higgs Boson Blues. Along the way there were films, books and other collected materials.  

Nick Cave started performing in Melbourne but soon became a musician of the world, and resident of Germany, Brazil and now the UK. His lyrics and novels have been the subject of workshops and academic scrutiny. Earlier this year Gerard Elson, in the magazine Island, compared him to Bob Dylan, Leonard Cohen and the American poet John Berryman. In The Monthly, Robert Forster places Nick Cave at the top of his list of Australian 'rock stars', ever.

Nick's writing and music is by any standard clever, evocative and fun. At its peak it's goose-bumps inducing, whether mellow or murderous. While there are plenty of plant references dotted through Nick’s lyrics - he was perhaps the first Australian 'rock' artist to reference nature in this songs - the selection of tree planters is not about plants, and mostly it never has been. It's part of the Royal Botanic Gardens celebrating its place in the cultural life of Melbourne, as well as attracting visitors to a place (for whatever reason) so we can drench them in the beauty and importance of plants.

Nick Cave's significant contribution to art and to Melbourne make him an obvious first choice in this reinventing of the commemorative tree planting program. While others on the list may be better known, we felt it was important with this first choice to pick someone less conventional and a little provocative. Someone who has extended the culture of Melbourne geographically and creatively. Someone who reflects modern Melbourne.

We won't rush the next planting and I expect we'll do one or two a year. I like the idea of linking the tree, at least tangentially, to the person doing the planting but it needs to be a tree we want and to fit into the Gardens landscape.  

The tree this time is a Lime, a connection to one of Nick's most moving songs where he says 'I put my hand over hers, down in the Lime Tree Arbour'. This particular lime is called Henry's Lime, Tilia henryana, again a nod to one of Nick's creations, the 1992 album Henry's Dream. 

This is the first time we've grown Tilia henryana. It's an Ernest Wilson collected species from China, introduced to the West around 1901 and named after another prolific plant collector, Augustine Henry. The leaves are described as 'sea-green' when mature, glossy above and silvery below. But the new leaves, which you can see now (and pictured at the top of the post), are silvery-pink or copper-coloured, and produced in mid to late summer as well as spring.

So this flush of growth is expected, although perhaps not the best thing to do this time of year in Australia. In his recent book on Henry, Seamus O'Brien describes this species as 'the largest of all the lime trees from western and central China, and without a doubt the most beautiful'.

Thanks Nick. Not quite a Lime Tree Arbour, but a beautiful Henry’s Lime to celebrate a major contribution to world culture, from Melbourne.

Notes: I held back on posting this story having already pasted most of the photos in my Facebook page, and with the Sunday Age running a photo story the day after, but the tree is doing so well, and the new growth is so pretty, I can't resist.

Tuesday, 30 December 2014

Maiden in a bottle

Joesph that is, not some sweet innocent lady from yesteryear. And it's his enthusiasm rather than his essence flavouring this particular drink, one you might consider for your New Year's tipple.

Maidenii is a drink I discovered in the penultimate course of a typically Australian and plant-rich meal at Ben Shewry's Attica restaurant in Ripponlea. Regularly included in the Top 50 restaurants of the world, top or near top in Australia, you'd expect to make a discovery or to during one of the eight courses (plus odds and ends of self-picked herbs and little things to try).

It's a vermouth and I've so far only imbibed it with pears. So this is not a review of it's finer qualities as the splash in a martini, the mixer in another of your favourite cocktail or straight on ice.

It comes, I think, from Sutton Grange near Castlemaine, and includes 34 'botanicals', a dozen of them native to Australia. Now botanicals is a term we are becoming used to with gin. In fact you went to a gin tasting you'd think you were drinking a rainforest in a glass, the botancial elixir of life, when in fact it's about 50% alcohol from fermented grain dosed with juniper, plus a few other plants for flavouring.

Vermouth is wine fortified with another spirit, in the case of Maidenii also from grape, plus some Wormwood (Artemisia, the plant also giving Absinthe its charm). In other vermouths, a sweetener may also be added.

