Crayfish gardening in the Button Grass Moorlands

Button Grass is not a charismatic species but an interesting one. A couple of years ago I attended a two-day workshop on the Button Grass Moorlands of Tasmania, and came away wiser and mildly attracted to this plain plant.

As I knew already, Button Grass is a sedge rather than a grass. Sedges are usually found in swampy or seasonally wet soils. They are superficially like grasses but subtle differences in their vegetative and reproductive structure.

Moorlands are typically thought of as cold, bleak expanses of heathy vegetation over acidic, peat soils. They can also be quite romantic, in a cold, often bleak, way.

The Button Grass Moorland is a treeless vegetation typically dominated by Button Grass (Gymnoschoenus sphaerocephulus). It seems to be a human-created landscape, over 40,000 years old.

Aboriginal people regularly burnt the area, favouring button grass and not the heathland shrubs and trees. Even the classic moorlands of Britain are controlled by clearing and burning.

Excuse this diversion into zoology, but the Tasmanian moorland is home to a fascinating animal, the terrestrial crayfish. The Tasmanian crayfish is the largest inland crayfish in the world, and has an unusual way of living, burrowing into peat-like soil away from streams and lakes.

There are 34 different species of crayfish in Tasmania, most of them restricted to the island and many found in the Buttongrass Moorlands. These ‘terrestrial’ crayfish dig down to the watertable, or else use their chambers to catch run-off. They aerate the soil and are part of the complex buttongrass system.

Button Grass Moorland is big in Tasmania – with half a million hectares covering about two-thirds of the World Heritage Area in the south-west – but Button Grass occurs up the east coast of Australia. We have some in the Blue Mountains around places like Blackheath and Katoomba, south around Carrington Falls and I think closest to the CBD at La Perouse.

As a vegetation type it’s a bit hard to define so it’s arguable whether we have true Button Grass Moorland or just some vegetation with Button Grass. The extensive tracts in Tasmania are the only vegetation type in the world dominated by a tussock-forming sedge. The peat-like soil is formed by sedges and shrubs rather than Sphagnum moss, although the latter does occur in the same areas.

The soil is acidic and nutrient poor – the Button Grass itself has the lowest level of phosphorus recorded in a plant. (Phosphorus is needed to build DNA and for many essential biochemical pathways in plants, and is typically limited in Australian soils – hence the widespread addition of super phosphate for many years.)

It’s hard to replicate these conditions in the home garden of course, but then Button Grass is not the most attractive specimen except in flower (when the white buttons bobble in the breeze) and of course in the moorlands themselves.

You can see local Blue Mountains Button Grass at Mount Tomah Botanic Garden, in the Bog Garden or Australian Woodland.

Image: A potted display of button grass, with illustrated background. *This posting is from the Radio Archives (November 2007).

Cool Roots

A story for a hot summer's day. A few years ago Angus Stewart was answering a gardening question on Simon Marnie's ABC Sydney Radio Weekend Show and mentioned contractile roots in Gymea Lily. He said they draw the plant down into the soil and are important in helping the plant surviving fires.

Contractile roots are common in many different plants, and not just as a response to fire. They pull a plant closer to the ground, or in the case of bulbs, deeper into the soil.

You can usually pick contractile roots by their wrinkled exterior. At a certain stage in the roots development, some cells expand radially and contract longitudinally. This means that other, less flexible, parts of the root get contorted and wrinkled. It also means the plant is drawn downwards.

In the Australian heathlands, it’s a good idea to have your growing point below the soil surface during a raging fire. So a variety of plants, the best known being the grass tree and cycads, send down a taproot to anchor the young plant and then pull the growing tip a cm or two below the surface. Sometimes the stem itself also gets into the act and contracts a little.

For cold climate bulbs, the contraction into the soil is to protect them from freezing temperatures in winter.

Compare this to some of the Trigger Plants (Stylidium) and other species in the heathlands of Western Australia. If you look carefully, you find a kind of mini mangrove – these tiny plants look like they are on stilts and scared to touch the sandy soil.

In fact they are. The stilts keep the plant cool in summer and away from the waterlogged soil in winter. Around the world you can find larger palms and trees propped up by stilt-like roots in tidal or swampy areas, but almost only in south-west Australian heathlands do you find these ‘micro stilt plants’.

