Friday, August 28, 2009

The Most Beautiful Bush Fragrance

Pittosporum undulatum
Sweet Pittosporum is a shrub or small tree native to the dry rainforest and scrubs on our red soils. It is just coming into flower now - a little early, as most things are this year - and the scent carries for many metres.
It’s a popular garden plant. In America they call it "Mock Orange". Fragrant oil extracted from the flowers has been used in perfumes.
When the flowers have finished, they are followed by pretty fruits which look like little oranges, but split in two to reveal bright red, bird-attracting seeds inside.
Although it comes up naturally in Toowoomba gardens, it is, sadly, not grown here as much as it should be.
Part of the reason is that, outside its own territory, it has the potential to become just as much of a weed as privet does here. (Yes, Australian natives CAN be environmental weeds!) I find it depressing, though, that in a country which learns more about its native plants from books and television than from going out into the bush and seeing what’s there, local “experts” parrot what they’ve learned from Sydney and Melbourne sources and advise Toowoomba people against this local native plant because it is “weedy”!
It is nothing of the sort, here in its home territory.
Yes, it does self-seed. This is what native plants SHOULD do.
No, it doesn’t self-seed to an extreme or nuisance extent.
Meanwhile, considering its rainforesty appearance, it is astonishingly tough, surviving in open paddocks where it is fully exposed to all that the climate can toss at it. Stock find it a very edible plant, so tends to survive there only along fence-lines or tucked up against posts, where it has some defence against being munched to the ground. Like most woody fodder species, it will respond to pruning by growing as a dense bushy shrub - a useful garden quality.
Sweet Pittosporum is a perfect plant for a waterwise suburban garden, where it can be left to grow as a little tree, or kept shrub-size for a screen or bird-shelter, or to fit into your plans for a garden picture. Its deep roots are happy to share with others, so it grows well under existing trees.
It is used in some parts of Toowoomba as a street tree, something for which it is very well suited, as it has the toughness requirement but never gets too tall for the power lines. (Heights of rainforest trees are very variable. In dense rainforest, this tree can reach 12 metres, but grown in the open it would be doing well to get to a third of this height.)
This is one of the many dry rainforest shrubs that can be purchased for $2.00 from the Crows Nest Community Nursery.

Planting in a Drought

Isn’t this weather miserable! It’s the hottest, driest August I can remember.
But yes, you can plant trees and shrubs now.
Get them in before the summer’s heat, look after them well, and they’ll reward you with a season’s growth before winter.
First, choose plants with drought-resisting potential - and it’s amazing how many of them there are. The local native plant species of our dry rainforests and scrubs are among the best, cheerfully putting out lush green shady foliage despite years of drought. They have evolved to do this by developing roots which can grow rapidly downwards, to a depth far exceeding the height of the tree’s canopy.
To create a drought hardy plant, you need to get your juvenile plant away from the "lolly shop” - that top layer of soil where "spoiled" plants develop shallow root systems. Don't mollycoddle your plants with surface watering. They grow roots where the water is, then suffer badly when the topsoil dries out.
Toughen your little plants up by teaching them, young, that life wasn’t meant to be easy! You can do this with a watering technique which gets the water down to the root zone and below it, skipping the top layer of soil. Young plants then learn to reach deep, and eventually they’ll find the natural groundwater, becoming quite independent of what is going on in the top metre of soil.
Planted straight from little tubes, these species can survive if you simply dig a deep hole, fill it with water and let it drain away, put well-soaked water crystals in the bottom then arrange the plant with its roots reaching down as far as they’ll go, their tips just touching the top of the crystals.
The roots must be straight. If you think they might have curled around in the bottom of their pots, de-pot them, soak them in a bucket of water( in the shade), and wash the soil off. This treatment will kill Australian plants such as Grevilleas, but rainforest-type plants are perfectly happy to be treated this way, so long as they’re kept wet in the process and the hole is filled with wet soil.
Arrange the soil surface in a bit of a dish so any rainwater will run inwards to the plant, or with a run-off-catching crescent mound, if it’s on a slope.
Mulch well
with organic materials. Think about keeping the soil cool. If temporary shade for part of the day is easy to arrange, do it. Do you have leftover firewood that you can stack to the north and west of the plant?
This may be all you ever need to do.
However, if the weather - particularly this warm dry wind - continues, the plant should be watched for signs of wilting. If no rains come after a month or six weeks, an extra dose or two of water may be needed to keep it alive while the roots are still small. A good soak, leaving water to sit in the dish, will re-charge the crystals so that as the soil dries out again, the plant will once again find itself in dry topsoil but with water deep down where it counts.
Plants treated like this will survive, and grow when rains give them the opportunity.
However, all plants grow much faster if given generous amounts of water at an early age.
For maximum growth on minimum water, a good planting technique is to use a large plastic bottle with a hole in the bottom. Bury it beside the plant as you put it in. Water can be poured into the bottle, where it will soak in below the little plant’s roots, leading them downwards.
If you have heavy clay where the bottle takes a week or more to empty, bless your luck in having such water-saving soil, and put the lid on the bottle to stop mosquitos from breeding in it.
With this technique, nothing whatever is wasted to evaporation. Even mulch becomes unnecessary once the plant’s roots get below the top foot or so of soil. This top soil layer then becomes the mulch.
Rainforest species appreciate a little fertiliser every now and again. Ordinary fertiliser will do. Unlike Grevilleas and some other Australian plants originating in naturally low-phosphorus soils, rainforest plants don’t need special “native” fertiliser.