In Maidenii, there 33 additional botanicals (I don't think they include the grape fruit in these, but perhaps they do). The 'heroes' are wattle (Acacia) seed, Sea Parsley (Apium prostratum), Native or River Mint (Mentha australis) and Strawberry Gum (Eucalyptus olida). This means you'll find these plant in all three blends of Maidenii vermouth, and presumably in decent quantities.

Their classic blend also has Orange (Citrus 'Valencia' or similar) zest, Bay Leaf (Lauris nobilis) and Gentian (Gentiana) root; the dry blend Kaffir Lime (Citrus hystrix) leaf, Nigella and Japanese Gentian (Gentiana scabra); and the sweet blend, Grapefruit (Citrus x paradisi), Mace (Myristica) and Angelica root. The base wine, and therefore grape cultivar, also varies among the three blends.

Joseph Maiden himself was the Director of Sydney's Botanic Gardens between 1896 and 1924, a role I held myself between 2004 and 2011 (and this hazy image is part of the portrait on what was then the Director's Office wall). Maiden started the National Herbarium of New South Wales (the library of preserved plants, now over 1.2 million strong) in Sydney, promoted and helped establish Wattle Day, and became an expert in the genus Eucalptus. He was much more of course and Lionel Gilbert wrote a lovely book and his life and influence called The Little Giant

Could I taste the botanicals in my pear desert? Not really. Although I do remember the Pyrus. Otherwise there was too much else going on aboard this wooden plate, all of it very tasty.

[Notes: For those of you into the chemistry of Australian plants (thanks Dan Murphy) there is no indication that the wattle named after Joseph Maiden, Acacia maidenii, is represented in any way within the drink.]

Tuesday, 23 December 2014

A merry bracteate Christmas

As a special Christmas treat, some colourful and showy flowers that aren't, entirely, flowers.

Around Christmas our thoughts turn to... Poinsettia. The bright red flowers seem to fit perfectly with our festive spirit. It's all a contrived of course, the poinsettia flowering. As I've explained before, it flowers naturally during winter so we manipulate it in glasshouses for this Christmas flush.

(That said, the plant photographed for this post sits on a window sill in the office of our Manager of Plant Sciences, Dr Frank Udovicic. Previously it has lived on other window sills in the National Herbarium of Victoria - outside the designated 'clean areas' where the preserved collections are held - but never subject to special lighting of any kind. So why it flowers in November, when this picture was taken, I'm not sure. Perhaps to do with the artificial lighting in Frank's office?)

In Poinsettia, it is not the flower we enjoy but the leaves around the flower, which we call bracts. They colour up when the plants becomes fertile, clearly have a role in attracting pollinators to the otherwise insignificant flowers, as in this Poinsettia, Euphorbia pulcherrima.

Bracts are special leaves, adapted in size, shape or colour to make the floral display even more attractive. Bougainvillea is another plant with showy bracts around insignificant flowers, in this case three or six bracts around a clutch of three flowers. These fine specimens are from the Xishuangbanna Tropical Flower and Plant Garden in Jinghong, which I visited in 2004.

There are lots of familiar plants with bracts around the infloresence, or group of flowers. Think daisies with their simple flowers (called florets) all grouped together in a head, often surrounded by a row of colourful bractsIf the colourful outer layer is soft and fleshy - for example, the Sunflower, Helianthus annuus - it is more likely made of real petals, each attached to a floret in the outer ring of the flowerhead. But in these pretty Everlasting Daisies (Xerochrysum bracteatum) from The Australian Botanic Garden, Mount Annan (out of Sydney), the 'flowers' are created by a clumps of florets surrounded by pink or white papery bracts. 

Another favourite of mine is Davidia involucra, the Handkerchief Tree. I saw a wonderful specimen of this in late October in Tieva Tara, the private garden of John and Judith Brand at Mount Macedon. Like in the daisies and Bougainvillea, the white 'handkerchiefs' are at the base of a cluster of flowers.

And then you have hellebores with their petals really being sepals, the layer usually outside the colourful petal layer. More on that in a previous post where I've given them enough photographic exposure!