The stilts are special roots initiated from the stem above the ground, and only produced in winter when the sensitive root tip is safe from drying out before it hits the soil. Micro stilt plants don’t do so well in fires, but they like open spaces and establish almost exclusively in the season after a fire – in fact their age can tell you when the last fire occurred.

Image: A Trigger Plant from Western Australia keeping cool with its ‘micro stilts’. *This posting is from the Radio Archives (November 2007).

Weedy teaser

A 'weedy' daisy in eastern Australia known as Cobblers Peg, Pitch-forks or on Lord Howe Island, Teasers, has long been regarded as an introduced species from South America.

Bidens pilosa as it is scientifically named, has usually 3-lobed, hairy leaves, and typical daisy flowers with yellow middle and white ray florets (the bits might call petals – a daisy ‘flower’ is a compound structure of many flowers).

Although it favours disturbed areas and its barbed seeds latch on to any passing animal, one of the scientists at Sydney's Botanic Gardens Trust reckones it may be a local plant taking advantage of a changing environment.

This theory arose from some historical research by plant ecologist Doug Benson. Doug compiled a list of all the plant species collected at Botany Bay in 1770 by Joseph Banks and Daniel Solander, the naturalists who accompanied James Cook on the Endeavour.

Using an unpublished list of specimen material held at the Natural History Museum in London, together with previously unavailable specimens held at the National Herbarium of NSW, there is now a list of 132 plant species collected from Botany Bay between 29 April and 2 May, in 1770.

Among the specimens are many species which still occur in remnant vegetation around Botany Bay. A particularly interesting record is a specimen of Bidens pilosa held in the herbarium.

So circumstantially, it seems likely that this species was here prior to European settlement. It may have arrived and travelled through Australia with earlier migrations or through trading in Northern Australia – it is also found in tropical regions of the world.

It’s interesting to test our definition of a ‘weed’. Put simply, it is a plant out of balance. In this case it may be a native species adapting well to human disturbance. There are certainly other weedy Australian plants, such a few of the wattle species and in some situations sweet pittosporum.

Sorting out the true origins of Bidens pilosa would require DNA sequencing, to compare the genes of the Australian populations with those overseas. We have yet to do this.

Image: A photo of Cobbler's Peg by Terry Tame from our website. You can find out more about this species on Sydney's Botanic Gardens website: see PlantNET or the Botany of Botany Bay site. *This posting is from the Radio Archives (October 2007).

Ah, sweet tobacco!

What kind of drink is nectar? Birds love it, butterflies love it, and people love honey which is made from nectar (we also like things we call ‘nectar’ but are really juice).

My favourite nectar producing plant is the Weeping Schotia (Schotia brachypetala). Every late spring, the deep red flowers of this South African tree drip with nectar. It's just finished flowering in Sydney's Royal Botanic Gardens were it attracts plenty of human and bird visitors.

If there are a few hot days, the nectar ferments, much to the delight of local birds. In Queensland, dozens of drunken Friar Birds have been staggering around the bottom of a Weeping Schotia. Plenty of Australian plants produce copious nectar and may have the same influence on our wildlife.

Apart from its potentially intoxicating effects, nectar provides food for various insects, birds and mammals. Plants typically use nectar as a way to attract pollinators to their flowers.

Nectar contains a lot of sugar, but also additives such as amino acids and vitamins. Quite the fitness drink you’d think.

On the down side, there are often potentially toxic compounds in the mix, such as alkaloid nicotine. A couple of years back, scientists Kessler and Baldwin form the Max Planck Institute for Chemical Ecology in Jena, Germany, tried to get to the bottom of this tantalising drink, and to find out why a plant would risk poisoning the very animals that help it reproduce.

Their studies showed that some of these chemicals were indeed unattractive to flower visitors.

Sometimes the chemicals were selective against animals that raid the nectar but don’t provide any pollinating service. Other times they repelled all visitors equally.

The best hypothesis the scientists could come up with was that the presence of nasty chemicals like nicotine means that less nectar is consumed per visit. This would save resources as well as lead to more visits overall.

