Flowers have their seasons, but over the past winter (2020), we have never seen less than 25 species in bloom on any given day, and as this is written in late July, there are 45 species on display, including five wattles. Of course, to spot these, you need to look carefully and walk around quite a bit...
All names are subject to revision, and I am adding bloggish notes at the end.
Above: Acacia longifolia, Sydney Golden Wattle, flowers mid-July into August. The second shot is a photomicrograph. The early regenerators planted a lot of this in recovery areas, because it was quick and easy, but it tends to take over, so now we plant it less often, and prune the ones that are there. Luckily, it's quite good at self-seeding.
Above: Acacia suaveolens, Sweet Wattle, flowers autumn and winter. The second shot is a photomicrograph. During the coronavirus lockdown, this has been one of the more obvious bush flowers.
Above: Actinotus helianthi, Flannel flower, supposedly flowers spring and summer, but we seem to have
a few, all the year around.
Common in the Third Cemetery. There is also a very small species, A. minor, that flowers in winter.
Above: Allocasuarina distyla, sheoak, showing the female flowers, and a Boronia ledifolia which flowers in spring. She-oaks are wind-pollinated, and they look a bit like pines, but they are not pines.
Above: Two examples of the Banksia inflorescence. Note the bee in the second shot. This genus is all over North Head.
Why? Well, the vegetation is called Eastern Suburbs Banksia Scrub!
Above: Two more examples of the Banksia inflorescence. Probably B. marginata and B. aemula, I think.
Above: Two more examples of the Banksia, and these two are defining members of the Eastern Suburbs Banksia Scrub. B. ericifolia and B. serrata.
Above: Conospermum, sometimes called smokebush (a name better justified when applied to the West Australian species). The second shot is a photomicrograph.
Above: Darwinia and Drosera, probably D. spatulata, which is more correct than D. spathulata.
Three good places to see sundews (Drosera):
On the eastern side of Soggy Bottom;
On
the hanging swamp track, on the western side, 30 metres north of where a short steel branch track goes east;
and
When you are on the western perimeter fire trail, just after a steel track comes in
from the east, look at the damp ground on the eastern side.
Above: A photomicrograph of the flowers of Monotoca (broom-heath) is one of the defining members of the Eastern Suburbs Banksia Scrub. The second shot is a photomicrograph of the Grey Spider Flower (next).
Above: Grevillea buxifolia, the Grey Spider Flower, which flowers for much of the year. The second shot is a photomicrograph.
Above: Hakea needlebush in flower, and a fruit which has fully opened after ten days, dropping seeds. After a bushfire, the fruits open even sooner.
Above: Two creepers, Hardenbergia violacea (a pea) with Acacia suaveolens, and the yellow flower is Hibbertia scandens. You will find the Hardenbergia mainly in planted areas.
Above: Isopogon, drumsticks.
Above: Kunzea ambigua or Tick bush, and Kunzea capitata or Bachelor's buttons.
Above: Lambertia, or mountain devil, and Leptospermum laevigatum or ti-tree.
The climax community on North Head is dominated by Leptospermum laevigatum and Kunzea ambigua.
Above: Leucopogon or bearded heath has tiny five-pointed stars for its flowers. The second shot is a photomicrograph.
Above: an unnamed orchid (we have lots, but they are all tiny) and Patersonia glabrata, a native iris. The Patersonia flowers for a single day but does so on a number of days in 'spring', which means around July. The best place to see these is on the Inside track as you approach Soggy Bottom, and on Lookout Hill. They are also common in the Third Cemetery.
Above: Probably Philotheca buxifolia that was Eriostemon when I were a lad (Paul Wilson changed the name), and a Dampiera, one of the Goodeniaceae. There are complicated rules about naming life forms.
Above: Woollsia pungens, a member of the Epacridaceae, and the flower stem of a Xanthorrhoea.
Common species are listed as Banksia aemula, B. ericifolia, B. serrata, Eriostemon australasius ('pink wax flower'), Lepidosperma laterale ("sword-sedge"), Leptospermum laevigatum, Monotoca elliptica and Xanthorrhoea resinifera.
