Plants in the Mist

You learn a lot about a plant when you grow it in your garden. You can read all you like in books and on the internet but only when you watch it day by day do you get to really know the plant.

I’ve just discovered the flowers of a coffee bush all open within the same day or two. On Boxing Day (see previous blog) I excitedly photographed the first flower, the next day there were are all open, up and down every stem.

There is at least a second flush on the way (in bud) but the plant seems to like mass flowering. The flowers were also very short lived, opening for only 24-48 hours, with the female receptive stalk (the style) remaining after the petals and the male bits were all brown and shrivelled.

I’m sure I could find that out somewhere in the botanical literature, but I wouldn’t have thought to look. It’s a bit like trying to piece together how gorillas live without someone like Dian Fossey living amongst them for a while. You need to wake up each morning and see what they are up to – gorilla or plant.

You hear plant scientists, botanists, saying all the time they need to study plants in the field or grow them in a glasshouse. Although collections of dried plants (herbaria) are essential for studying the variation over time and space – you just can’t go out and observe enough different plants in different places – seeing the plant grow makes all the difference.

Most of my botanical research has been on algae rather than flowering plants, but the same thing applies. During my PhD I would collect my algal subjects (in this case a thread-like alga called Vaucheria that formed green, felty mats on soil, in streams or in saltmarshes and muddy tidal areas).

I would pick out a few threads and grow them on a jelly-like substance (agar – an algal product incidently) in the laboratory and watch them grow and reproduce. That way I understood subtleties in their biology and could investigate whether individuals that looked different were perhaps just responding to different environmental conditions.

Anyway, it gave me great insights into Vaucheria and helped me identify and classify them. I haven't cultured many of the algae I've studied since and I'm sure I misinterpret features and differences because of this.

So now that I have a coffee bush in flower I can watch the flowers turn into fruits and probably find out a lot more about my favourite food plant (I elevate coffee to the level of an essential food).

Also flowering for the first time in my garden this year is that well known and beautiful Sydney garden plant, the frangipani (Plumeria). We planted two of them three years ago – about the same time as the coffee bush – and they are two are doing their thing over Christmas. In this case it’s a bunch of deep pink and white flowers, opening one or a couple at a time. Each flower also hangs around for a week at least.

So the frangipani has a quite different strategy to the coffee bush which goes for broke and exposes its flowers to willing pollinators all in one hit and quickly. Presumably the big showy franipani is easy to spot by a passing pollinator while the coffee bush needs a mass flowering to attract its pollinators. That said, the frangipani usually has lots of flowers open and visible on a larger plant. Maybe the coffee bush is syncronised with some kind of peak in insect numbers. Maybe...

I'm a mere amateur at this garden observing though. I recently skimmed through a book called 'Seed to Seed: the Secret Life of Plants', published in 2006 by biologist (although the author isn’t entirely satisfied with that term) Nicholas Harberd. It's all about a year in the life of a plant, in this case Arabidopsis thaliana, or Thale Cress, the botanist’s answer to the fruit-fly (I've written two blogs on examples of this role).

In fact the book is more than that – it is much about the DNA, hormones and life history of plants as it is about a tough year for a poor little rabbit-munched Thale Cress. I was looking for evidence of seasonal changes, and support or otherwise for my seasonal classification. Let me just say that it confirmed my suspicion that things are different in Australia.

I haven't come close to observing a plant for as long as Nicholas Harberd but already I'm learning things. I had already noticed of course that frangipanis opened sequentially but I hadn’t thought much of it. The coffee bush is new to me.

There is so much fascinating biology and evolution behind the simple difference between these two plants in flower in my garden. I can’t wait to see what happens next.

Images: the top image is the frangipani in my garden and the middle image the coffee bush flowers now all open together.

A Coffee in the Garden

As anyone who knows me knows, I like coffee. As long as I have a couple of good, strong coffees during the day, life is good. It also good for the local baristas.

So it is exciting for me to see flowers appearing on my very own coffee bush. Outside my kitchen window at home I have a one metre high Coffea arabica. I bought it from the Friends of the Gardens (our 'Growing Friends') a couple of years (maybe three) ago, and this is the first year it has flowered.