Alternatively, their trials were all with a wild tobacco species so maybe nothing in the tobacco plant can be entirely nicotine-free.

Image: The ever popular Weeping Schotia in full bloom. *From the Radio Archives (October 2007).

Beautiful science

Governor Macquarie once said that the Domain was for the ‘respectable class of inhabitants’, and not ‘idle and profligate persons’. This was not an uncommon view in botanic gardens at that time, but fairly mild by world standards.

As I mentioned previously, in April 2011 I head off to Royal Botanic Gardens Kew in London. One of the key figures in the history of that Garden is Joseph Hooker (and his father William) during the second half of the nineteenth century. 

As one of his biographers Jim Endersby (who studied here in Sydney) said “Hooker worked [hard] to attract the public while keeping them out…”.

Hooker maintained the rule of his father that the public could only enter after 1 pm, despite public opposition. Before 1 pm the Garden was open to botanists only.

At the time, the (in)famous zoologist Richard Owen lobbied to have the herbarium at Kew moved to the British Museum so that Kew would be free to entertain the public and do horticultural experiments, such as “the application of manures, or demonstrations of the fittest species of grasses for particular soils”.

Hooker replied that the proposed manuring experiments “would involve an enormous expenditure, and occupy many acres of ground now devoted to the legitimate purposes of a botanic garden”.

In one letter written at the time it was said “Kew has been made so beautiful and so attractive to the public that there was a danger that its immense scientific importance is likely to be overlooked.”

In 1877 Hooker finally opens garden to general public at 10 am, but only on Bank Holidays… Otherwise it will ‘be regarded as a park’ and ‘demands for luncheons, picnics and bands of music will follow’.

A year later he said that due to numbers he might have to restrict access again… The scientific purposes of the gardens would be damaged ‘if swarms of nursery maids and children’ were allowed in before lunchtime.

A London magazine complained that in reality Kew was ‘a snug little preserve…for the scientifically inclined members of the Hooker family’.

In 1882 Hooker moved opening for general public from 1 am to midday…

In 1898, after Hooker retired, his successor (William Thiselton-Dyer, who married Hooker’s daughter, so still in the family…) opened gardens all day to public in summer. Only in 1921 were the gardens open to the public all day, every day….

That delicate and charming friction between recreation and science continues today. Is this a beautiful place or a place or learning? Or heaven forbid, both!

Image: At the top, a sign from the Wuhan Botanical Garden in Central China; just above, a door to the scientific laboratories at Missouri Botanical Garden, St Louis, USA. (This posting is part of an end-of-year speech I gave a few weeks ago at our annual Botanic Gardens Trust Thank-you event.)

If a tree casts a shadow on a distant planet...

A few weeks ago I mused on the possibly very dark coloured flora of a distant planet. Today a report came in from New Scientist that the shadow cast by plants on distant planets would alter the amount of light reflected back to us.

Scientists from the universities of Oxford and Princton reckon one day we'll be able to see from Earth the shadows of trees in other galaxies. Well, sort of.

The New Scientists Rachel Courtland summarised the results of their paper from Astrobiology (DOI: 10.1089/ast.2010.0495 if you are into that kind of thing)

And this is how you see a tree shadow when it's a long, long, long...long way a way. When a planet is behind its star from our perspective on Earth the trees have little visible shadow, but elsewhere in the orbit the shadows are longer, from where we sit. We are asked to imagine this on our own moon.

When it is 'full' it's behind the sun, our star. If there were trees on the moon, they would be dead... Just kidding. Let's assume their is water and all the other things they need. Then, these trees would hardly cast a shadow on the other side of the sun but a big one on our side.

Researchers Christopher Doughty and Adam Wolf reckon telescopes will one day be able to pick up these subtle changes in brightness.

Photosynthetic things, like plants, reflect a lot of light (hence the suggestion in my earlier post that blackish plants would be more efficient than our Earthly green ones). It's noted that one reason for this reflection is to stop overheating - a problem for dark coloured plants and perhaps why they aren't common on our planet, or maybe any other.

