Friday, March 26, 2010

Skeleton fork-fern

Psilotum nudum
The story of the evolution of plants is full of interest and unexpected turns.
Here’s a thing which has often been described as “a plant that evolution forgot”. It so closely resembles the fossils of the world’s first vascular plants that it was thought that it had simply found itself so well able to survive, in its large range of native habitats, that it hadn’t needed to change for some 400 million years.

(Vascular = “with vessels” - the plant equivalent of our own blood vessels. Vessels carry nutriment from one part of the plant to another, and this evolutionary “invention” was the one which allowed land plants start getting height. Up till they evolved, the only plants had been non-vascular ones like algae, mosses and liverworts. The only large non-vascular plants are giant seaweeds. Modern vascular plants, descendants of the skeleton fork-fern’s look-alike ancestor, include ferns, conifers and other trees, grasses, and all the other flowering plants.)

The skeleton fork-fern is not really a fern at all. Like the earliest vascular plants, it is very simple. It has no roots - only some underground stems - no leaves, no flowers, and no seeds - just these strange (and decorative) little yellow spore cases.

As it has no roots, it couldn’t survive without its the mycorrhizal soil fungi, which attach themselves to its underground stems and provide it with the nutrients.
Yet it is a highly successful survivor, growing in warm and cool climates all around the world, and living in habitats from swamps to dry rocky cliffs.
Evolution didn’t forget it, though. Recent molecular evidence has shown that the skeleton fork-fern is actually a highly evolved organism, a descendant of some true ferns. This plant’s ancestors actually had roots and leaves, but has evolved beyond them. It has taken an evolutionary trail which at first glance seems regressive, but you can’t argue with that kind of success!
You will have your own opinion as to whether it is attractive enough to grow it in your garden. I like its much-branched green stems, and its yellow spore cases that look a little like small wattle flowers.
Even if I didn’t, I’d probably want to grow it just because it’s so interesting.

Friday, March 19, 2010

Jewelbox Cassia

Senna coronilloides (Cassia coronilloides)

What a pity it is that in a country as richly endowed as Australia is with Cassias and Sennas, we are more familiar with the foreign cassias that have been brought into the country by the nursery industry. Some of them have gone on to become serious environmental weeds. What a waste, when our own beautiful, easy to grow, hardy native cassias are hardly used in gardens at all.
This one is an example.

It is common in the scrubs on the Darling Downs, and is a very attractive shoulder-high shrub with a long flowering season. It grows happily on a variety of soil types, is hardy to drought and (mild) frosts, and likes full sun or part shade.
The plant on the right is garden-grown, and one year old.
Like all the cassias (native and introduced) it is not long-lived, but good care and annual pruning can prolong its life.
New plants are easily grown from seed.

The plant's common name comes from its richly brown, ripe seedpods, which open along one side like a hinged jewellery box, and display neatly arranged, shiny, black seeds on a soft tan background. Half of them adhere to one side of the pod, while the others (every second seed) are displayed on the other side. If you get the sun on them at the right angle they gleam an iridescent green.
Cassias are outstandingly good butterfly-attracting plants, used by half-a dozen or more of our local species of yellow butterflies which breed on them, and come to the flowers for nectar.

Friday, March 12, 2010

Slender Bamboo Grass

Austrostipa verticillata
This is such a pretty grass, and is flowering beautifully in many sites on both red and black soil on the eastern Darling Downs at present.
It is the smallest of the three local bamboo grasses, rarely reaching waist-height. Its large, delicate-looking pink-green flowerheads make a beautiful show in November.
It is an adaptable plant which will grow on light soils and clay, and is hardy to frost and drought, and grows in full sun or dappled shade.
All the Austrostipa species are clumping grasses which make good wildlife habitat. Because of their beauty, they are all used by professional landscape gardeners.
They make very good wildlife habitat, and their seeds are appreciated by birds and insects.
Once established, patches become self-maintaining. The seeds are “self-planting” having awns (the little whiskers on their ends) which twist more or less according to the humidity, and, with a little help from the wind, make the seeds burrow into the ground.
They are unlikely ever to be weedy, as they are shallow-rooted, easy to uproot by hand. They are also easily killed by lawnmowing, so are easy to confine to their designated garden plot.

Walking-stick Palm

Linospadix monostachyos

The fruits of these pretty little rainforest understorey palms were just starting to colour up when I visited Goomburra a few weeks ago. They are said to be edible, (but why would you?)

They have developed from these odd little flowers, with their strange, crisp calyces.