The coffee bush is well worth growing in Sydney gardens (although perhaps I'm biased because every time I look at the bush I think of my next expresso...). The foilage is always green and lush. The clusters of white flowers along the main stems are pretty and the berries - whether green or in fully maturity red - are even more attractive.

It seems easy to grow in coast Sydney and doesn't need much added water (although I gather for good fruits, and therefore beans, it might need more water and fertilising). In fact it can grow too easily further north, becoming a week of natural bushland in northern Queensland.

My coffee bush is next to a south-west facing wall and gets full sun for only a few hours in the afternoon. Although coffee crops are mostly grown in full sun, the coffee bush grows naturally shaded by overstorey trees.

The coffee species I'm growing, Coffea arabica, is from high elevation forests in Ethiopia. It came to the Growing Friends via Arabia (15th century), Indonesia (17th century) and possibly West Indies and Central America (18th century) or even India and Sri Lanka (later still).

Coffea is in the huge (7,000+ species), mostly tropical, plant family Rubiaceae. Well known members of this family also grown in our garden are gardenia and coprosma. The easiest way to pick a plant that belongs to the Rubiaceae is to look at its leaves - if they are in pairs, opposite one another on the stem, and with a pair of mini-leaves (stipules) between them, it's quite possibly a Rubiaceae.

As always, there are exceptions... But to me the finest Rubiaceae is Coffea and it has the most beautiful opposite leaves and stipules.

I do think I'll just enjoy my coffee bush for its horticultural merit. I was listening with interest to Simon Marnie (ABC Sydney Radio, Weekend Show) talking a few weeks ago about preparing and roasting your own coffee beans but I have a suspicion they won't live up to my (high) expectations.

The images of are of the first opened flower on my coffee bush, plus a coffee bush in fruit from August last year, in Sydney's Royal Botanic Gardens

Spotty Flowers Survive

Just like dogs, some flowers have spots and other don’t. I’m not sure why dogs have spots but flowers have them to attract pollinators.

In fact pretty much everything to do with a flower is about pollination, preferably moving pollen from one flower to another. Cross-fertilisation, as it is called, is one of the main ways variety is introduced into the genetic makeup of plants.

As circumstances change, the variant most suited to the environment thrives, survives and reproduces. This is how evolution by natural selection works. As Charles Darwin put it, more or less, Nature abhors self-fertilisation.

Many of the odder features of flowers have evolved from competitive evolution with animals. Insects with a particular trait gain extra benefit from a plant, and so thrive and reproduce. Plants with the ability to repel that insect if it’s causing a problem, or to increase the likelihood of it carrying its pollen to anther individual of the same species, will also thrive and reproduce.

A kind of arms war results with quite odd traits evolving such as the development of a 30 cm nectar spur in the orchid flower (Angraecum sesquipedale) illustrated at the top right of my blog.

But back to spots. They appear on the flowers of many species, across many plant families, and have clearly evolved a number of times.

According to a paper in the American Journal of Botany investigating spots on what’s called Beetle Daisy, the prevailing view is that dark petal spots attract pollinators by either ‘intensifying’ the colour and texture, emitting scents, producing nectar, trapping heat, reflecting UV light or creating a guide for navigation. The dark spots may also mimic the pollinator itself, giving the impression of a safe, welcoming flower.

The Beetle Daisy, Gorteria diffusa, has large raised spots at the based of only a few ray florets (daisy flowers are actually a collection of flowers, and what look like ‘petals’ are single specialised flowers). It’s called the Beetle Daisy because the spots were thought to mimic beetles. In fact the main pollinator and attracted insect is a fly.

Meredith Thomas from the University of Cambridge, and colleagues from England and South Africa, studied the development of these spots in great detail. They found that each spot was derived from the fusion of four petals, each with ability to produced part of the spot.

The spots look randomly placed to us and the pollinating flies, but this results from a few predetermined ray florets developing spots and not the rest. Due to the ‘phyllotaxy’ of the flower (i.e. the way and order the bits and pieces in the flower develop, in this case in a Fibonacci series – see earlier blog for background) the spots later appear to be random.