The community is found on nutrient-poor wind-blown (aeolian) sand from dunes blown in during the last Ice Age, across a number of sites, but 47% of all the ESBS that is left in the world is to be found on North Head.
Air humidity, the amount of water vapour in the air, plays an important role during the bushfire season. The risk of bushfires in summer depends on the amount of fuel-wood, twigs and leaves-in an area and the wind strength and direction, as well as air humidity. When the humidity is high, the fuel has more water in it, so any fire will be less intense and it will spread more slowly. When the fire authorities estimate the bushfire danger, they measure fuel moisture and the humidity of the air.
Bushfires are a part of high summer in Australia. In winter each year, Australians carry out control burns, small fires aimed at reducing the amount of standing fuel. These may help to contain the fires or stop them, but given the wrong weather, no amount of control burning can stop fires happening somewhere. The science is against any other outcome.
A note first about terms: in Australian English, 'bush' is what others might call forest, heath or scrub. The term was brought to Australia by early settlers who had previously lived and worked in North America, so this quintessentially Australian term is in fact an early American import! A 'bushfire' is a fire running wild in the bush. Many botanists in the past have been forced to change their research to 'bushfire regeneration' after their plots were burned out, and the cost of fires has meant that there has been a great deal of research on the topic.
First, let us consider the biology of bushfire in Australia. Fire is a natural part of the bush cycle, so the natural environment should survive fairly well, just so long as there is no heavy rain, too soon afterwards. That is why the fire fighters will concentrate on saving property and lives. They will fight fire with fire, knowing that what they burn deliberately will grow back again, refreshed by the flames. Australia's bush, after all, lived with fire for many millions of years, long before humans came here. The bush will grow back after the fires have done their worst.
Next, let us consider the geology and geography of urban Sydney bushfires. When the first Europeans reached Australia in 1788, they settled in what is now Sydney, either on flat land near the sea or on the ridges.
Sydney sits on a bed of sandstone, two to three hundred metres thick, with joints running north-south and east-west. It was laid down in a Triassic delta, rather like Bangladesh today, with a huge river braiding back and forth, washing out the finest minerals, the clay and other mineral-rich sediments, and leaving just the quartz grains behind. The grains were rounded, and had probably been in an earlier sandstone somewhere else, but they settled where Sydney is now, almost 200 million years ago, waiting to play their part in shaping modern Sydney. Some of the sandstone beds are better bonded than the others within this 'Hawkesbury sandstone', but they are otherwise pretty much the same, right through the deposit. (Hawkesbury, in case you are wondering, was a minor 18th century English politician who had a local river named after him. The stone was later named after the river.)
In the last Ice Age, the sea level around Australia was much lower, due to all the water tied up in the northern glaciers. Then, today's Sydney Harbour was a river valley, shaped by the jointing pattern in the sandstone. Joints, planes of weakness in the stone, were eroded into crevices which became valleys, with the more resistant sandstone forming ridges. Later, the sea level rose, creating a 'drowned river valley' with a characteristic fern leaf shape, the modern Sydney Harbour. A few of the higher ridges have a shale capping which offered rather better soil than the sand which derives from sandstone.
The first whites settled on the coast, then headed (a) for the flat land of the ridges, where roads were easier to build, and (b) for the richer soil on the shale-capped ridges. First, they built small farms and market gardens, then roads were built to service these, and soon the residences followed, as a young city grew. Down in the valleys, close to the sea, the bush was left alone. It was too hard to build roads down to there, and so people left it alone. Even today, much of the valley bush is preserved, with homes sitting on the ridges above: a sure recipe for trouble, because heat and flames rise.
Fuel builds up in the bush over a period of years. Gum trees shed their bark, branches and leaves, smaller shrubs in the under-storey die and are replaced by others, and after a few years of recovery, the lowest three metres or so is a closely packed mass of dead and drying twigs. Until they break and fall, these pieces of finely divided wood rot very little in the dry bush, and even on the forest floor, rotting is a slow business, for the sandy soil drains fast after rain. Heath regenerates fast. Some of them can be ready to burn again, just six months after a major fire. Other areas can take ten to twenty years to be ready for a major burn. As a general rule, after 40 or 50 years, any area at all will be ready to sustain a 'blow-up fire'.
