Thursday, November 26, 2009

Now Flowering in Ravensbourne

Here are three plants whose fruits we notice more often than their flowers. A walk along the lower track at Ravensbourne National Park takes them all in.

Blue ginger Alpinea caerulea

There are a lot of buds on the plants beside the track, so they’ll make a pretty show for some time yet.
Though not as showy as the flowers of exotic gingers, they are pretty little things. They will be followed by showy electric-blue fruits around May next year.

(See entry May 2009 for photo of some of the last crop of fruit.)

Palm Lilies Cordyline petiolaris

The long-lasting bright red fruits are more often seen than these more ephemeral flowers. These beauties are right beside the main walking track, this week.

(See post July 7, for more on this plant)

Black Bean Castanospermum australe
This is one of the dominant trees of the dry rainforest in Ravensbourne National Park. The flowers are everywhere this year, so we can expect a great crop of the giant chestnut-coloured seeds about next Easter. The trees can flower while still quite young, with the flowers sprouting from old wood. Gardeners shouldn’t get too enthusiastic about pruning these plants, as they could accidentally remove future crops of flowers.
On older trees, the flowers tend to be hidden within the canopy. Our attention is often drawn to them by the clamour of nectar-eating birds.
Grown in the open, black beans trees typically become well-shaped specimens, with a dense canopy of shiny, dark-green leaves. (See the tree on the right, in this photo).

They are ideal for gardens which have room for a medium-sized tree, and make an excellent background plant for large gardens.
I noticed recently that the nursery in the Ikea shop in Brisbane was selling “magic beans”. These were pots with newly sprouted black bean seeds sitting on the soil surface. Very ornamental! Young trees can be used as indoor plants, in well-lit situations, for a number of years.
Black beans are toxic, but not really a family problem, as their seeds are not a size which an innocent toddler could easily swallow. Aborigines, whose diet tended to be low in carbohydrates that could be had from them, did eat these starchy things after a long process involved crushing and soaking them in many changes of water to remove the poisons. Modern bushfood-experimenters have tried it. Reports of the results vary. Some have made themselves very ill. All agree that the taste is so boring it’s not worth the trouble, especially when flour is cheap in the shops, safe, and tastes much the same.
The trees were rigorously exterminated from our area by the early white settlers, who believed them to be also toxic to cattle. Some also claimed that it was the size of the beans rather than the toxins which were the problem. Cattle, they said, swallowed them whole, then were unable to regurgitate them for cud-chewing. Intestinal blockages were the result.
I accepted the idea that black bean trees and cows don’t mix until told otherwise by a dairy farmer who had lived all his eighty years on the same property. This contained many of them dotted about the paddocks as shade for the stock, and cattle ate the seeds freely, he told me. He had never had any problems.
He had recently begun to discourage them, but only because he’d found a market for the seeds in Japan, where they were being used to develop a medicine to combat AIDS.
The dark streaky black bean timber is beautiful, and the trees are plantation-grown in the US as well as here. This is a great tree to grow on a “boutique” timber plantation.
Typical dry rainforest trees, they are drought hardy, and tolerate light frosts. They are quite fast-growing, which is why they dominate parts of Ravensbourne National Park. This park was logged with bulldozers in the thirties, so much of what we see there is still in the relatively early stages of progression to mature rainforest. Slower-growing trees will come later.

Thursday, November 19, 2009

The Best Butterfly Host

Native Caper
Capparis arborea

If we all had a native caper of some kind - one of the Capparis species - in our gardens, we would never (except for a brief period in winter) be without butterflies.
Five local species of butterfly can only breed on caper trees, which are also called bumble trees, for their large, edible lumpy round fruits.

Two of them are pretty butterflies marked in black and yellow; the Caper White (Belenois java teutonica, previously Anaphaeis java teutonica) and the Caper Gull (Cepora perimale scyllara).
The caper white (right) is one of our most common butterfly species. It is a strong flyer, able to travel hundreds of kilometres. In some years enormous numbers of them fly over and through Queensland, delighting butterfly lovers, and providing food for many thousands of nesting birds.

The other three are rather undistinguished: the Chalk White (Elodina parthia) (at left); the Common Pearl White (Elodina angulipennis); the Narrow-winged pearl white (Elodina padusa). These can be a little difficult to tell at a glance from the feral cabbage white butterfly which is the most common white butterfly seen in our gardens.