Friday, August 21, 2009

King Orchid

Dendrobium speciosum subsp. hillii
(Dendrobium tarberi, Thelychiton tarberi)

These popular orchids are flowering all around the district at present, with many to be seen in Toowoomba gardens, typically planted in the hollow centres of old tree stumps. The sturdy stems (pseudobulbs) are usually about 40cm long, and at this time of year the plants put out magnificent drooping spikes of as many as a hundred small, creamy yellow, and very fragrant flowers.
There are about half a dozen subspecies of Dendrobium speciosum. Some of them get called “Rock Lily” or “Rock Orchid”. The name never took off in our part of Queensland, as our local subspecies prefers to live on trees, often in rather high, exposed situations. A favourite habitat in the wild is on the Hoop pines which tower above the canopy of our local dry rainforests and scrubs.
This plant is so easy to grow that it could fairly be described as a “beginner’s orchid”. All it needs is a well-drained, sheltered site (where it gets direct sunlight for part of the day), and a bit of water while it’s getting established. After that, it will survive neglect, drought, and all but the worst bushfires.
It likes being watered, of course, but plants which find themselves in damp sites have the rather weird habit of sending their little fresh roots straight upwards, seeking drier air.

Orange Blossom Orchid

Sarcochilus falcatus
This local native beauty is regarded as one of the loveliest orchids in the world. It has been flowering for several weeks, now.
The dainty plants are only small, but the spring racemes of 2.5cm flowers punctuate the shade of the vine forests with white, and have a strong, sweet perfume.
The plants are epiphytes, growing naturally on tree trunks and branches small and large, and on mossy boulders in the cooler, higher parts of our district. They like well-lit exposed situations, and prefer a climate that’s a bit fog-prone.
Sadly, this plant is rarely seen in the bush nowadays, as it is possibly our most-stolen of the native orchids. It’s now almost extinct in the wild.
It's a bit touchy to grow, but the rewards are worth it. It survives dry periods by becoming quite shrivelled and stressed-looking until the next rainfall.
It likes good light, but almost no direct sun, and is best watered at least once a week, all year round.
These plants are usually grown on a mount, but could be naturalised on trees in the higher rainfall parts of our area.
They like to be grown in light shade, and good air movement is particularly important.

Where to buy Native Orchids.

The displays put on by Toowoomba’s Orchid Societies during the Carnival of Flowers are great fun to look at, of course, but also have SALES. Here's the place to pick up bargains, as well as rare plants which are otherwise difficult to source.
This year, the Native Orchid Society’s display will be held at the Milne Bay Military Museum, (Cnr Anzac Avenue & O'Quinn Street Toowoomba), from Friday 18 to Tuesday 22 September. They are always an excellent source of Australian orchids of all kinds, including some very desirable local native species.
Our other two orchid societies display orchids from around the world, but there are always some natives for those of us whose interest leans that way.
The Toowoomba Orchid Society’s display will be in the St Paul’s Church Hall on the corner of Philip and James Streets from Friday 18th.
The Darling Downs Orchid Association’s display won’t be open until Saturday 19th, at Centenary Heights State High School Assembly Hall, corner of Ramsay and South Streets.
So if you think you’d like a good display of orchids at home next year, save your pennies, and get the plants next month.

