Friday, October 28, 2011

It’s Wildflower Time

Swainsona queenslandica
I visited a most delightful property, last weekend, at Ramsay.
I always enjoy this time of the year when flowering herbs come into their own. In this case, the plant which made the property outstanding was the Darling pea, Swainsona queenslandica.

I am familiar with the species as a plant that is very common just west of Toowoomba, on the stony hillside black soil (sometimes called “chocolate soil”). It also introduced itself to my own garden on the red soil.
It gets mistaken for another Darling pea, Swainsona galegifolia, but can be distinguished by its wings, which are about the same length as the keel (unlike those of S. galegifolia which are only 60% of the keel’s length.)
It also has the habit of spreading by underground rhizomes, whereas S. galegifolia has a clump of semi-woody stems, all sprouting from a single crown.

My plants, and those west of Toowoomba, are bright, lipstick pink.
(See article Sep 2008)

Those I saw last weekend at Ramsay, south of Toowoomba, are orange-red. This photo shows the root structure, and the rhizome which connected this section of plant to another set of flowering stems.

They seem to be the perfect colour for accent plants in a bushland scene. I found I coveted them for use in shrubberies, to be seen from a distance, and felt very privileged to be allowed to take some of them home.
The interesting thing about the plants on this property was that in one case, they seemed to be suffering from an identity crisis, and were coming up pink. Clearly, the pink and the red forms are very closely related indeed.

Killing Typhoid Mary

I found myrtle rust in my garden yesterday.

We knew it was coming, of course, and I had been keeping a special eye on my brown malletwoods (Rhodamnia dumicola).

Although almost all members of the myrtle family (Myrtaceae) can potentially be affected by this nasty disease, I was aware that my malletwood is one of the most susceptible species, likely to be my “miners’ canary” for myrtle rust.
Having seen the new disease a few months ago in a nearby suburb (see posting on myrtle rust, July 2011) I had anticipated that it would probably arrive at my place, blown by spring winds, when the weather warmed up. So I was saddened but not surprised to find it infesting two little malletwoods on the eastern side (the upwind side) of our block. Only last week I posted new photos of them, in blooming good health. This week, hundreds of leaves were heavily infected!
A third plant in a somewhat more sheltered spot to the west of the block is (as yet) clean.
I rang Biosecurity Queensland and reported it. (They still want us to report new sightings at 13 25 23). Then I looked at the website which advises us on what to do with infected plants.
The site offers householders a choice of options ranging from taking no action at all, through the use of fungicides, to removing healthy plants as a preventative measure.
Because malletowoods are so very prone to myrtle rust infection, I decided that the plants should go, but cutting them out this morning has made me feel quite miserable!
I don’t plan to remove all infected species in the future, but in the case of these very susceptible plants I felt that attempts to save them by spraying with poisons would probably always be followed rather rapidly by reinfection. I just don’t want a heavily diseased plant in my garden - a continuous source of copious quantities of rust spores putting all my other Myrtaceae at risk (not to mention those of my neighbours, with whom I would rather be on good terms).
I went and contemplated the healthy malletwood, but couldn’t face the thought of removing it today after the emotional stress of cutting out the other two.
I probably should, though.

The Miners’ Canaries
There has been a lot of research done on myrtle rust since it was first found in Australia last year. There is a potential for it to infect almost all of the Australian species of Myrtaceae.
So far, over 100 species have been affected in the wild. There are likely to be many more plants which will suffer to a greater or lesser degree, and growers of Australian natives should become aware which of the plants in our gardens are members of the Myrtaceae family so we know where to look for the disease.
Scientific testing has been established that some species (such as the malletwoods) are very susceptible, some only moderately so, and a few species seem to be immune to it.
If we are looking for it in our gardens, the plants to check most regularly are the most susceptible ones. Some plants known to be badly affected are:
Willow Myrtle Agonis flexuosa (including cultivars “Afterdark”, “Burgundy” “Jedda’s Dream”)
Brown Myrtle Choricarpa leptopetala
Silky Myrtle Decaspermum humile
Beach Cherry Eugenia reinwardtiana
Thready-barked myrtle Gossia inophloia (with popular cultivars like “Blushing Beauty”)
Broad-leafed paperbark Melaleuca quinquenervia (our most familiar paperbark)
Malletwoods Rhodamnia sp. (also called scrub turpentines)
Native Guava Rhodomyrtus psidioides
Aniseed Myrtle Syzygium anisatum (Backhousia anisata)
Rose Apple Syzygium jambos (not native)
Water Gum Tristania neriifolia
Southern penda Xanthostemon oppositifolius
Sadly, these are likely to be plants which may become unpopular in home gardens, because of their higher susceptibility to the ugliness of myrtle rust.