Astrobiologists (scientists looking for life throughout the universe) look for planets with a lot of reflected (near-infrared) light. This spike is apparently called a 'red edge' and is thought to indicated plant life. The shadow effects might help distinguish planets dominated by algae (hurray!) from those with more complex, bigger life, like Planet Earth.

Nancy Kiang, who I mentioned last time, says 'the proposal is interesting, but cautions that steep mountains could mimic the effect). The shadow advocates say that even an apparently lumpy planet like Earth has less than 1 per cent of its surface with a slope of 45 degrees or more so the geological shadows won't rival the tree ones.

I have no idea whether this makes sense or not, but I love the idea that we can think about, and plan for, measuring tree shadows on distant planets.

Image: Tree shadows at Mount Annan Botanic Garden (photo by Jaime Plaza), possibly visible from far galaxies.

The leather jacket and other summer fashions*

The Leather Jacket is just one of the plants that surprises us by flowering in mid-summer (and not being a fish or piece of clothing).

It’s an interesting plant, once called Barklya syringifolia but now called Bauhinia syringifolia – i.e. in the same genus as the Hong Kong Orchid Tree. We can call it the Leather Jacket, which I presume refers to the bark which is a rough greyish brown colour in the mature tree.

The medium-sized tree (to about 18 m tall) has leaves a little like the Hollywood or Diamond Leaf Pittosporum (Auranticarpa rhombifolia) which is sometimes planted as street tree around Sydney, but the leaves of the Leather Jacket have seven distinct nerves rising up from the base of the leaves.

The flowers are the colour of the Diamond Leaf Pittosporum fruit, bright orange, and in brushes to 10 cm or so long. So nothing like that plant really, but from a distance they could be confused.

Leather Jacket grows naturally in Queensland rainforests and at one time apparently as far south as northern New South Wales. There is only one historical record from NSW, undated and from near the Richmond River, and it was recorded by Joseph Maiden as occurring in this State in 1904. It’s now grown in gardens in both New South Wales and Queensland.

This is just one of the many plants in flower at this time of year. Another worth seeing is the South African Gardenia thunbergia near the Levi Fountain, or of course hydrangeas and very soon lotus in the pond near the restaurant.

While we tend to think of spring (or my spinter and sprummer) as peak flowering season – which it is – there are always plants in flower in our gardens and the native bushland. In the early 1960s, Doreen Price collated information on 442 garden and native plants growing in northern Sydney and while more than 200 were flowering in spring, nearly 100 of the species had flowers in summer.

Ms Price was gathering information to help treat pollen allergies so the bad news is that there is likely to be pollen around all year. The good news is that in winter only 50 or so species are flowering.

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

Image: A quick snap of the Leather Jacket from my mobile phone from last year.

Ancient Nachos?

The big question is, were nachos popular in ancient times? At least we now know chillies and corn were both readily available.

Chilli peppers come from the Americas, particularly Brazil and the Andes, and didn’t reach countries like India and Thailand until the Europeans visited there after their trips to the Americas in the 15th century.

But in the Americas, from the Bahamas to southern Peru, recent research has found traces of capsicum on the cooking pots used 6000 years ago.

Capsicum is in the family Solanaceae, with tomatoes, potatoes and deadly nightshade, and it includes about 35 species. The spicy, hot compound found in some species is called ‘capsaicin’, produced in fruits to deter seed predators.

But back to these grubby pots. Microfossils of capsicum starch grains were found on ancient grinding stones and cooking pots.

Starch grains are microscopic storage granules found in plants. It turns out they show a great variety of shapes and sizes, although to the untrained eye they look like ill defined clusters of blobs.

In many plants, the starch grains are unique for a particular species or cultivar. In capsicum, they can also be used to distinguish between domesticated and wild varieties. The capsicum grains on the ancient pots were from five different domesticated plants.

The fact that no starch grains of wild species of capsicum were found near the sites examined indicates that domestication occurred long before the sites were occupied.

Starch grain analysis is becoming a popular technique for recovering and identifying microscopic fragments of plants from fossil sites. It has showed, for example, that many early crops were domesticated in the lowlands of the American tropics, rather than in the highland regions as previously assumed.

Archaeological preservation of plants occurs more readily in dry, arid areas such as the highlands, and it was only with the advent of starch grain analysis that the tropical residues could be identified.