Now for the physics of bushfires in Australia. When any fire starts, it begins very slowly. It takes time to develop from a maker of smoke wisps into a maker of misery. The dangerous fire is one that roars and gusts through the tree tops, the crowns of the trees, a firestorm traveling at 50 kilometres an hour or more, leaping ahead of itself, and destroying all in its path.
Crowning fires can cross 400 metres of open water, as the sparks and burning rubbish fly up in the roaring flames, and then tumble down on the other side. Any footage you see on your local TV will be of these crowning wildfires. You will see flames gouting 30 metres or more into the air, searing the upper branches of gum trees, leaping across the fire breaks, and almost impossible to control until the weather improves.
Now let us look at the question of weather and bushfires. The weather is the last factor in the bushfire equation. At the moment, we have hot dry nor-westers, gusting at up to 50 knots, pushing the fires downhill as well as up. Usually, a fire front can be beaten as it crests a ridge. Fires go fast uphill and slow downhill. On the forward side of any advancing fire, you will find a wind blowing towards the flames at the front of the fire. If you can set small fires on the far side of a ridge, they will gather strength and rush up, sucked in by the fire wind from the blaze on the other side, until the small fires meet the major fire coming the other way.
In this style of fire-fighting, the major fire limps over the ridge, only to find that most of the fuel in its path has already been burned. Starved, it falters like a wounded beast, and puny men and women rush in to attack it with sprays and hoses. But with high winds, this ploy is too dangerous to attempt, as the fire lighters in its path could easily be over-run, as it leaps over the fire break they have just made.
Within hours of the fire, the seeds will be dropping from the woody fruits of the she-oaks, Hakeas and Banksias, and the trunks and underground stems of other plants will already be starting to shoot. In three weeks, there will be green all over the bush. In time, the bush will recover, and so will the animals. The homes can be rebuilt, and lives, so long as they have not been lost, will go on. It is all part of the natural cycle. The animals will take longer, but some will survive, and others will move in from unburnt areas, but recovery is a slow natural cycle.
In 1829, The Sydney Gazette and New South Wales Advertiser described "a dilly (a luggage bag which the females carry), this is formed of the leaves of a species of Xanthorhea, strong enough to hold any thing..."
Louisa Meredith outlined some other uses in 1844:
"A resinous gum exudes from the grass-tree, said to resemble in great measure the "dragon's blood" prepared from the Pterocarpus and Calamus. Boiled with oil, it has, I believe, been successfully used for covering the bottom of vessels, instead of pitch. I have also heard that the natives cut out the pith of the trunk to eat."
Interestingly, one of the few reports of Indigenous fire-making involves Xanthorrhoea stems, and it came up in a small piece on what we could now call bushcraft: some of the invaders were learning from the Australians.
"The best mode is this. Cut a piece of the dried stalk of the grass tree in two; point one half, and hollow
out in a cup shape one end of the other half, so that the pointed part may fit as nearly as possible the
hollowed part; put the hollowed piece between the knees and inserting the point of the other, which is held
between the palms of the hands, twirl it rapidly and regularly round by moving the hands backwards and forwards.
If this is dexterously managed the friction will soon produce fire."
—The Sydney Morning Herald, Saturday 13 September 1851, p. 4
Most older works (and even older people) call the sheoak Casuarina, but when Laurie Johnson examined the genus, he split it into two genera. The species that was first named Casuarina and its relatives kept their original name, but the "others" were given the name Allocasuarina, which simply means "other Casuarina". To save squabbles, I'm just calling them sheoaks here, and I hope that everybody will just accept that. Just don't call them "pines"!
When you look at them closely, the 'needles' which should really be called branchlets, look a bit like bamboo, but just as they aren't pines, the sheoaks aren't bamboos either. Bamboos are giant grasses while sheoaks are trees. Some species, like Allocasuarina distyla have male and female flowers on separate plants. Those are female flowers you see up at the top.
Sometimes there are surprises in sheoaks in the bush or in your garden, because some of the fruits look very different.
