Saturday, February 23, 2013

The Snap, Crackle, Pop Tree

Excoecaria dallachyana
A friend rang me last week to say that her exploding tree was doing it again! She had been out feeding the chooks, and the tree, about 20 metres away, had attracted her attention with its noise. Would I like to come over and hear it?
Well, how could I resist?
The tree was one of the original dry rainforest trees on her property, and was making the kind of noise that could teach Rice Bubbles a thing or two! Its tiny seed capsules were bursting open and releasing their seeds at a rate which made it look as though it was spitting with rain under the tree.

Even photographing them was not straightforward, as some of the little three-cornered capsules on my hand burst as I was holding them in the sun, spitting their three seeds away and knocking the other capsules about.
The tree snapped and crackled for at least three hours that day, and to judge by the quantity of seed it still had, is probably still doing it whenever the weather is warm and dry enough.
The seeds developed from inconspicuous winter flowers like these.

Note the plant’s tendency to have fresh green leaves on old-looking twigs. This helps to identify it in the wild. It grows as a shrub or small tree, usually to 4 or 5 metres, though it can apparently reach 15 metres in rainforest.

This plant isn’t often seen in gardens. Its common names include scrub poison tree, and blind-your-eye. Hardly good press, for what is a very attractive tree with a shiny green canopy. I usually see it in the scrub, where its shape is affected by other close-growing plants. The only garden-grown specimen I’ve seen was a particularly beautiful, well-shaped young tree with dense foliage to the ground.

Its bad reputation comes from its white sap. I doesn’t trouble the skin on my hands, but I wouldn’t risk it on my lips or eyes. There is a story that it troubled timbergetters in the old days, as chopping it with axes caused the sap to squirt about a bit, including into their eyes, resulting in blindness for several days.

I don’t think this plant would be any more dangerous in the garden than plants like frangipani, poinsettia and euphorbia, and common weeds like milkweed (often recommended for growing as a butterfly host) and the weedy little spurges that can be found in every garden. Like them, it would need to be handled with care if being cut or pruned. Putting a potentially harmful plant into a garden is something that should never be done without careful consideration.

Thursday, February 14, 2013

A Native "Meadow"

Native grasslands can be very pretty, as landscape architects around the world recognise with the style they call “meadow gardens”.

 Here's a natural example, growing on Tabletop, the distinctive hill which dominates the view from Toowoomba's Picnic Point.

The “meadow” on Tabletop is dominated by kangaroo grass Themeda triandra, one of our most attractive native grasses. At first glance, it appears to be a natural monoculture. Closer examination, however, shows how rich in plant species such grasslands can be.

In Australia, they typically contain up to half a dozen native grass species. I only noticed three there, but there are likely to be others which I missed on my short visit this week.
Our native grasslands are also contain around thirty small wildflower species, in any given place. I didn’t count the ones I saw on Tabletop, but there were certainly plenty of them.

One  was this dwarf cassia, Chamaechrista mimosioides. Like many of the other small herbs that grow among grasses, this is a butterfly host plant.

This little pink pea is a Tephrosia species.

Grasslands also contain other “grassy-looking” plants. Tabletop boasts sedges, Dianella lilies, and saw sedges Gahnia aspera, like this one.

We would love to be able to grow native grasslands, and there have been many attempts, largely inspired by the overseas fashion for meadow gardens.
It has proven to be a rather difficult style to establish in Australia, however, because of the very many, aggressive, introduced grass species that seem to want to get in on the act. The most successful seem to be achieved by people who begin with already established grassland. Otherwise, close planting, and at least three years of careful hand weeding are needed to establish a result like the one nature has created on Tabletop.
Nature probably didn’t do it alone, though. It would have had a little help, over the millennia, from its Aboriginal custodians  who would burn grasslands annually in the winter dry period. I suspect they would also have weeded out any invading trees, like the wattles which have gained a toehold on Toowoomba’s iconic hill.

Thursday, February 7, 2013

The Plant called “Goombungee”

Typha orientalis, Typha domingensis
In the plant world it is more often spelt “Cumbungi”, but this is the plant that gave its name to our local small town, where it grew in the creek.

Like most water plants, it has spread from its original, unknown, point of origin somewhere in the world, to become a native plant in many parts of it. In Australia it is also known as “bulrush”, and is familiar to us from illustrations of the story of Moses in children’s bibles of British origin, which show a closely related Typha species.(These illustrations may be the result of a misunderstanding. It is more likely that the “bulrushes” of the bible were papyrus plants, Cyperus papyrus, a kind of sedge.)

In the U.S.A, the narrow-leafed cumbungee T. domingensis goes by the common names of cat-tails, or corndog grass. In New Zealand, the robust broad-leafed cumbungee T. orientalis is the native species, and is called raupo.
Both local species of Cumbungi  are tall plants with strappy leaves and robust flower stems. They spread to form large clumps, and are able to grow in water up to 2m deep.They are somewhat difficult to tell apart, as their "bulrushes" look very similar. However,  T. orientalis has wider (3cm) leaves, which are somewhat blue-green, as opposed to the narrower, grass-green leaves of T. domingensis.
The narrow-leafed species tends to be "weedier", being more able to take advantage of temporary water, or wet places where the water comes and goes.  The broad-leaved plant likes a consistent habitat and is generally less tolerant.