Clearly the bracts, or specialised flowers, in these plants are doing what petals do in most single flowers: attracting pollinators. Given that flower parts are modified leaves anyway it's not much of a stretch to understand why sometimes evolution favours big showy leaves that just happen to be nearby instead of petals (or in the case of daisies, flowers clumped together with different structures and roles.) And we can be thankful for that. Say Merry Christmas this year with a bunch of bracts!

Credit: Thanks Frank Udovicic for the suggested topic of this post and Gerhard Prenner for reminding me that the coloured parts of a sunflower head are in fact real petals, not bracts (resulting in an update to this post).

Tuesday, 16 December 2014

Talking Plants on the Wireless

Earlier this year landscape designer Jim Fogarty and I were walking back from the ABC Studios after talking to Lindy Burns on 774 ABC Evenings about the upcoming Hampton Court Palace Flower Show. We were bemoaning the lack of a gardening show on radio that covered more than how to garden.

There are some great talk-back sessions by experts in horticulture, and occasionally the chance for them to cover a topic in a little more depth. But where was the place for discussing the big questions in horticulture, a chance to argue and debate about gardens and gardening?

We are very polite in the gardening world and tend to make every segment upbeat and life-affirming. Not that we need biff and blustering but a little prodding and disagreement wouldn't go astray now and then.

Mulling over this the next day I thought a panel show might be the answer. I wanted it to be national, and I wanted it to be done with style and integrity. ABC Radio National (RN) seemed to be the right vehicle.

So I emailed Robyn Williams, presenter of the RN Science Show for 30 years, who has always been supportive of botanic gardens and knew I could at least string a few words together. I thought he would be a good sounding board for a mad idea. This was the pitch.

Within minutes Robyn Williams had forwarded on my email to an RN commissioning editor, and within hours I received the reply via Robyn that there was certainly interest. RN had always had a hankering for a gardening show of some kind and this concept was appealing. Robyn recommended me warmly, which I'm sure helped. 

After some paperwork and internal ABC decision making we were invited to prepare a pilot episode with Amanda Smith (above; presenter of The Body Sphere, and producer of many great RN shows) producing. The show format evolved into a half-hour episode, including a 10-minute panel discussion, a plant of the week (Under the Microscope), a 5-minute outdoor interview (In the Garden) and a final whip around for what was good (laurel) or bad (thorn) in horticulture that week. 

I would host, Jim would be a regular guest and join me from the start of the show. A second guest could come in during our Under the Microscope session and stay for the panel discussion, to be joined by a third guest for that segment and the laurels/thorns. We would build to four of us chatting about horticulture...

For the pilot, we invited Damon Young (above, left), a philosopher, and Teena Crawford (above, third from left), a plant grower, to be our guests, staking out our territory as horticulture expertise within a wider cultural context. The pilot was viewed positively and we agreed to provide a series of six shows to run over Christmas with the pilot becoming the first episode. 

Does it meet the brief? Does it work? Is it any good? It's over to you. I'm Tim Entwisle, on RN, for Talking Plants  You can hear me at 9 am on Sunday mornings, or download the show from the Radio National website

Tuesday, 9 December 2014

Pollen shot a danger to insect life

I've always enjoyed firing off the trigger mechanism of the Trigger Plant (Stylidium) flower and it was one the subject of one of my first posts on Talking Plants, back in 2008. The fused male and female parts of the flower are cocked, ready to flick back into the middle of the flower when an insect (or my twig) makes contact with the sensitive area at the base of the trigger (a form of thigmotaxis, if you recall). This all happens within 20 milliseconds.

There are contenders for the plant speed record. The Bunchberry Dogwood (Cornus canadensis) has what are called 'exploding flowers', with pollen fired off at a reputed speed of 6 metres per second, just under half a millisecond after opening. Impatiens pallida has seeds that reach similar speeds and the Sandbox Tree, Hura crepitans, is faster, with seeds reputedly reaching speeds of up to 70 metres per second.

But let's back track to Cornus canadensis. The Missouri Botanical Garden Angiosperm Phylogeny Group website states that 'the anthers of Cornus canadensis have explosive dehiscence; the maximum acceleration rate of the pollen grains has been estimated at 24,000 metres per second squared (remember that acceleration is a measure of the change in velocity - that is, metre per second, per second...).