The end result is a flower that looks like it has a couple of flies resting on its petals. All very comforting for the potential pollinator, and all good for the survival of the daisy species.

Image: Image of a Beetle Daisy flower with two prominent spots (the so-called Niew variant) from the American Journal of Botany on-line. For more information see the media release or the full article which is freely available until 17 January 2010.

A Succulent Roof

Instead of digging grass and eucalypt seedlings out of your gutter, you could create a proper lawn on your roof (without trees I’d suggest…). Of course a little infrastructure is needed but there are some pay offs.

An article and media release from a recent issue of ASBS Hortscience, the scientific journal of the American Society for Horticultural Science, lists the gains as “improved storm water management, energy conservation, reduced noise and air pollution, improved biodiversity, and even a better return on investment than traditional roofing”.

I’m not sure what ‘improved biodiversity’ means but I assume more bugs and animals enjoying your roof, as well as the few extra plant species you’ve added.

You do need to select your plants wisely and a common (and tough) succulent called Sedum is coming up well in trials. In fact I saw the sedum roof (pictured above) being trialled at the South China Botanical Garden when I visited there a few weeks ago.

As you would imagine, the depth of soil or rooting material also determines how well the plants survive in this tough, dry habitat.

In a four-year study by Kristin Getter of Michigan State University, the minimum depth of growing material was 7 cm. Any shallower and growth was too slow, while adding more material didn’t improve the results significantly. That said, they do suggest that the deeper the growing material the healthier the plants are likely to be.

Twelve species of sedum were trialled with the toughest being Sedum floriferum, Sedum sexangulare, Sedum spurium ‘John Creech’ and Sedum stefco.

We can all look forward to a green and succulent roof above our heads.

Images: Trialling sedum on the roof of a research building at the South China Botanical Garden in Guangzhou, China.

An Australian Botanical Christmas*

We've been here before, but then Christmas is a bit like that. These notes are from my last chat with Simon Marnie for 2009, from Mount Annan Botanic Garden. I spoke with Angela Catterns about similar matters many Christmases ago...

When Europeans first arrived in Australia they were delighted that they could pick wildflowers resembling bells and bright green foliage covered in red or white flowers to use as Christmas decorations. This was a huge contrast to the bare trees and dormant gardens they had left behind in Europe.

In Sydney, December means bunches of Christmas Bush (Ceratopetalum gummiferum). This shrub produces sprays of white star-like flowers in late spring, which by now are reddened around the maturing fruit.

Scattered in Sydney’s coastal heath – and here in the Connections Garden at Mount Annan – you may also find Christmas Bells, Blandfordia nobilis, with large bell-like flowers – yellow to deep red with yellow tips on spikes to 50 cm tall.

Of course, unlike our early settlers, we no longer pick these wildflowers and you can enjoy these in their natural habitat (Blandfordia is protected in NSW and a licence is required to pick flowers or collect seed, and to sell the flowers.)

Our Friends of the Gardens sell Holly Grevillea (Grevillea aquifolium) from Victoria and South Australia as an alternative to European Holly. It doesn’t have red berries, but this scrambling shrub has lobed, prickly leaves with a Christmas feel! (‘Growing Friends’ raise money for the Gardens, with plant sales at the Sydney site 11.30–2.00 most week days – and through the shop at Mount Annan).

Australia also has its own Christmas mistletoe: the parasitic Western Australian Christmas Tree (Nuytsia floribunda), which produces profuse brilliant yellow flowers in summer. Like all mistletoes, this plant is partially reliant on a host plant for nutrition, attaching itself to their roots. Some people are trying to cultivate this Christmas tree, using grasses and strawberries as companion plants.

So what is the perfect Christmas tree for Australians? Back in 2000, the Wilderness Society tried to register a eucalypt in Tasmania’s Styx Valley as the world’s tallest Christmas tree. The attempt failed; however, as the British Guinness World Records Organisation proclaimed that to be a ‘proper’ Christmas tree, it had to be a spruce (Picea), a Northern Hemisphere conifer.

At the time, Greens Senator Bob Brown disputed the ruling, stating that a Christmas tree is an evergreen tree decorated for Christmas. The eucalypt in this case was lit up each night with a four-metre solar powered star, baubles and 3000 fairy lights.