Myrtle Rust Immunity
Early this year I decided not to plant any further Myrtaceae in my garden until more was known about myrtle rust. I had been hoping to hear that some of our locals might be found to be immune to it
The bad news is that the more it spreads, the more species are found to be susceptible.
The good(ish) news is that some plants, though they are infected, are not too badly damaged by it. Seedlings cop the worst dose, though, and we still don't know whether it will affect these species' ability to have babies.
The best news is that 11 species have so far been found to be immune. It’s not many, compared with the plants that have succumbed, but it’s better than none!
They include three locals - Brush box, Lophostemon confertus, Swamp Box Lophostemon suaveolens, and Gum-topped box, Eucalyptus moluccana.
Those of us who have been avoiding planting any new Myrtaceae can now go ahead with these species, happy in the knowledge that they are likely to continue in good health.
In the case of the gum-topped box, the koalas will be pleased, too.

Thursday, October 20, 2011

Brown Malletwood

Rhodamnia rubescens

This small tree is flowering all around the district at present.

It’s a particularly pretty plant, flowering profusely from a very early age. (This plant is only three years old.)
In a month’s time it will be covered in small, red bird-attracting fruits.
See Jan 2011 for photos of the plant and berries.

Common Woodruff

Asperula conferta
This is a modest little plant which can be introduced to a garden and let loose to make itself at home. It spreads by rhizomes, popping up stems where it will, yet is not dominant enough to crowd out other flowers. The dense, bright green foliage of tiny shiny leaves and the sparkling little white flowers make an attractive foil for flowers of other colours, filling what traditional gardeners might think of as the “Sweet Alice” niche.

It persists among grasses, so would be good in a native grassland patch. It is also suitable for garden edging, or among rocks or shrubs.

It gets straggly in autumn, when it can be cut back to ground level ready for the next season’s growth. This ability to regrow from the rhizomes also enables it to survive bushfires, popping up, freshly renewed, when the danger is past.
This tough little plant is hardy to frosts and droughts, and grown is full sun or partial shade
While the life span of an individual plant is indefinite because if its spreading habit, it would be desirable to have plants of both sexes so that they can also spread by self-seeding.

Thursday, October 13, 2011

Climate Change on the Eastern Downs

For most of us, the big climate change question has moved past the bickering about whether it is or is not happening, and whether it’s really being caused by humans.
Now, the questions now are to what extent the people of the world (including us) will be able to keep the change itself within reasonable bounds, how those changes that we are unable to prevent will affect us, and how best to cope with those changes we cannot prevent.
There is general recognition that climate change is not something humans will ever be able to prevent completely.However, the that we can and should do something to reduce the speed and extent of the change is becoming more widespread. An increasing number of individuals are making the choice to live “greener”. Investment in “green” technologies is now widespread, and increasing. Insurance companies are deciding that gambling on "no change" is likely to cause them financial pain, and local governments in coastal areas are planning strategies for coping with sea level rise. The most recent evidence of the changing weight of opinion is shown by our federal government’s recent decision to pass the carbon bills, a move that would have seemed unthinkable only a few years ago.