Cornus canadensis

To put that in context, this acceleration is 800 times that experienced by astronauts on liftoff from Earth. The pollen is travelling about 4 metres per second (14 kilometres per hour) when it leaves the flower. Botanist Ted Mosquin wrote a charming article on 'the explosive pollination mechanism in Cornus cadensis' in 1985 and summarised it online in 1998, in Botanical Electronic News.

Mosquin explains that the Bunchberry Dogwood is well armed for speed. It has a 'sensitive antenna-like structure' sticking out of one of the petals in the unopened flower, 'petals on a tensile spring' and male parts (stamens) with what are called 'elbow springs'. It's these stamen elbows that fling the pollen upwards and out of the flower.

In most plants, including the Trigger Plant, the firing mechanims involves one (or a fused part) of the flower working alone or perhaps constrained a little by petals. Ted Mosquin cites species of Pilea (the Artillery Plant), Urtica, Kalmia, Medicago, Sarothamnus, Lopezia, Hyptis, Hucuna, Ilex, Odontonema and Ravenala, noting that there are also some with 'less rapid floral movements related to pollination'.

The flower of the Bunchberry Dogwood is one of those flowers that isn't. What we often call the flower is a collection of a dozen or so inconsicuous flowers, within four big showy bracts. Most of the floral parts (and the bracts) are white, greenish-yellow or generally light in colour. The only exception are the female bits, which are dark purple and therefore quite prominent.

According to Ted Mosquin, the first thing you notice about the Bunchberry flower is that it is either in bud (as all are in the above, with the little antenna pointing skywards) or fully open. If you look closely you also notice that in open flowers the pollen has all been released (from the anthers). This is because when the antenna is prodded by a visiting insect or botanist the flower not only opens but there is an immediate explosive release of pollen. The petals peal back and the anthers spring out - flexing their elbows no doubt - spraying their entire pollen load into the air. The anthers are actually fully open in the bud, so that when the flower is triggered the pollen is ready to fly.

The flower has no need of nectar and this in effect wind pollination, set in motion by an insect, rather than what we would normally call 'insect pollination'. It would hard for an insect to eat the pollen, which might be part of why such a mechanism evolved. This triggering is so sensitive that any insect, even a small midge, can set it off. In fact Mosquin muses that the popping of the flower may well 'pose some theat to the life and limb of the smaller and more fragile of the woodland insects'.

It seems this explosion, or pop, happens extremely quickly and is hard to observe with the naked eye - one moment the flower is closed, the next fully open. It all happens in less than 0.4 milliseconds, 'less time than it takes for a bullet to travel the length of a rifle barrel'! Mosquin's implied concerns would seem warranted, so look out for insects riddled with pollen holes.

Images: unusually I've had to source all my pictures from other sources having never seen this plant myself. The picture at the top from the Adirondack Almanack, the second from White Flower Farm and the last from Portland Nursery.

Tuesday, 2 December 2014

Hop, a wolf in plant's clothing

It's time to return to Hop. Last time it was all about beer. This time, it's only partly about beer.

Seeing pots of Hop for sale at the Diggers garden at St Erth, near Blackwood, I recalled an impressive display by this climber at the Cloisters in New York. You don't have to travel that far to see it thriving, but I've used pictures from that visit back in September.

Humulus lupulus is such a euphonious name, you've got to ask what it means. It's Linnaean, described by Carl Linnaeus back in the eighteenth century. The genus name may, or may not, have something to do with humus and the rich soil it favours. Or it may be from an old German word for hop, humela.

'Lupulus' is easier, from the Latin for wolf lupus. Apparently the first century Roman naturalist, Pliny the Elder, used this term in describing how hop smothered and strangled the plant it grew on, much like a wolf does to a sheep. In fact Hop has been called Willow-wolf after its propensity for wolfing willows in this manner.

Its growth habit is clearly of note: the common name 'hop' is from an early Anglo-saxon word meaning to climb.