Australians usually decorate small Radiata Pines (Pinus radiata), also know as the Monterey Pine, which are native to California. They are grown in plantations in Australia and occasionally escape into nearby bushland (in some heathland areas they can become environmental weeds, displacing other species).

On our sites, we have occasionally decorated a few Wollemi Pines (Wollemia nobilis) and they are a pretty good ‘Australian Christmas Tree’, although you need to be careful to keep them watered when you bring them indoors.

Trees used by staff at the Botanic Gardens include Hoop Pines (Araucaria cunninghamii), but a bit prickly for kids to decorate, and gum tree boughs in a bucket of water (which will last a couple of weeks and give your house a fresh eucalypt smell). Also popular are bits of driftwood painted silver or gold, or a dead branch already decorated with lichens (from your garden or friend’s property).

Image: My potted Wollemi Pine before I forgot to water it last year. I have new one for Christmas this year!

*This Passion for Plants posting will also appear on the ABC Sydney website (possibly under 'gardening'), and is the gist of my radio interview with Simon Marnie on Saturday Morning sometime between 9-10 am on 702AM.

The Sneezing Fruit

Clearly I don't really need to give the Achacha any more publicity. At the cinema last night watching 'A Serious Man' (a seriously good and typically obtuse film by the Coen brothers) we saw a long (a few minutes?) and expensive advertisement for it. The Ad finished on the shore of Farm Cove, in the Royal Botanic Gardens, so some benefit will have come back to the Botanic Gardens Trust, I trust...

A few months back, perhaps when the Ad was being shot, one of our staff Clarence Slockee brought in an achacha to my office for me to try. I was impressed. Yet another tasty plant food to add to the menu in Sydney. Although originally from the rainforests of Bolivia, it's being grown in Burdekin, Queensland, so the food miles are not quite so bad.

It goes under quite a few botanical names: Rheedia aristata, Rheedia achachairú, Rheedia macrophylla, Garcinia humulis or perhaps even Garcinia gardneriana, which may or may not be the same fruit. Achacha, although it sounds like a sneeze, is a shortening of the local name of achachairú.

It's in the plant family Clusiaceae (which used to be called Guttiferae), along with the mangosteen, but not the mango.

An internet site spruking the fruit says it has been difficult to grow and this has held back its commercialisation, until now. On the same site you can learn that it is "delicious, refreshing, exotic, tangy, effervescent . . . no wonder the name translates as honey kiss".

On the cinema Ad we see the fruit is egg-shaped and orange, with a tough outer layer that can be pealed back (cutting around it with your finger nail seems to be the way to do it) to reveal an lychee-like inner flesh around one or more brown seeds.

As I mentioned a few postings ago, there are plenty of fruits out there that haven't been grown or distributed commercially so I'm sure we have more taste sensations to come.

Image: from on-line story 'New fruit holds NQ potential' in North Queensland Register.

The Lotus Effect II

The 28 November 2009 issue of New Scientist just arrived on my desk with a nice article about how solar cell nanotechnology is borrowing from the lotus leaf.

"The roughness of the new cells at nanoscales...mimics the fibrous bumps on the leaves of the lotus plant, which help it repel water." As happens on lotus leaves (see previous posting), water droplets form beads on the surface of new solar cells and roll off along with "light-blocking dust".

The Lotus Effect

It's lotus time at the Royal Botanic Gardens. The flowers of the lotus (Nelumbo nucifera) have to be one of the most attractive and cheery blooms in the world. The large pink or pink-tinged petals fall away from that green salt-and-pepper shaker (the one you find floating in your Chinese broth), all against the backdrop of the large water-repelling leaves competing for space in our Lotus Pond.

This year we've added an extra dimension to the display by partnering with the Gardens and Cosmos exhibition (Royal Paintings of Jodhpur) at the Art Gallery of New South Wales. You can enjoy a 'divine landscape', a self-guided walk including the beautiful lotus over the next couple of months, and in January we have something for kids as well.