Male and female flowers develop on each flowering stem. They begin by looking rather similar – just a velvety coating of green at the top of the stem, with male flowers at the tip, and female just below. The male flowers produce copious quantities of yellow pollen which is spread by the wind. Having done their job, they fall off leaving a bare spike above the female flowerhead, which turns brown and thickens to its characteristic “sausage” shape.
Typha species may once have been a major component of the Toowoomba swamp, before it was cleared and drained by early white settlers to build what is now our inner city. They have also been cleared from many of our natural waterways, in the belief that by impeding the water flow they increased flood damage in surrounding areas. Unfortunately, the flip-side of this clearing has been widespread loss of fertile soil and erosion damage to the banks of these creeks and rivers, as the unimpeded water has flowed so much faster through unprotected drainage lines.
Where they still grow in the wild, cumbungi provide much-needed food and shelter for water birds, frogs, and other wildlife. They are often planted as "reed beds", for their value in cleaning up pollution in waterways and wetlands, or for purifying household grey water. T. domingensis is salt tolerant, so is also valuable in reclaiming saline land.
Despite their usefulness, they are often regarded as weeds because of their vigorous colonisation of farm dams and irrigation channels. One would hesitate to grow such plants in a garden pond, but they can be used for dramatic effect if restricted to strong tubs.
A florist’s delight, cumbungi provide long-lasting strappy leaves and ornamental flowerheads, which must be cut soon after they turn brown if they are to retain their shape as they dry.  If cut when they are older, they will burst as they dry out (releasing their seeds in the house and making an annoying mess).
Typha species are used for food all around the world. The female flowers are edible, raw or cooked, while they are still green. The male flowers shed such a quantity of their yellow pollen that people in various countries, including Australia, collect it to eat. It is very nutritious, and said to have a rich, nutty flavour.
Collecting it is a matter of keeping an eye on the bulrushes in springtime until they reach the right stage of ripeness. It is time to harvest it when a gentle tap causes clouds of yellow pollen to be released. A pair of tall gumboots and a large bowl are the necessary collecting equipment. The pollen can be collected by bending the male flower over the bowl and tapping the stem. Expect a small spoonful per flower.
In traditional Maori cooking, the pollen is used to make a kind of bread called “pungapunga”. A quantity of pollen is wrapped in leaves or sewn into bags made of strips of bark, then cooked in a hole in the ground, in which heated stones had been placed.
A modern version of the Maori recipe advises mixing 500g pollen with ½ a cup of water, placing it in a greased bowl, and steaming it for two hours. Alternatively, it can be simply cooked like porridge, added to rice dishes for colour and flavour, or added to pancakes, scones, and cakes.
The thick white roots are also a food that is produced in belly-filling quantities, and are much used by aborigines who live the traditional lifestyle. The bits to harvest are the white shoots, which are produced in spring and summer. They grow horizontally in the mud, then turn upwards to become a new, leafy reed. Cut at about the time they make the turn, they produce a couple of inches of pleasantly flavoured vegetable which can be eaten raw (but peel it first), or boiled, baked, or microwaved. Further away from the tip, the rhizomes are too fibrous to make good eating. However aborigines extract the starch by peeling them, laying them in front of a fire to cook, then twisting the fibres and shaking out a floury substance.

Environmental weeds of the Toowoomba Region

More and more, we are finding good local information on plants, on the internet.
This site gives us a good description of 56 of our most common weeds, with sensible advice on how to control them.
The information comes largely from John Swarbrick, who was the driving force behind the Friends of the Escarpment Parks for so many years. So we know that we’ll find practical advice based on that group’s long experience with clearing our local weeds, and restoring places of environmental value to their original state.
Co-editor is Kristie Jenkinson of the Toowoomba Regional Council's environment and weed control section.

Friday, February 1, 2013

Hairy Rosewood

Dysoxylum rufum

A moderately large tree of rainforests on red volcanic soils, this lovely plant is most often found between the great Dividing Range and the coast. However it is found in the upper Condamine catchment, and may once have been more widespread in the rainforests in the Killarney area.

The specimen in Peacehaven Botanic Park is flowering at present. The young trees in this botanic park give us a good opportunity to see rainforest flowers at eye level. In the case of the hairy rosewood, a morning visit also allows us to appreciate their fragrance.

The flowers will develop into yellow capsules. They are very pretty, and split open to show red seeds, but are covered with short, stiff red-brown hairs. These make you itch, so should be handled (if at all) with care.

Notice that the flowers are also covered with fine hairs.

Unlike our other local rosewood (Dysoxylum fraseranum) to which it is related,  its timber not particularly valuable. It smells of onions, rather than roses, and is white with just as small core of red heartwood. In the past it was more likely to be used for making packing cases than furniture.

It is a potentially stately shade tree.