In the bush, a concentration of fluttering white butterflies draws our attention to the presence of a caper tree. Having one in a garden would ensure that butterflies were present the whole season long, their fluttering hordes (and the birds they attract) being as much an ornament to the garden as the plant itself.
This native caper is in flower in Franke Scrub at the moment. It’s worth a visit, just to smell the strong, sweet perfume of the flowers. Each flower lasts only a day, but the tree still has hundreds of yet unopened buds so will continue to delight for some weeks.
Look for it on the northern edge of the scrub, close to the road. (You can see it easily from your car). It is a good specimen of this small tree species, showing the typical dense, shady canopy.
Capparis is a prickly genus. Tiny plants are very prickly indeed, with a pair of thorns at the base of each leaf. As adults, they lose the prickly habit to a certain extent, but if you examine the Franke Scrub caper tree you will still find traces of those paired thorns, which help to identify the tree.

There are lots of chrysalises on the Franke Scrub caper tree, and some evidence that caterpillars have been at work. I took this particular chrysalis home to see what would hatch out.

And here is the result.

(For more on native capers, see articles Sep09 and Dec08)
For directions to Franke Scrub, see article, Sep 09

Thursday, November 12, 2009

Bat’s Wing Coral Tree

Erythrina numerosa

Now is the time to get out to Prince Henry Drive, to see this glorious tree in flower. It’s really excelling itself this year.

This is also a great opportunity for birdwatchers to see the smaller honeyeaters which flock to the flowers.

If you’re like me, you’ll want to wear your bushwalking boots and get out three times along the route for a little walk down the slope, to appreciate this beautiful plant to the maximum.

If you're not into stopping and walking, do at least get someone else to drive you, so you have time to look across the hillside and appreciate just how many hundreds of these trees grow in this area. They tend to be inconspicuous until this time of the year, when they drop their leaves and blossom profusely.

The “batwing” leaves vary in shape according to the age of the trees, with those on young trees being particularly ornamental.

These coral trees grow naturally in and on the edges of dry rainforest. Their presence all over these slopes tells us that this environment was once extensive there.
There are few large trees in the area. Normally, we would expect to see them with diameters of up to 80cm, in the gullies and more sheltered places, but no doubt the fires which occasionally ravage the area keep them under control
Bat’s wing coral trees are easy to grow, provided they can be protected from frost in their early years. They also need to be protected from hares, wallabies, cattle, camels, etc, until their edible leaves and twigs reach a safe height.
Not everyone loves them, because of their prickles. The trunks of young plants, bristle with very sharp ones (which they need because so many animals find them tasty). I have found it worthwhile to go over the trunks of the trees in my garden with manicure clippers, to create something a bit more hand-friendly and child-safe.
As the trees age, the bark tends to grow over the prickles, and old trees have smooth trunks. Removing the tips does mean that they disappear all the sooner.

The soft timber was regarded as valuable by aborigines, who used it for coolamons and shields. Coral tree shields were also used as a base, when making fire with the friction method. European settlers used it for floats for fishing nets, polo balls, and brake blocks for horse and bullock-drawn vehicles.
The very hard orange seeds have a long history of use for jewellery.

Our Escarpment’s Vegetation

Before white settlement, the vegetation along the escarpment of the Great Dividing Range in the Toowoomba area would have looked very different.
It would have consisted largely of dry rainforest, with pockets and lines of dense moist rainforest in the gullies and stream beds. Both kinds of rainforest were described by the settlers as “scrub”, a term still often used for the drier types of rainforest vegetation.
There were plenty of permanent waterholes, such as the large one, still being marked on late 19th century maps, below Prince Henry Drive. There are still people who can remember swimming, on hot summers’ days, in the pool at the base of Highfields Falls.
Eucalypt grassland would have been restricted to ridgetops, probably existing in a more or less pure form only on those ridges which were traditional aboriginal travelling routes. Aborigines all over Australia regularly “cleaned up” such routes, by burning. White explorers followed them, because the going was easier, and these ancient travelways have since become our modern roads and highways.
It is worth noting that aboriginal use of fire normally resulted in only small areas being burned at a time. Most of it was done to improve the food-producing ability of the land, where the aim was to create a mosaic pattern of fire recovery areas of different ages. This gave them the maximum variety of foods.
One result was what they called a “clean” landscape, which wouldn’t carry a fire for long distances. Another was that areas of fire-sensitive plants such as rainforest and scrub species were not swept away, as they are nowadays by the runaway bushfires which are the result of post-European fire management - or the lack of it.
The process of wholesale clearing the escarpment’s rainforests and scrubs began in the earliest days of white settlement, when aborigines set extensive fires in attempts to get rid of the first invaders.
Timbergetters arrived with the squatters, felling rainforest trees at first, then turning to the eucalypts. Toowoomba’s early industries - a boiling-down works which produced tallow, and a fellmongery, as well as the steam sawmills which were soon introduced - used much of the “scrap” timber for fuel.
Settlers cleared as much of the “scrub” as they could, because they feared the aborigines who hid in it. They paid particular attention to exterminating small bunya trees, as bunyas were known to “attract” aborigines.
In the late nineteenth century the escarpment near Toowoomba was subdivided into tiny farms, mostly taken up by Irish settlers, who were energetic about clearing the land and keeping it clear, both manually and with fire. The result was the development of the current fire ecology, dominated by eucalypts and wattles, which invaded former rainforest territory. These fast-growing trees created the modern impression that our current fire-prone escarpment vegetation is the natural environment there.
The ease with which privet grows, wherever fire fails to keep the ground clear, tells another story.
Meanwhile the original waterholes and streams have largely dried up. Some of this has been from silting, as clearing exposed the soil. Some resulted from the change in groundwater levels which always results from the clearing of hilltop trees. Drought has an effect, of course, but it has been exacerbated by pumping from bores. Originally the greatest effect came from those used for market gardens, but recently the enormous increase in domestic bores in our suburbs, used largely for watering gardens, has had an effect, with the escarpment streams drying up or being reduced to trickles. This is most easily seen in the huge change to Highfields Falls in recent years. Only 15 years ago I saw a large eel in the pool where now there is only a circle of dry kikuyu grass.
That praiseworthy group, the Friends of the Escarpment Parks, has worked very hard to restore some of our original environment. In this they were supported and aided by the Toowoomba City Council, and perhaps the new council is being as helpful.... There are also private landholders doing wonderful work of a similar kind.
It’s hard to say, though, which is having most effect - the brave efforts at restoration, or the continuing destruction of our original landscape.