There are plenty of links between the lotus flower and religion, but best I stick to science. Every time I mention the lotus I talk about the 'lotus effect', so... In a wonderful book called Wildsolutions (Yale Press, 2004) by Andy Beattie at Macquarie Uni, Paul Ehrlich in the US and illustrated by Chris Turnbill, also from Macquarie Uni, the authors talk about the discovery of what is now trademarked as the Lotus Effect.

You may have already noticed that water doesn’t adhere to most leaf surfaces – it forms drops that roll off the leaf (and hopefully onto the ground for the roots to take up). Not only water, but even honey or glue won't stick to a Lotus leaf. Dirt and fungal spores also don’t attach and when a drop of water rolls around the leaf it picks up the debri and effectively cleans the leaf surface. So a Lotus leaf is always dry and clean.

The way this works is that the leaf surface is covered in a very rough surface of tiny wax particles (as small as a thousandth of a millimetre in diameter) and everything that tries to settle on the leaf is repelled by the wax. Apparently, a ‘wettable’ surface can be made more wettable by making it rougher, an ‘unwettable’ surface, of wax or similar, can be made more unwettable by minute roughening (which means even less contact between the water and the surface so the water drop rolls off). Sorry if this sounds a bit like Donald Rumsfeld's known unknowns.

Back in 2004 at least, Professor Barthlott and a team in Bonn, Germany, were developing a range of self cleaning and dirt resistant surfaces based on this principle. For example roof tiles and paints, or even a variation on this idea for coating lenses.

For more stories about the lotus look up the links above and come along to our lotus walks and events. You know its summer in anyone's seasonal system when the lotus blooms.

Image: Lotus from last year's summer display in the Royal Botanic Gardens in Sydney. That's water from our fountain in the background but I like to think it's water being repelled from the leaves!

Watching the Climate Change*

This radio story is mostly about ClimateWatch but also (a warning), a little about seasons too. Anyway, this is how it goes...

The Botanic Gardens of Australia, along with various other scientific organisations in the country, have teamed up with Earthwatch to create an environmental monitoring program for the whole community.

The idea is that you become a ‘ClimateWatcher’, seeking out and recording changes in the world around you. When do autumn leaves start to fall, when do flowers bud, and when do migratory birds appear in your garden?

By accumulating information on regular seasonal events like flowering times, we can start to track and understand the effects of accelerated climate change on our plants and animals.

For Sydney the panel chose Jacaranda, African Tulip Tree, Silky Oak, Illawarra Flame Tree, White Cedar, NSW Christmas Bush, Victorian Christmas Bush and Gymea lily. As you can see, a mix of locals and exotics. There are also three plants being tracked nationally, to be compared with studies overseas – the English Oak, London Plane Tree and Ribwort Plantain.

As you know, personally I think we need to better understand our current seasons and seasonal changes before we can detect the climate change affects. I’m tired of hearing about ‘early springs’! At the moment we just aren’t ‘in tune’ with our environment.

‘Four seasons’ might make for good music, but it doesn’t make any sense in Sydney, Australia. Our plants and animals dance to a different tune. There are six seasons recognised by the Dharawal people, south of Sydney. I’m convinced we have at least five, with ‘flowering spring’ starting in August – or maybe even late July around Sydney – and another season added between spring (or ‘sprinter’ as I’ve called August and September) and an extended 4-month summer.

As we speak, it is nearly the end of what I’ve called ‘sprummer’ (October and November), the changeable, and often windy, pre-summer season.

I’ve tried, unsuccessfully, to reach a consensus with my botanic gardens colleagues from around Australia. Brisbane is supportive of the early spring. Melbourne and Canberra thinks it’s too cold in August to call it spring, even though their wattles are blossoming. Adelaide and Perth feel that peak spring flowering is more September than August. Alice Springs is somewhere in between, and Darwin didn’t know what spring was!

If this is all too hard (or the distance of the earth from the sun and changes in temperature are considered more important than biological stirrings), we could perhaps designate Floral Days – like Wattle Day – for each of these important seasonal shifts. I’d first of all move Wattle Day to 1 August…but that would require regazetting at national level and would my other botanic gardens’ directors support it?

Look up http://www.climatewatch.org.au/ for more information on the community monitoring program, or earlier postings for more about resetting our seasonal calendar.