There is no need to panic though, noted naturalist Charles Darwin recorded that the stems make one revolution every two hours and eight minutes on a warm sunny day. You have plenty of time to escape, unlike the willow. Darwin also noticed that the twining was clockwise, but more on that in a previous post.

It's a vigorous plant but presumably because viable seed is uncommon, it hasn't become a severe weed in Australia. However it is 'naturalised' in various parts of Tasmania, and in a couple of coastal areas of Victoria. You should also take care where you plant it: the description of Hop in Gardening Australia's Flora includes 'suckers far and wide from its questing rhizomes'.

These days Hop is classified in the family Cannabaceae, along with Cannabis of course, as well as the widely planted and sometimes weedy garden tree, the Hackberry (Celtis). All three genera have more or less hand-shaped (lobed) leaves.

Hop is native to Europe and western Asia (or according to some sources, south-east Asia) and has been used to make beer for around 10,000 years. As is well known, it became part of the beer recipe to stop the drink going sour, back in the days (prior to the eighteenth century) when beer was safer to drink than water.

Plants produce either male or female flowers, not both. And it is the female flowers that are used in beer-brewing. They are what we call hops, and what gives your beer that bewitching bitterness. Unfertilised flowers are best, so crops are either exclusively female or with a few male plants left in to assist with the control of mildew (the receptive part of the female flower, the stigma, is prime site for fungal infection and it withers are fertilisation).

These pictures show clusters of female flowers, or cones, covered in papery bracts. Lupulin glands, containing the sought after oils, are buried within these bracts and then another layer of what we call bracteoles. But you can grow this plant for its horticultural beauty if you like.

Tuesday, 25 November 2014

Deane's Wattle not so high on a hill top

Climbing The Hill at Pyramid Hill earlier this year (in March), I was reminded of the first time I sighted the nearby Mount Witchyproof. At 43 metres, Mount Witchyproof is reputedly the smallest registered mountain, and it doesn't live up to any altitudinal expectation. At least The Hill, at much the same height I think, is just called a hill.

The vegetation is a bit clapped out (that's the technical term) but it has few interesting specimens. Wattle season, sprinter, is now well finished but I thought I'd feature an Acacia. In this case the wattle was in full flower in March so it's one of the many that flowers outside sprinter - sprinter just happens to be the peak wattle flowering season for much of Australia.

Acacia deanei, or Deane's Wattle to its friends, is one of the feathery leaved wattles. Most wattles have what are called phyllodes, flat blades that are actually modified leaf stalks rather than true leaves. They start off with feathery leaves when young but the mature plant has only phyllodes (think Golden Wattle, Acacia pycnantha).

A Deane's Wattle plant starts and finishes with feathery leaves. Each leaf consists of 2-8 pairs of what are called pinnae, and each pinna (singular) has 10-30 pinnules (littler pinnae...). You find this kind of structure in some ferns and in other wattles, like the common Black and Silver Wattle.

But Deane's Wattle is not so common, at least in Victoria. There are two subspecies, one called deanii (like the species, name after Mr Deane who first collected the species from Gilgandra in New South Wales) and one paucijuga (meaning fewer of the pinna or pinnules, but in this case also a reference to the smaller pinnules).

In Victoria, the first subspecies is only found near Chiltern, on the Murray River. It is more common in New South Wales and into southern Queensland. The paucijuga subspecies is scattered around the State but primarily in the north-central parts, and extending up into New South Wales. This is the one we saw on and near Pyramid Hill.

At first glance both subspecies might look like the Black Wattle, Acacia mearnsii, but that species has more pinnae and more pinnules, and the pinnules are smaller.Their ranges overlap a bit but Deane's Wattle is the only one you'll find growing naturally up towards the Murray.

We have preserved collections in the National Herbarium of Victoria from plants in flower (of both subspecies) pretty much anytime of the year, although mostly in summer. Which is a good thing. Apart from a few salt-bushes and a weed or two, it was one of the few colourful plants in flower at that time of year in the hills and mountains of northern Victoria.