This is our smallest local palm-tree, typical of rainforest understorey in northern New South Wales and Queensland. It can get to 3m high, but the trunks remain consistently at about 3cm.
Its populations have re-established themselves in our rainforest remnants (which are about a tenth of their original size), after heavy harvesting for walking-sticks in the nineteenth century. These were exported world-wide, so your antique walking-stick, which has come down in your family from your British or European great grandparents, could well be this species. They were made from the whole palm which was dug up and had the roots removed, its swollen base becoming the knobby handle.
This is a plant which should be used far more in our local redsoil gardens, specially by those who would like more local character to offset the “off-the-peg” look of our mainstream gardening style.
It tolerates full sun, but prefers half shade. It is quite drought hardy, but won’t take frost. Frost-free conditions are usually found close to houses and between buildings, which is a good situation for this little palm, with its inoffensive root system.
It does prefer acid soil, though, so if builders have damaged our redsoil’s natural pH by leaving buried mortar and concrete bits lying around, it will need some affirmative action in the form of compost, mulch, and water.
Unfortunately, the seeds can take six months to germinate, which may be why it is not as easy as it should be to buy in nurseries. Small plants grow rather slowly at first - so it is the sort of plant that would only be chosen by people who think their garden has a long-term future. Tuck them in among the short-lived pretties, as part of your plan for long-term succession.
It doesn’t like transplanting, so no-one should be trying to collect wild plants in the hope of giving them a head start.

Friday, March 5, 2010


but not as we know it.
Auranticarpa rhombifolia
(Pittosporum rhombifolium)
It took me a moment to realise what this plant was, when I saw it at Irongate last weekend. Compared with the hollywoods we see in so many local gardens - many of which would be grown from local seed gathered along the range - its leaves are just a bit thinner, less stiff and a bit less shiny. The veins are more prominent on the upper side, and the leaves are much droopier. Each difference is trivial, but the overall effect is of a slightly different plant.
There is a lot of genetic variation within species of Australian plants. One of the good reasons for growing them from local seed - truly “indigenous” plants - is that they may be better suited to local conditions. I imagine that seed from this plant would be hardier to frost and drought, and more suitable for the sometimes very tough growing conditions on the Darling Downs. This was also a broader plant than the more familiar variety, and would make a really nice shady little tree, suitable for a suburban garden on the black soil on the western side of Toowoomba.
This specimen is flowering beautifully. I think of the species as spring-flowering, and around Toowoomba the hollywoods are starting to show their beautiful orange autumn berries already. (They’re going to be magnificent again this year.) So it surprised me to find this one flowering in late February. Perhaps all the hollywoods, even the garden varieties, have been late to flower out there, in those places which have largely missed out on out summer rainfall? Or perhaps this dry scrub version of the plant is also genetically better at opportunistic flowering. This kind of opportunism, where plants can put out flowers in response to rain rather than to the time of year, is a drought survival technique which we could actually expect to be better developed in plants that are adapted to life in dryer climate zones.
Pittosporum species (and this close relative) have the reputation of being some of the best natives for flower fragrance, and if you’re still reeling from the shock of the “perfume” of Parsonsia eucalyptophylla, try this one. It really is lovely.
(See my blogs, April 2008 and March 2009 for more on this species.)


Marsdenia viridiflora
I have been prowling around Irongate reserve again, and this week the doubah are in fruit. Don’t the seed follicles have a lovely peachy blush, where the sun hits them?
They have the obvious Marsdenia-style seam down one side, which shows you where they’re going to split when they’re ripe. This will release a mass of seeds, to float away in the wind on their silky “parachutes”.
These fruits are also sometimes called native pears, they are said to be edible if picked at this green stage, and roasted - apparently a gourmet treat, with a flavour like zucchini.
Those of you who don’t think “zucchini” and “gourmet treat” should fit into the same sentence may find this a surprising statement. I like them, myself, and would be curious to try doubah, but unfortunately I’m bound by my ethical principle that it is environmentally irresponsible to eat bush tucker from the wild.
(When Australians lived on bush tucker alone there were far fewer than a million of them. Nowadays we have a population of over 20 million, and less than 10% of our original bush. The seeds of our local native plants are needed for food by our beleaguered native fauna, and for reproduction by the plants themselves.)
Actually, I’m also a little doubtful about putting doubah into my mouth. This plant, like most Marsdenia species, produces copious amounts of white sap, and my native caution tells me that if not properly cooked - or perhaps if picked too late in the season - it might do me harm.
The name “viridiflora” tells us that its little flowers are bright green
Doubah plants are common at Irongate, and very hardy things. Below the ground they have 10cm potato-like tubers (one per plant) to which they can retreat in case of fire, heavy frost or searing drought. These tubers are also edible, but are apparently watery with an insipid, sweetish taste - certainly not worth killing a plant for!
Doubah are pretty plants, and would be suitable for growing as garden ornamentals - or perhaps in the vege garden, as a bushfood.