Wednesday, May 27, 2015

Shining Grape

Tetrastigma nitens
Family: VITACEAE

This is said to be Australia’s tastiest native grape. It has a pleasant, sweet flavour, so long as it is very ripe before being picked. A little less ripe and it’s nasty.
A member of the grape family, it is a large and particularly beautiful vine, with its shiny leaves and bunches of bird-attracting autumn fruit.
It is suitable for growing on a sturdy trellis, where it quickly makes a dense evergreen screen, or on a large tree.


Its branches droop when they reach the ends of their supports, as shown in the photo above. This makes it a particularly attractive pergola specimen.


The new spring shoots make a delicate tracery of red and pale green. 


The fruits their relationship to our familiar shop-bought grapes, with their one or two large, grape-like seeds per fruit.


Some plants produce large bunches of grapes, and others have small bunches.


The fruits ripen sequentially, providing food for birds over a long period.

Like many grape species, this one is  polygamo-dioecious. This means that some flowers, on every plant, have both male and female parts, and some flowers are just one sex. The semi-female plants have more fruit than the semi-male ones. For those of us who grow our plants from seed, it’s a matter of luck what we get, but it should be possible to reliably produce good fruiting plants with cuttings from a good semi-female parent.
The ancestors of our modern cultivated grapes were probably plants with fruits of very similar quality to like this one. There is potential for developing commercially worthwhile fruit from this grape species, using modern plant-breeding methods.

This is a hardy plant, surviving the worst of our local droughts if it grows in a place where its roots are shaded and well mulched. The plants are frost tender.

Wednesday, May 20, 2015

Native Caper Tree

Capparis arborea

Isn’t this a silly little plant?
It began by growing straight upwards. Then it noticed the seedlings next to it, on the shelf, and turned to grow horizontally towards them.
The reason is that these little caper trees like to borrow a trick from the climbers. When they are young, they use their thorns to scramble up through the surrounding vegetation to gain a bit of height before they start making serious tree-trunk.
Unfortunately for the high hopes of this little fellow, his seedling neighbours are not as tall as he would be himself, if he only stood up straight!
Notice the thorns on the plant aabove (Click on the photo for a closerr look). Not many kinds of plants have two thorns coming from the point where the leaf joins the stem, so this is a feature which can help you identify a prickly plant. Locally, the only plants like this are Capparis, Apophyllum,Carissa and Strychnos species.
(In my original version of this post I omitted Strychnos from this list. I forgot it because it is so very uncommon around Toowoomba. A reader put me straight. Thanks Mick. I would much rather be told about it when I write something inaccurate, as I would really like my blog to be the best guide to local plants that I can produce, with a little help from my friends.)

As it grows, this little caper tree will stop making straight thorns, and start growing little curved ones like kitten claws.

Meanwhile it will replace those cute baby-leaves with larger, adult ones.


In young plants the thorns are left on the stems after the leaves fall, their neat pairs revealing that the stem belongs to a caper tree.
In older plants, the tendency to make thorns is lost, which makes them nicer to live with, of course, but leaves us without a useful identifying feature if we find them in the bush and wonder what they are. The thorns were there to protect them from munching herbivores - originally Diprotodons and the like - as they grew. Older plants don’t need this protective feature.

On growing up, my little plant can be expected to produce masses of fragile white flowers. Their buds begin to open at about 8 o’clock in the evening, releasing their sweet fragrance and attracting pollinating moths. Soon after noon the next day, the petals will fall.

Notice the long, curved white style in the centre of the flower, with a little green sphere on the end. This sphere is the plant’s ovary, and will turn into the fruit.


Here are fallen flowers, with only the scar left to mark the place where the petals were attached.


The little ovary will grow into fruits like this. They are edible when soft and ripe.


 
Meanwhile, the plant would have produced generations of butterflies, as it is the favourite food plant for a number of different species...


...including this one, the Caper White Butterfly, Belenois java. Usually the caterpillars go unnoticed on the tree, but sometimes, when conditions are just right, they strip the trees bare and clouds of these lovely insects migrate for as much as a thousand kilometres in their search for new host plants for the next generation of babies.

We have several local species of native caper, and one other close relative. To find my blogs about them,  use the white search box at top left to find references to the family CAPPARACEAE

Wednesday, May 13, 2015

Dangerous Fruits


Giant Stinging Tree, Dendrocnide excelsa
Family: URTICACEAE
This wonderful tree pulls more than its own weight as a member of a rainforest community.

It is a fast-growing pioneer tree, quickly filling spaces in rainforests caused by falling trees or human interference.
It grows to be one of the most magnificent tall trees in the forest, becoming part of its upper canopy.


The leaves of young trees tend to be held horizontally, and are a particularly pretty part of the rainforest scene.



Their translucent light green colour makes the overhead leaves stand out against the darker leaves of the higher canopy.