As we enter the final week of sprummer, there is plenty in flower at the moment in our gardens and in the bush. The purple haze of jacaranda flowering has at last made its way to Melbourne and the Cape Chestnut is pretty in pink. The Sydney Red Gum, Angophora costata, is particularly stunning in nature and in nature-strips. 

The 4-month long summer that I favour for much of southern Australia is about to begin. This is 'down time' for many of our Australian plants, with notable exceptions such as the Hyacinth Orchid (Dipodium). By the time we get to March there will be little in flower so we need to savour the likes of Deane's Wattle.

Tuesday, 18 November 2014

Cultivating Cancer Weed

For someone who loves to tell stories about plants that change the world for the better - Cinchona (quinine), Salix (asprin),  Hevea (rubber) and of course Coffea (ahhhh) - you think I'd be thrilled to discover that active chemical in the gel I smeared over my face to fix some skin blemishes was discovered in a plant.

Instead I started to doubt its efficacy. Was Picato really something to cure my latent skin cancers or was this something just to make me feel better? But then I thought about quinine and asprins, and decided it was a good thing as long as it was well tested and the extract was carefully measured. Not for me a tea made of some local weed with the hope that it might contain just the Goldilocks amount of an elixir. I don't want to be poisoned, misled or conned. And thanks to an Australian scientist, Professor Jim Aylward, and his mother, that doesn't have to be the case.

But first let's look at the plant in question, Euphorbia peplus. It's a small herb native to northern Africa, Europe and western Asia but now naturalised widely around the world, including much of southern and eastern Australia, and doing quite nicely in my backyard. It arrived in Australia shortly after European settlement and has become a common weed of gardens, paths and crops. Although well established it is generally not an aggressive invasive, except in few localised areas (e.g. it is listed as one of top 10 coastal weeds of concern in southern Western Australia).

The plant is soft and bright green, up to about 20 cm tall, with oval or spade-shaped leaves and umbrella-like clusters of green flowers or fruits at the top. The stems are usually reddish at the base. I'm sure you've pulled them out of your brick work or path at some time.

Common names include Petty Spurge or along with lots of other euphorbs, Milk Weed. It's even called by some, Cancer Weed - in a curative rather than causative sense I think - or Radium Weed. I'm presuming 'radium' again refers to its powers of good, rather than evil.

I should point out here that the plant is poisonous to us, and to many animals, and should not be ingested. Although unspecified mild doses have been used as a laxative you might keep in mind that seventeenth century herbalist Nicholas Culpeper described its action as 'working violently by vomit and stool'.  And as with most euphorbs, skin contact with the milky sap can cause dermatitis.

Ironically, or not, it is the sap that has been used for centuries to cure skin problems, particularly warts. There are plenty of reports of people using sap direct from the stem to fix all kinds of blemishes and more serious ailments, and many of us have dobbed a dab of white latex from this plant onto a wart just to see what happens. Although far more expensive, I prefer and would always recommend clinically tested and precise dosages for the face.

Back to our Australian scientist, Professor Aylward. In a radio interview in 2009, he said his mother cajoled him into studying the properties of this plant after she found it successful home remedy for treating sunspots. That was in 1997 when Aylward and his team of Queensland scientists discovered and isolated the active compound in Euphorbia peplus.

Named ingenol mebute, this chemical kills rapidly dividing and growing cells, of the kind you find in a sun spot or potential cancerous cluster.

By 2009 clinical trials were in place and in 2013 the product was released for general use in the form of three tiny tubes of gel to be applied one each day for three days. After fifteen days of ruddy complexion your skin becomes blotch and cancer free, at least for a while.

Well, I did it and it seemed to work just fine. In the backyard the Euphorbia peplus thrives, no matter how many times I rip it from the garden. Presumably its toxic sap wards off other predators, and the ability to produce these flowers and fruits within weeks of germinating must help.

Images: The shots of Euphorbia peplus are all taken in my backyard, the tiny tube of Picato gel in my kitchen. The last two pictures may help you work out whether it is the paired leaves or the tucked and pleated fruits that inspired the species name, a reference to the simple peplos garment worn by women in Ancient Greece.