*This Passion for Plants posting will also appear on the ABC Sydney website (possibly under 'gardening'), and is the gist of my radio interview with Simon Marnie on Saturday Morning sometime between 9-10 am on 702AM.

Image: The Gymea Lily, one of the plants to be monitored by the ClimateWatch program.

What does Darwin have to do with Succulents?

For non-botanical readers, succulents are fleshy plants. Things like cacti, stone plants, aloes and even (for the broad-minded succulent fancier) frangipanis.

Tonight I’m giving my annual talk to The Cactus and Succulent Society of New South Wales. As Executive Director of the Botanic Gardens Trust I’m patron of the society and this is part of my very pleasant responsibility to that society. And as usual, my talk is not really about cacti or succulents, but there is a tenuous link.

I’m going to talk about Charles Darwin and his Garden – both the garden (and glasshouse) behind his home at Downe, along with the ‘garden of plants’ that clothes the earth. As I’ve done before, I’ll talk about Darwin The Botanist.

But for this talk, I’ve added some information taken from this latest issue of the journal Bradleya. Volume 27 is devoted to celebrating Darwin and Royal Botanic Gardens Kew, and includes a short article by Gordon Rowley on Charles Darwin’s interest in succulent plants.

It’s a short article because Darwin didn’t have great interest in these plants, but probably only because he had limited access to them. He collected some cacti from the Galapagos Islands (one species was named after him), studied the movement of plant growing tips (called circumnutation) using at least four succulents, and tested how long a plant could survive without water by hanging an Echeveria from his study roof for four months (it survived and flowered).

I’m taking an Echeveria with me to the meeting as my Kris Kringle gift.

[This is my first attempt to load a posting onto Posterous, which is then meant to feed to Twitter, Facebook and http:/talkingplants.blogspot.com… We’ll see how it looks…]

Valuing Plant Namers

I'm in Armidale on the New England Tablelands, attending (part of) the annual Australian Systematic Botany Society conference. This is a meeting where people who discover, document, classify, relationise (OK, I made that word up - they try to track down evolutionary relationships) and biogeographise (again - this time its about where plants live and why) plants.

There are about 100 people here, from all over Australia, with a smattering from The Netherlands, New Zealand, the UK and the USA. Each meeting has a theme and this one is 'Systematic Botany: from science to society', picking up on the importance of plant classification (that's a large part of what 'systematists' do) to developing foods and other products, making land use decisions, biosecurity and so on. That is, it's important work and these people do it.

I was part of a panel for a workshop about accrediting people who identify plants. There is a concern that some reports being prepared for some of our most important land use decisions include misidentifications. This means information is lacking or misleading, leading to wrong decisions.

Lots of professions have accreditation of some kind - lawyers, engineers, nurses etc. - so it's not so novel. Accreditation might also help value the often extensive expertise and experience that goes into even a single plant identification. The best comparison is possibly a single consultation with your GP or specialist.

There was some debate about whether it might be better to start with a quality assurance set-up or a series of guidelines, then move to accreditation. In the end the society decided to prepare a proposal for the heads of Australian herbaria and ultimately governments to work towards a national system.

The rest of the meeting provided evidence of the talent available in Australia in plant systematics, and the size of the problem we face. Not only is there a lack of recognition (by some) of the skills required to identify a plant, a large chunk of our flora is still undiscovered or undocumented. New DNA techniques give whole new perspectives on the evolutionary tree and lead to changes in names and classifications systems. Lots of exciting new discoveries, and more to come.

I won't list all the topics covered in the meeting - you can find the full program at the University of New England website - but just in one morning yesterday we heard about various of the Australian heaths (now in a subfamily of Ericaceae, rather than their own Epacridaceae), a couple of sedges, a grass, Australian stink lilies (in the family of the Titan Arum), she-oaks and the fringe lily (another of those genera - like the trigger plant - with a couple of species in eastern Australia and a huge wad - about 40 this time I think - in Western Australia.

Image: Given I didn't bring my camera, I've used one of my pictures of Epacris longifolia, a favourite Australian heath of mine and one that grows very nicely in my home garden.