The sheoak on the right was attacked by a midge, called a gall midge, which laid an egg inside the bud that was going to be a fruit.
The midge takes control of the fruit and turns it into a home. If you find one of these in your garden, you can slice it open (though if you are young, it's a good idea to ask for some help: the fruits are tough and woody, and it's hard to get the grub out, without either slicing it-or you! Use pliers to hold the fruit, and cut away from you.
There is a curious relationship between the number of leaflets around the stem, and the number of seed places around the 'cone', but you'll have to find that out for yourself.
I have a partly-baked notion that one of our problems in cultivating the rare and endangered Eucalyptus camfieldii may stem from not having the right fungi where the trees are growing. So far only about 10% of Australia's native fungi are known to science, yet they are one of the most pervasive and important life forms on the continent. So who knows what else is out there, waiting to be found?
There is a basic rule about naming things: you don't name things after yourself. Bass Strait was named by Flinders and Flinders Island was named by Bass, somebody else named Brown's River in Tasmania, Banks collected the first Banksia but it was baptised by Linnaeus' son, Woollsia pungens was named by Ferdinand von Mueller and Bauera was named by Banks. It's just not done to apply your own name to localities, laws or living things.
The rules set out how a species should be named, how it should be associated with a type specimen, so that others could refer back to the original later on, it specified how the description should be laid out, and how it should be published, so that other scholars in the field could read it. The codes of nomenclature also set out rules for dealing with clashes, and required that a new name should not be used until it had been associated with a specimen.
Biologists have one basic rule for naming: if a name is validly given, and has not been used before, it is to be recognised. When a genus name is changed for valid scientific reasons, the rest of the name remains, so the clam that was once Abra cadabra is now Theora cadabra.
Fossils are typically found in hot dry places. They occur everywhere, but the best exposures are in places that are undeveloped, not covered by concrete or pastures. So people who go looking for fossils often find themselves in places where the local flies regard them as a Heaven-sent source of liquids. That can make the pursuit of fossils a wearing experience, especially when coupled with the heat, the thirst, the hard work and all of the other travails.
On the other hand, being happy humans, bent on discovery, palaeontologists are not given to bouts of depression and misery. They are, however, given to a degree of warped humour which tends to emerge in the names of the fossils. This is why we find fossils with names like Montypythonoides and Thingodonta. At least names like that are unlikely to have been used before.
There is less excuse for other biologists, but if you can get a name like Humbrella hydra ("in honour of Professor Humm") accepted for a parasol-shaped alga, why not? Lou Eldredge named Didemnum ginantonicum after his preferred tipple, and two gentle souls called Miller and Wheeler named five fungus beetles Gelae baen, Gelae belae, Gelae donut, Gelae fish and Gelae rol.
The code of zoological nomenclature, the set of rules that says how specimens may, and may not, be named. For example, the Australian platypus was named Platypus anatinus in 1799, and then later named Ornithorhynchus paradoxus in 1800. Each name was given with a description, but there was a small problem - the name Platypus had already been given to a beetle in 1793.
That meant the name could not later be given to the monotreme from Australia. You can have a plant and an animal with the same genus name, but never two plants or two animals with the same genus name. (This is one reason why names, once coined from Latin or Greek, are now often taken from the language of the area where a new specimen is found, or from an unusual place like tiny Coopernook in Australia, which gave its name to Coopernookia, a member of the Goodeniaceae.)
Under the circumstances, the first legitimate genus name given to Australia's swimming, egg-laying mammal was Ornithorhynchus, but even if the genus had to change, the first legitimate species name given was anatinus, and so the curious and shy mammal is now properly called Ornithorhynchus anatinus.
Australia's other monotreme, which we call the echidna was dubbed Myrmecophaga in 1792. That was the name of a South American placental ant-eater, and would never do for the unrelated Australian monotreme. The French scientist, Georges Cuvier suggested Echidna, the name of a serpent in Greek mythology. Sadly, this name had been given twenty years earlier to a moray eel, and so the animal ended up as Tachyglossus, except to Australians, who had adopted 'echidna' and 'platypus' as common names, and stayed with them.
The page was first created on 29 July 2020, revised 1 August 2020.