The starch grains also tell us maize was the only other plant present at all the sites sampled, so perhaps, just perhaps, nachos were an ancient staple (as far as I know, cheese making doesn’t leave starch grains).

Image: One of Warwick Orme's luscious Capsicum images. *From the Radio Archives (September 2007).

Nothing punny about Kew

It’s about time I blogged on my imminent move to Royal Botanic Gardens Kew.

Given the confusion caused by the Sydney Morning Herald headline ‘The Life Botanic Leads to the Head of the Kew’ I’ll avoid puns. (The ‘the’ is critical here in that I may well have moved to the head of a kew/queue but not exactly to the head of kew/Kew. Get it?)

Still, the job I’m heading off to is big and exciting, to me at least. It’s called Director of Conservation, Living Collections and Estates.

I’m part of Steve Hopper’s Executive Board. Steve is a fellow Australian, from Perth, and CEO of Royal Botanic Gardens Kew.

My responsibilities include the botanic garden at Kew (its plants, landscapes and structures), the botanic garden at Wakehurst Place (ditto), the Millenium Seed Bank (at Wakehurst Place), infrastructure generally and conservation programs. I look after about 400 of the 800 people who work at Kew – the rest are in the Herbarium, Library, Scientific laboratories at Kew (the Jodrell Laboratory), Visitor and Corporate Services.

At least that’s a rough cut, from what I understand. I’ll tell you more after I start there on 27 April 2011 (that’s two days before the Royal Wedding…). I finish at Sydney’s Botanic Gardens Trust on 25 March 2011 (that’s the day before the New South Wales State election – it just happened to be an easy day to remember!).

So why move? Firstly, there is plenty to do at the Botanic Gardens Trust in Sydney and it remains one of the great botanic gardens in the world. Leading up to 2016, its bicentenary, there will be plenty to keep the new Executive Director busy. I’ve thoroughly enjoyed the job, and particular the chance to spruik plants, science and gardens (I hope to apply these spruiking skills to my new realm).

But, the pull of Kew is strong. With its fascinating history, powerful scientific team and incredibly rich collections (I think 6 million or so plants and fungi in the herbarium and something like 30,000 species growing in the ‘living collections’) it is very much a world-focussed botanic garden. And then there is the Millenium Seed Bank, the international conservation programs, the steady stream of botanists who pass through, the access to Europe (its gardens, nature and culture).

The weather? Well I’ll finally find out what it is like to have seasons :). The economic climate? Yes tough times ahead but I’m looking forward to making sure Kew Gardens comes out of this in good, or even better, shape. There is a lot of maintenance to do, but also lots of exciting plans.

It will be fun living in London for a while, with ready access to London music scene, English countryside and…Paris. Living in Kew Gardens is enticing, despite the flight path and perhaps being just a little too close to work occasionally. All in all, though, an thrilling adventure for Lynda and me (the kids – Jerome and Emily – plan to visit, on their way to various holiday destinations).

Enough for now. I’m here in Sydney, and blogging, until March. The big decision now is whether to convert ‘TalkingPlants’ to a Kew-centric blog or to leave something Australian focussed back here in Sydney. Rest assured, I’ll be blogging from Kew in some form or other. I might even find other ways to provide A View from Kew… Stay tuned!

Image: I won't have Grey-headed Flying-foxes at Kew, but there are Canada Geese.

Australian heaths reunited with overseas relatives

When I was taught botany, the Australian heaths were thought to be closely related but quite distinct from those found in the Scottish moors or the South African fynbos. Ours were classified in the family Epacridaceae, theirs in the Ericaceae.

We had most of the world’s Epacridaceae – including things like the local Fuschia Heath (Epacris longifolia) – but only one native Rhododendron and another half a dozen or so species in the Ericaceae family.

OK I was educated in Melbourne, and this was a long, long time ago, but I many of us still think this is true.

As discussed with Simon Marnie a few years back, things are different now. Not only have we doubled the number of native Rhododendron species (from one to two…), but DNA evidence shows that our Australian heaths are embedded within the bigger Ericaceae family.