Friday, November 6, 2009

Black Jezabel

(Delias nigrina)

He does look painted, doesn’t he? The funny thing is, for a female Jezabel, the glamorous side of this butterfly is not these beautiful undersides to his wings, but the pure white wingtops, which he flashes when he flies.

The grey-topped females find the white very appealing!
With their wings folded, you can’t tell the boys from the girls.
This one, which flew into our garden last week, was looking for a mate.
He would have done better to hang around the bushland, as the girls don’t get too far from the plants where they lay their eggs.
Little caterpillars of every butterfly species can only survive on the correct host plants, and for the glamorous jezabels, mistletoes are it.
They are fairly broad-minded. Any mistletoe from the Loranthaceae family will do.
A good reason for growing one in your garden.

Do Mistletoes Kill Trees?

The definitive answer seems to be a simple “no”.
That they do is certainly a fondly-held belief in some quarters. We have seen it raise its head again with the current debate about the trees lining “Cathedral Drive” at Hampton. One writer to a newspaper has expressed the opinion that the trees might as well be killed, because they’re “infested” with mistletoe.
True, the trees are going to die one day. So am I, but I hope nobody uses this as a reason why I “might as well” be killed at once.
The trees are not going to die from mistletoe infestation, however.
Mistletoes don’t poison trees. Nothing passes from the mistletoe to the tree.
Variable mistletoe Amyema congener.  
This plant is growing on a boonaree (Alectryon diversifolium) in Franke Scrub.

This tolerant mistletoe grows on many different host shrubs and trees, including introduced ones like oleanders and crepe myrtles. Some local native hosts are Auranticarpa rhombifolia, Geijera salicifolia, lillypillies and callistemons.

Mistletoes are only partially parasitic. They make their own food, by photosynthesis, just like any other green plant.
What they take from their hosts is water. The amount they take does exceed what any other little branch on the same tree is taking, as Mistletoe leaves lose slightly more water than the tree’s own leaves - but there’s not much in it. A very small tree carrying a big mistletoe will have its growth rate slowed down, but the effect on a large tree is negligible.
Mistletoes are accused of killing branches, and this is true of some mistletoe species. They hijack the branch, preventing water from travelling past the point of the mistletoe's attachment. Branches killed are usually only very small at the time the "hijack" occurs, and the mistletoe replaces any small gap thus created in the canopy, with its own foliage.

Lucas’s Mistletoe
Amyema lucasii

This is a mistletoe which only grows on Flindersias, such as crows ash and leopard ash. This specimen was also in Franke Scrub.

Mistletoes are relatively short-lived plants. Trees can outlive generations of them. Some of the mistletoe skeletons we see on old dead trees would be of plants which died before the tree did, and only became obvious when the tree itself came to the end of its life, shedding its concealing canopy.
Trees under moisture stress have the ability to restrict their water loss to some extent by restricting the flow to their outer branches. This also kills off any mistletoes which were living there, so a drought-stressed tree actually has the ability to rid itself of some of its passengers.

Russet Mistletoe, Amyema miquellii restricts itself to Eucalypts.
A well-grown plant is 2m tall, so needs a large host tree.