Thursday, August 13, 2009

Wattles - Evolution in Action

Wattles - Evolution in Action
Australian acacias had a problem. Their leaves were costing them too much. Plants lose water through their leaves, and as the continent dried out they were being pushed to the wall. A few million years ago, as the ice age advanced and climate change cooled and dried their home ground, the situation became serious. Something had to be done - but the trouble is that plants need those green leaves, to do the essential job of photosynthesis. They capture carbon dioxide and remove the oxygen from it, thus providing the plant with its “food” - a steady supply of carbon.

Typical wattle leaves.
The common local Cinnamon Greenwattle

Acacia irrorata

What the wattles needed was to develop a new way of photosynthesising, so they could get rid of those water-wasting leaves.
Changing the nature of the leaf-stems - the petioles - was the answer. In many species of wattle they became longer, broader, flatter, and full of green chlorophyll, the substance which is essential for photosynthesis. The wattles could then give up making leaves, and hey presto, here was a whole new suite of drought-hardy plants!

Leaf in Transition.
Oleander-leafed Wattle

Acacia neriifolia

Not all wattle species have done it. Some still have leaves, just as their ancestors have always done. We sometimes see them described as the “ferny-leafed” kind of wattle. The others are called “long-leafed”. In reality, they are completely leafless, but their modified leaf-stems, (which botanists call phyllodes), look so like leaves that the difference can be hard to detect.

Growing up. Three leaf-types on one branchlet, Acacia neriifolia

We can still see the evidence of their evolutionary history, though, in young plants. Wattles of the “long-leafed” type begin life with ferny leaves. Then, as they grow, leaves with exaggerated stems appear. The tendency to produce leaves soon disappears, and older plants have nothing but phyllodes.
The toughest, most drought-hardy wattles produce just one leaf, then get down to the leaf-free life as soon as possible. Others, such as Acacia neriifolia, go on producing the half-and-half model until they are more than shoulder-height.
They are a common local plant, so we can see plenty of examples in our local bush. If you want to see some, look for seedlings among the adults which are
looking so spectacular along the top of the range at the moment.

Some wattles evolve even further. Their phyllodes hang vertically, so as to present the least possible surface area to the sun - and their colour has changes to silvery grey, to reflect sunlight. These very tough plants waste little of their lives producing leaf - a single token leaf at birth is all they bother with, before getting on with producing phyllodes. This brigalow (Acacia harpophylla) at right is a typical example of these most drought-hardy wattles.

Oleander-leafed Wattle

Acacia neriifolia
A rather imaginative person once thought that the narrow phyllodes of this plant resembled oleander leaves.

Be that as it may, this fast-growing, 8m tall plant is one of our district's best wattles,  having a spectacular display of golden flowers in August. Each year, they make a magnificent show on the road between Toowoomba and Crows Nest.

In the bush we see it as a smallish tree, with most of its flowers high out of reach. If used in a garden it responds well to pruning, so can be kept as a shrub. Pruning increases its bushiness, making it a good screen and Oleander-substitute.

Most people don't prune their wattles, though, and species like this one which grow fast and are naturally rather large, but are not long lived (about 15 years), are not popular in gardens. For this reason, we need to encourage its use in suitable spaces - beside highways, in drainage easements, in nature reserves and parks, and on privately owned "acreage estate" residential blocks. If its population is allowed to dwindle, as is happening with so many of our local plants as our suburbs spread ever outwards, our district's character will lose something very important!

Unlike the poisonous, non-Australian oleanders, this is a plant which fits the environment. It hosts a rich population of native insects including some lovely little butterflies, and attracts birds which appreciate the insect supply.

This is a wattle for well-drained soil, such as the snuffy red-soils along the top of the range, and the nearby sandstone soils.

It is frost-hardy, and thrives  through the worst of our droughts with no supplementary watering.