There was bit of confusion for a while about the name of the new Rhododendron species, but it’s now accepted we have Rhododendron viriosum from high-altitude rocky outcrops around Cape Tribulation, and Rhododendron lochiae (also called for a while Rhododendron notiale, but let's not go there) from similar habitats on the Bellenden-Ker Range. Both are rare, and you can see the former – with its straight rather than curved floral ‘trumpet’ – in the Rare and Threatened Garden at Sydney's Royal Botanic Gardens.

In the new family tree, our native heaths are nestled in with the rhododendrons of China (and those two from Australia), the heaths (Erica) of southern Africa and the heathers (Calluna) of Scotland. Their closest relatives turn out to be the blueberries, a cluster of plants including true blueberries (Vaccinium) from all over the world, and the waxberries (Gaultheria) from Australia, New Zealand and South America.

However all is not lost and we can still retain some national pride. Because the southern heath genera have a common and unique ancestor, they will form a distinct subfamily, called the Styphelioideae (within the family Ericaceae).

If you ever need to separate the ‘epacrids’ from the rest of the family Ericaceae, the leaves usually have parallel veins and the flowers produce as many stamens (the male bits that shed pollen) as petals. There are also some more obscure characters that support the grouping, such as thickenings on leaf epidermal cells and the mechanics of pollen release. And of course there are the genetic similarities.

Image: One of our two Australian species, Rhododendron viriosum, in the Royal Botanic Gardens. *This story is based on one from the Radio Archives (May 2007).

A prickly issue

In a cowboy film shot in Mexico, you’d expect to see a few cacti in the background. But if you see anything looking like a cactus in a spaghetti western – mostly shot in mainland Spain, but sometimes the Canary Islands or Africa – it will be a euphorbia, not a true cactus.

Cacti and succulent euphorbias don’t grow together in nature, but the great thing about a garden is you can grow them side by side.

Cacti are only found naturally in North and South America, with some spread in more recent times to places like India, Africa and in the case of Prickly Pear, Australia.

The euphorbia’s family is much more widespread, but the succulent ‘cacti-like’ euphorbias are mostly from South Africa. Euphorbia’s exude a white, poisonous milk that protects them from insect and animal grazing in their native habitat, and the flowers are simple without the showy petals of the cactus (although sometimes with colourful bracts).

This is a good example of how the environment, in this case a hot, dry climate – results in similar adaptations. This is sometimes called convergent evolution, where things with quite different ancestors end up looking similar (e.g. the dolphin and the shark).

In this case, the cacti and some Euphorbia’s have become stout and fleshy, with a tough outer skin, all to reduce evaporation. There are plenty more of these ‘succulents’, including a nice geographic analogue with agaves and aloes, with their rosettes of chunky leaves.

The agave grow in the deserts of Mexico and Central America with the cacti. Their leaves are very stringy inside – these fibres have been used to make ropes. The spines are sharp.

An agave plant flowers only once, then it will gradually die. As it dies, a sucker or a new plant will be produced from its stem. The giant Century Plant (Agave americana) is a good example, although it tends to flower in 25 rather than 100 years.

The aloe shares the African continent with the succulent Euphorbia’s, particularly in the south provinces. If you break open an Aloe leaf you’ll find a jell-like flesh and yellow sap. The spines, if present, generally won’t break the skin. Aloes flower seasonally, mostly in late winter through to spring, but with some occasional flowers year-round.

By the way, the sweet juice of some agaves is used to produce a kind of wine called ‘pulque’, or distilled to make ‘tequila’, while the juice of the aloe contains a purgative and was once thickened into a brown resin for use in embalming.

There are lots of other plant families with some or many species succulent, such as the stone plants and pigface (in the Aizoaceae family, with their daisy-like flowers but unrelated to the daisy family), gasterias and haworthias (in the aloe family), and stapelias (Ascelipidaceae, the milkweed family).

Image: An aloe in flower, in winter, in the Cacti & Succulent Garden at Sydney's Royal Botanic Gardens. *From the Radio Archive (July 2007).

Wild rice is both rice and grass

“Wild rice is not rice, but a grass” said  a commentator on the (original) Iron Chef, on SBS TV. This is both right and wrong.