I recently got hold of the Queensland Government’s 2010 document on the subject, and found it interesting to read their projections (based on climate modelling done by the CSIRO) on how climate change is predicted to affect our own district.
In a nutshell, The Darling Downs will be hotter and dryer.
Calculations (based on the notion that the world will succeed in controlling its greenhouse gas emissions, to some degree), show that on the Eastern Darling Downs, average temperature is likely to be 1°C higher by 2030, average rainfall down by three per cent, and evaporation up by 3-4%. Of course these rather conservative figures will all be exceeded if there is no change (or less change than these researchers hope for), to the current rate of increase in greenhouse gases.
Whatever happens, we can expect fewer frosts, dryer winters, more heat waves and higher evaporation levels.
Water restrictions will be imposed more frequently. Those water conservation techniques that we learned, so that we could go on gardening during our recent 20-year drought, will be needed more than ever.
We’ll need to focus more on choosing heat and drought-hardy species for our gardens. We will enjoy our gardens more if we give up trying to nurse along those plants that would die if we failed to give then regular watering. As a trade-off, we may be able to grow some plants from northern districts which have previously been hard to keep alive through winter.
Australian native plants have had a long history of coping with climatic extremes, so are suitable plants to choose for a garden which will survive through change.
We are likely to show more interest in shady but drought-hardy trees such as our local dry rainforest species, rather than Eucalypts. (We love them, but they don’t keep the heat out of the garden.)
Scrub Wilga Geijera salicifolia( a dry rainforest species) and an Ironbark, Eucalyptus sp. both growing well despite the complete lack of garden care, both equally drought hardy. The wilga wins, in terms of providing livable shade!
Natural regeneration of native plants is likely to result in a slow move of our local species’ ranges, from north to south, and from west to east. Birds and other wildlife will change with the vegetation. Those native plants (some of them already very rare) which survive because they grow on cooler mountaintops may find themselves pushed uphill to extinction. Our conservation attempts should focus on these species.
Weeds which are currently kept in check by our frosts may invade. The effect will probably be greatest with woody plants and grasses. Highly flammable species like green panic, which loves to grow on rainforest edges, will increasingly threaten ecosystems that have previously been able to avoid being burnt because their plants have some ability to resist catching fire. (Once set alight, however, these plants are killed.)
Fires are likely to increase, putting pressure on those ecosystems such as rainforests and scrubs whose plants die when burned, and allowing them to be replaced by fire-tolerant species such as grasses and Eucalypts. Meanwhile, householders are likely to want to replace very flammable species (especially Eucalypts and introduced conifers) with non-deciduous plants that have green canopies and a reputation for not catching fire easily. Burning off, a practice which reduces short-term fire risk, but promotes an ecology dominated by flammable trees and grasses, is likely to come under review.
Plant diseases are also likely to spread southwards. So will diseases which affect humans, especially those borne by mosquitos. We may need to become much more careful, as tropical gardeners are now, not to risk our own health (as well as that of, for example, our neighbour’s children), by being careless about having water in the garden.
Our creeks and rivers will run dry more often, with a decline in both water quality and the native species that depend on them. The country is already addressing this problem by reducing rights to harvest water for agriculture. The decisions as to who has a right to how much water is fraught with difficulty, but I do hope that the needs of native plants and animals will continue to be factored in, and balanced with the very reasonable desire by landholders to make a living from their land.
Groundwater supplies will not be replenished at the current rate. We may see more use of soil surface treatments (such as mulch) designed to allow water to soak into the ground rather than run off. Driveways and other outdoor paving might also be used for water harvesting.
We can expect to see more restrictions placed on the use of underground water, as the levels drop ever more rapidly. It’s not wise to spend money on a bore in the belief that it will continue to be possible to fill gardens with plants from wetter climates, and keep them green with unlimited free sprinkling.
We will see more intense storms, rainfall events, and hail. We shouldn’t be lulled, by calculations of dubious mathematical integrity, into believing that last year’s “inland tsunami” was a “once in a hundred year event”, (or some such flaky figure). Our homes and gardens need to be designed to cope with such destructive summer downpours as the one in 2010. (So does all our public infrastructure, but that’s another story.) On the plus side, it is well worth putting in effective roof gutters and extra tanks to harvest these summer windfalls and save them for the increasingly dry winters.
Crows Ash Trees Flindersia australis. This Toowoomba residence takes advantage of a cool site among old trees.Built for Australia's variable climate, this is a dry rainforest species which is likely to weather climate change gracefully.

Friday, October 7, 2011

Hedge Saltbush

Rhagodia spinescens
We caught this cockatoo, the other day, picking pieces off our saltbushes, and flying away to comfortable perch to nibble at the leaves.
Saltbushes are some of the very best plants for a wildlife garden. Their leaves are so very edible by all kinds of animals, (even by humans), and the fruits are popular with small birds.
Hedge saltbush make a very dense ground cover to about 50cm high, if grown in full sun. It excludes weeds very effectively, as well as providing shelter for small creatures.

This saltbush species tends to spread, as the branches lie down and take root, a process which makes them useful for retaining banks.

In this case where they’re being allowed to creep up the slope. New plants are easy to make, and some blanket planting would have the bank covered in a shorter time.
As its name suggests, it also makes a good hedge, with a once-a year trim (in late autumn) needed to keep it to the desired width.

The blue-grey leaves are attractive year-round, but the plant is particularly pretty from February to autumn, when it is in fruit.

When used in landscaping, this plant sometimes pruned a little more than is really necessary and the pretty, bird-attracting fruits never appear! For a good show of fruits, it should be pruned once a year only, in early winter.
Notice the shape of the leaves. In southern forms of the plant the leaves tend to be hastate or triangular. Our local form, with its grey-green oval leaves is a good contrast plant where other saltbushes such as Einadia hastata or Rhagodia parabolica are grown.
See Feb 2010 for more on this versatile plant.

Monday, October 3, 2011

Mountain Burr Daisy

Calotis cuneata

The season is having a hard time getting out of its winter jacket this year - but we know it’s really spring when the daisies start coming out again.
After a slow start, the flowers are beginning to be seen in our local greasslands again.
We have tended to ignore our local daisies for garden use, yet there are a number of suitable species - modest little plants with considerable charm. Several of them, The Calotis species, area mixed blessing because each seedhead matures into a little prickly ball of seeds, which can break apart on contact, and leave seeds sticking in your socks.

The one pictured here is called "mountain" daisy, but this seems to be a bit of a misnomer, as it grows on the gently sloping blacksoil hillsides west of Toowoomba.
This is really only likely to be a nuisance to those who tramp through patches of them, though. The prickles are really neither very sharp or particularly annoying.
Meanwhile, the fresh white daisies are plentifully produced over a long season, and could be a worthwhile addition to a garden. They grow easily from seed, and also spread (though not too vigorously) by underground stolons. They would be happy to be left to creep around in a mulched area of garden.

They are short-lived perennials, best replaced from seed every three or four years. They are quite likely to do this without any help from us, coming up as self-sown seedlings where conditions are right for them.
As with all our local daisies, they are very hardy to frost and drought, and will grow in full sunlight or dappled shade.