A Drive to Crows Nest

This is something Toowoomba people love to do at this time of the year, when the wattles along the highway are truly spectacular. The species you’ll see most of is the oleander wattle, Acacia nerifolia.
On the way, you can look at the marked trees of “Cathedral Drive” near Hampton, and see what the fuss is all about. There are about 1400 of these trees. They were marked with yellow spots and crosses by the Main Roads Department a few months ago. They planned to remove them for roadworks, aimed at making this accident-prone section of highway safer.
A local action group, which considered that the number of trees earmarked for removal was excessive, has gone along and tied conspicuous pink ribbons around some of the yellow-marked trees, making it easy for passers-by to visualise the scale of the proposed destruction. The group considers that the beauty of this drive has economic importance to all those involved in tourist-related industries, from Toowoomba to Crows Nest. Many of them also just like living somewhere beautiful, (and there’s no doubt that destruction of natural beauty in an area affects residential property values). Cathedral Drive would be providing habitat for a lot of wildlife, especially in those tree hollows, too.
As recent events have shown us, this stretch of road is unsuitable for drivers who are not concerned with enjoying the landscape as they drive, but just want to get where they’re going as fast as possible. We tend to take it for granted that highways should serve this function, Here is a piece of highway which does not.
The roadworks project has apparently been put on hold which the issues are worked out.
Continuing the drive to Crows nest, you can see, north of Pechey, the Main Roads idea of suitable clearing, and a highway which has been made "safe".
Like me, you’ll probably find yourself peering at the steep slopes they’ve created on the highway edges, all unprotected by any sort of railing, and wondering....
Much of the new highway was created from road which was once tree-lined. How would you rank it now - on a scale of 1 to 10 - for landscape beauty?
If you feel strongly about the issue, you might like to time your drive so you can call in at the rally which is to be held at Hampton tomorrow (Saturday August 15.)

Hollow trees and Dropped Limbs

Rubbish - or Environmental Riches?
With the Cathedral Drive issue we are, once again, hearing the argument that hollow trees are “rubbish”, so might as well be cleared.
Wildlife - and those who value Australian fauna - don’t agree, of course. To them, trees only start to get valuable when they start forming hollows. The problem of tree removal is not one that can be simply solved by planting new ones. It will take them about 100 years to start forming hollows. Species can go extinct while they wait!
(Don’t let this put you off planting, of course.)
Big old Eucalyptus trees are often hollow. Despite this they have a lifespan of 300 to 500 years, and may stand for several hundred years more. There are still plenty of dead trees standing firm and tall in our paddocks, and showing a telltale ring around the trunk. They were probably killed by ringbarking around 1860.
As engineers explain to us, a pipe is almost as strong as a solid steel post.
Dropped limbs are part of the hollowing process. The stump of a dropped limb makes the best nest for all kinds of native birds and mammals.
As it drops, though, the limb isn’t so popular with humans! Most large species of Eucalypt are a dubious choice for suburbs, and have no place in any but the largest of gardens. And as plenty of drivers who use Cathedral Drive will verify, they can be dangerous when they hang over roads - especially roads where people want to drive at 100kph, so might not have time to avoid a dropped branch.
Not all Eucalypt species are widow-makers, however. If you want to plant a potentially big one near buildings or roads, you should choose one of the better-known timber species. The strength which makes them good for building also lets them keep their limbs on.
Many of Australia’s best-loved and most beautiful trees are Eucalypts of the limb-dropping kind. As the world grows ever more crowded, land use is needing to be more carefully planned. Let’s hope there’s space, in the planning, for lovely old gum trees.
(See the article posted 6 June last year for more on the value of hollows in trees.)

Friday, August 7, 2009

Monkey Rope

Parsonsia straminea
The monkey rope vine is probably the most common vine in our district. It’s not a showy plant, but its virtue (apart from being one of our most characteristic natives) is of being a very tough green-leafed vine which would cover trellises and create shady pergolas with no fuss at all. Vines are typically rainforest plants. Many of our locals are also at home in dry rainforests. Few of them, however, are really happy to be growing in full sun, unperturbed by our district’s frosts and droughts.
This well-known old vine is a landmark at Highfields. It is in a paddock on the eastern side of the highway, just north of the Danish Flower Art shop.
Who knows how old it is - but it would certainly have been there long before white settlers appeared on the Darling Downs.
It would have begun life, as Parsonsias do, in a spot where it was lightly shaded by surrounding trees. It began to climb a tree trunk - perhaps on a long-vanished tree - using the little roots it put out at each node, and making a pretty pattern with its paired leaves.
When it got high enough to find some branches, it gave up the root-climbing habit, and began to climb by twining its stems around the branches instead.

The shiny leaves are so attractive and the plant so trouble-free and easy to grow that it should be one of our local garden staples. Monkey ropes can be found on all sorts of soils, from poorly drained clay soils and alluvial river flats to stony hillsides.
The flowers occur throughout the year. The flowers are sparse, small and inconspicuous, but have a lovely perfume. They attract butterflies, some of which also breed on the leaves.
The woody, pencil-shaped seed follicles turn brown as they ripen, and split open to release a cloud of little seeds, which float away on their little brown silk parachutes.