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

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