At the end of the tree’s life-span its soft timber breaks down rapidly, completing the cycle of growth, death and decay that provides habitat for so many species.

This tree had fell across a path at the Bunya Mountains, and has been cut by the National Park rangers to reveal the wonderful fluting of the trunk. Note the tiny stinging tree seedling in its folds. Like seedlings of many other species around it, it is entering the race to fill the canopy gap left by the old, dead tree. What are its chances?


The luscious fruits of stinging trees are eaten by birds and bats. In theory, people can also eat them, but, as they are likely to have stinging hairs amongst the fruits, the outcome could be deadly and is definitely not worth the risk!

The leaves support leaf-eating insects, which sometimes make lacy skeletons of them. Insects are part of the food chain, becoming food for birds, and other animals. The skeletonised leaves are yet another bit of evidence that the stinging tree is playing its part in a healthy local ecology.

How Bad is the Sting?

Because it loves to fill spaces, giant stinging tree often pops up beside National park trails or roads, and visitors learn to be wary of its giant leaves. I find their sting about equal to that of the ordinary nettle Urtica incisa and not very dangerous. However,  different people react differently, so it is best always to be wary of any nettle, whatever the plant’s size.
It would be possible to confuse this plant with a much more dangerous plant, the Gympie stinger, Dendrocnide moroides. Gympie stinger is not native to our district, but grows a little to the north of it. It  is a shrub or small tree with leaves very like those of the giant stinging tree, and its sting is very strong.
Science (and my own experience) tells us that the old wives’ tale of rubbing a nettle sting of any kind with cunjevoi sap to reduce the sting is completely useless. Hair-removal wax strips are the recommended first aid. Some people claim they get at least a partial cure by applying the sticky section of band-aids or elastoplast, the stickier the better, and ripping it off to pull out the little stinging hairs.

A Valuable Plant.
Aborigines made nets and lines from the fibres of the bark of the roots, but modern people have found no used for the soft timber, and of course none of us like to get stung! As a result giant stinging trees have been somewhat underappreciated.
So I am delighted when I find it for sale in certain specialised nurseries. It sells to people for revegetation projects where its potential to make a very high contribution to their local ecology is appreciated.

For notes on the other members of the Urticaceae family, use the white search box at top left

Thursday, May 7, 2015

A Very Variable Boonaree
Hairy Boonaree
Alectryon pubescens
I found another leaf shape, at the Bunya Mountains last weekend, to add to my collection of different leaf shapes for this highly variable plant.







 

It tends to grow in the same places as the related scrub boonaree, Alectryon diversifolius, and can be mistaken for it. Both are large shrubs or small trees. However, hairy boonaree is distinguished by its larger leaves, and despite the scrub boonaree’s scientific name, P. pubescens is the one which has by far the greatest diversity of leaf size and shape. Its leaves are generally larger than those of A. diversifolius , and most plants have at least some leaves with a lobe or two close to the base of the leaf, a thing which A. diversifolius never has.

Hairy boonaree gets its name from the hairiness of various plant parts, most notably the seed capsules. They always begin as double fruits, but quite often only one of the two develops a seed.



By contrast, the Scrub Boonaree

Alectryon diversifolius
has a rather limited range of leaf shapes...

 
 

 
 ...and its capsules are not hairy.
 



 

Wednesday, May 6, 2015

The Streblus Mystery

Whalebone tree, Streblus pendulinus (Streblus brunonianus)
Family: MORACEAE

Why do some of our local Streblus seedlings have mature-shaped leaves from birth, while others have odd elongated leaves with lobes?
This seedling at the Bunya Mountains shows the whole range, from long thin baby leaves to the adult-shape leaves at the top.

Here is a closer look at the leaves. I didn't put them in order of age. Leaves like the narrow one at the bottom of the photo were produced first. The leaf second from the top is the mature leaf shape.

So far as I can discover, the reason for the difference is not known. I have wondered whether it indicates whether the seedling is a male or female tree, but have never found anyone who has tracked a seedling’s life from juvenile leaves to flowers to find out.

The male flowers (above) are very obviously different from the tiny green female flowers.


Female trees have these little yellow fruits, which are attractive to birds, including chooks.


In the Streblus fruiting season, these chooks run to my friends’ female whalebone tree, as soon as they are let out of their yard each day. They scratch in the litter for newly-fallen fruit, and will jump up to get them off the tree.

Like so many trees of our drier rainforests, whalebones can be tall trees with no low branches, when they grow in forests. They can also thrive in dry, hard country, changing their shape to suit their conditions.

The paddock this tree grows in has probably been supporting cattle for at least a century. The tree hadn’t even managed to form its typical single trunk before the cows started “pruning” it, but it has struggled on to produce this wonderful bird-sheltering plant, with tight growth of branches and leaves.

For more on whalebone trees, see my blog of February 16, 2008,
or type Streblus into the white search box at top left.