Keen followers of my botanical ramblings will remember I wrote about this some time back in an issue of the Friends of the Gardens' magazine The Gardens, and also spoke about it on air. To celebrate the Australianisation of Iron Chef (to which I haven't quite connected) I repeat here my brief investigation into the origins of rice, wheat and corn.

Rice, wheat and corn are all seeds extracted from a member of the grass family Poaceae. So technically they are a kind of grass.

Rice was first grown in agriculture some 7000 years ago, in China. Since then it has been continually selected and propagated to produce the high yielding crops in cultivation today.

Common rice, eaten by at least three billion people every day, is a cultivar of Oryza from Asia or Africa.

Wild rice is not an ancestor of common rice, but comes from the closely related Zizania, a mostly North American genus. Like common rice it grows best in wet areas. A species of Zizania from China, called Manchurian Rice, is now rare in its natural habitat. It grows well in cultivation – in fact so well that (like many other plants and animals) it has become an invasive species in New Zealand.

So wild rice is a bit different to regular rice, and both rices are grasses…

Wheat has a complex origin. It was bred from a mix of cultivated Triticum and weedy Agropyron species growing in Mesopotamia over 8000 years ago.

Corn (or maize) comes from Zea mays, bred from species that grew naturally in Mexico. Domestication of corn also began 7-8000 years ago.

We don’t have rice or wheat growing in our Gardens, but we do have commercial corn in our Cadi Jam Ora/First Encounters garden.

We also have one of Corn’s purported ancestors, the high altitude corn Zea mexicana, in the Rare and Threatened Garden in Sydney's Royal Botanic Gardens. Teosinte as it is commonly called, has small ‘ears’ with only a handful of kernels, each protected by a tough outer shell reminiscent of the closely related Job’s Tears (Coix lacryma-jobi). Thousands of years of breeding removed the outer shell, and pumped up the volume of the grain.

Image: The original corn with its small ‘ears’, and kernels encased with hard shell, growing and fruting in Sydney's Royal Botanic Gardens. *This is based on a story from the Radio Archives (June 2007).

One part lion’s fat, one part python’s fat and the roots of an upside-down wisteria*

We all love Wisteria, particularly when it’s taking over someone else’s house or wall. But there is no denying its beauty in full flower.

We have plant in Sydney's Royal Botanic Gardens with similar sprays of purple flowers but it’s a tree rather than a rampant climber. I've written before about the Tree Wisteria, Milletia grandis. It grows near the Henry Lawson Gate, on the Mrs Macquaries Road side of the Gardens.

When it’s in flower, as it is now, you won’t miss it. Like many of the subtropical trees in the Botanic Gardens it’s a late spring or summer flowerer. This one is from Africa.

Milletia is in the same plant family as Wisteria, the pea family, but it’s a different genus. It includes about 150 species from the tropics and subtropics.

It was named in honour of Charles Millet, who lived in Canton, China around 1830.

Milletia grandis is from the warm coast forests of Natal through to Transkei in southern Africa, where it is also locally called the Ironwood or Umzimbeet.

The wood is popular for making furniture and these days, two-toned walking sticks, which are popular with tourists. The plant also contains some chemicals useful to local people.

Ground up seeds of Milletia grandis are soaked in milk to remove toxins and then used as a remedy for roundworm.

The roots contain a tranquiliser which is used to encourage sleep. In fact the roots are ground up to help catch fish which must be then boiled before being eaten!

There a nice recipe on a site called PlantzAfrica.com (maintained by the South African National Biodiversity Institute). Simply mix the roots of Milletia grandis and another local plant, the Croton, with one part lion’s fat and one part python’s fat. You then burn this in your house to ‘dispel worries’. (I expect most of the worries come from catching the lion and python in the first place…)

Like the Wisteria, the leaves are what we call pinnate, with pairs of ‘leaflets’ in a row. The flowers are a similar lilac or purple, but the clump (or inflorescence) is directed upwards rather than drooping down. It’s worth a visit to see this plant in flower, and to imagine what you do with a little lion and python fat.

Image: I've used this one before and you see a few others in these posting. They are all from the tree near Henry Lawson Gate.

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