Mistletoe “infestation” meanwhile can be a bit of an illusion. Mistletoes are forest edge plants, so we see a lot of them along roadsides, where humans have created long strips of their natural "edge" habitat. Only a few metres into the surrounding bush, the mistletoe population is always much smaller.
A lone tree, left in a paddock is a special case. Left in isolation after clearing, it becomes a “forest edge” all of its own and attracts the mistletoe birds which replant as they feed. It only takes 20 minutes for a mistletoe berry to pass through their little systems and for the seed to be deposited on a handy branch. The birds tend to spend longer in isolated trees before moving on, so these trees do get more than their fair share of mistletoe seeds.
Meanwhile, these lone trees in paddocks, often the source of the “mistletoes kill trees” myth, are already doing it tough.

Detail: Russet Mistletoe, Amyema miquellii. This highly ornamental mistletoe has red flowers, but its showy red spring leaves are an even more showy feature.

There are two reasons why paddock trees seem to die at a higher than normal rate.
One is that livestock collect under them in the heat of the day, and compact the soil with their hooves. Australia has no native hoofed animals. Livestock create a hard soil, unnaturally low in microorganisms - NOT a healthy environment for the poor trees' roots. In addition, stock crowded under trees add high levels of fertilisers to the soil. This is particularly hard on native trees which are adapted to Australia's relatively infertile soils. Even non-natives, quite unblessed by mistletoes, can be killed by excessive fertilising of the sort that paddock trees are subjected to.
A second reason is that some farmers, when they cleared, left the large trees for stock shelter but have never made any provision for their replacement as the trees die of old age. This happening at an increasing rate now, more than a century after the original clearing was done. No tree will live forever!
While it is possible that sick and dying trees are less able to fight off mistletoes so carry a heavier than natural burden, it’s a bit tough to blame the mistletoes for the death of these mistreated, elderly, paddock trees.
So we should stop blaming the mistletoes, and relax and enjoy them instead. They are beautiful plants in their own right, and deserve to be planted in mature gardens for their ornamental qualities as well as their environmental ones.

Brush Mistletoe, Amylotheca dictyophleba

This one grows on introduced trees as well as a variety of natives. We commonly see it around Toowoomba in winter, where is revealed on the London plane trees as they lose their leaves. It gives these trees no trouble, and provides a good source of fruit for native birds.

At least 41 species of native Australian birds are known to feed on mistletoe fruits. Honeyeaters visit them for their nectar. And a great many small bird species nest in their dense foliage. These are great bird-attracting plants!
There are also some beautiful butterflies which are disappearing from our suburbs because they can only breed on mistletoes. We need more of them!
If you’re worried that a too vigorous mistletoe might damage the tree that is the pride of your garden (though it probably won’t) you can prune it just like any other plant. Reducing its size will give the tree a chance to recover if indeed it was feeling the stress.
(Note: the particular mistletoe species shown here are members of the Loranthaceae family. The majority of Australian  mistletoes belong to this old Gondwanan family, and are characterised by their showy flowers and edible fruits.)

Thursday, November 5, 2009

Grow your own Thatch

Phragmites australis
(Phragmites communis)
This is the plant you need, if you want to thatch your roof with a long-lasting home-grown product.

These plants are growing in the pond at Peacehaven Botanic Park at Highfields.

“Common reed” is a cosmopolitan plant, native to many areas of the world including Australia and Britain, where it is known as “Norfolk Reed”. (The name “australis” is Latin for “southern” - not “Australian” as Australians sometimes believe.)
In Europe, the plant is grown in specially cultivated reed beds, to supply the thatching industry. For good thatch, the whole crop should be cut each year, so that next year’s crop contains no dead reeds. A roof of these reeds can be expected to last for 50 or 60 years.
Thatch roofs have never caught on in Australia, though. Perhaps the bushfire hazard is a little too obvious!
Common reed is used around the world for making all sorts of things, from mats, baskets, and hut walls, to pens and arrow shafts. Its pretty purplish-brown plume-like seed heads are valued by florists.
In Australia, it is a “bush tucker” plant. The fresh root-tips (rhizome-tips, really) are produced in spring, and said to have a delicious flavour, like asparagus. They can be cooked in much the same way.
Not a true reed, this is actually a species of grass, but it grows in water like a reed. Others might suggest that it grows like a weed. It is certainly a very vigorous plant. With its strongly spreading rhizomes, it can easily fill a dam or pond.
It does have very high value as a refuge and nesting site for wildlife, and is grazed by stock. It can prevent erosion, tolerate salinity, grow in water or mud, and thrive in water as acid as pH5.5, or as alkaline as 8.7. Its only demands are full sun and enough water.
It is suitable for use in a planted wetland for purification of greywater, urban run-off, or even sewage waste. (For these purposes, it needs to be harvested annually. Pollutants are removed with the stems, and new growth takes up further pollutants as the plants regrow.)
Cutting below water-level in autumn kills the plant back, a useful technique where control is needed. If vigorous growth is what you want, it should be cut in back spring