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Sunday, 9 October 2016

Points of view on points

A few years back, we were on a rapid chase of rocks, plants and animals in central Australia, and I never noticed one day when I brushed against a spinifex (Triodia) clump. I got back to the motel, washed my socks, and in the dry Alice Springs heat, they were ready to wear at dawn.

Something was wrong, though. My leg itched, and suspecting an insect, I looked closely. I found several seeds which had evaded vigorous washing, and I remembered what Ernest Giles said.

In 1872, in Australia Twice Traversed, he wrote of "…the so-called spinifex or porcupine grass — botanically, the Triodia, or Festuca irritans…"

About a week later, he added "Whenever one moves, these spines enter the clothes in all directions, making it quite a torture to walk about among them." Well, I can confirm that.
Three weeks later, Giles "… fell into a hideous bunch of this horrid stuff, and got pricked from head to foot; the spiny points breaking off in my clothes and flesh caused me great annoyance and pain for many days after." I didn't try that.

A few days later, he that he and the horses were suffering after going through 200 miles of "the vile stuff", and my third shot, showing a Triodia-covered hillside will give you the idea of what it was like.
A hillside covered with Triodia tussocks near Standley Chasm.

Giles usually travelled with a small dog, and learned to carry a dog called Monkey, when they passed through Triodia. That was less possible with camels, and he reported in 1875 that they lost all the hair on their legs up to three feet, and the bare skin turned black. In 1897, David Carnegie's horses and camels were so hungry, they ate spinifex.

Spines and prickles have always interested me, and if you look at, you will find that the Bathurst burr and cobbler's pegs were once a part of my long list of temporary obsessions.

Here are some views of cobbler's pegs seeds, Bidens sp. The first is of a germinating seed, the others are views of ungerminated seeds, showing the prickles that help the seeds attach to animal fur or human clothes.

Why did I have a germinating seed? Parents, grandparents and teachers please note: cobbler's pegs seeds are great for germination experiments (so are dandelion seeds). Hint: a eucalyptus-scented tissue delays germination by several days. I will say more about that, some other time.

Now here, on the right, is a tick, also seen under the microscope: note the barbs on the stylet between the palps! This particular tick was in my neck for several hours, some years ago, and my wife pulled it out with tweezers.  It hurt, so I took a closer look, and realised why so many expletives flew as she pulled it out. Usually, this is the time when some of the tick's gut contents are pumped into the patient.

This pumping effect is why using tweezers is NOT recommended any more. Freeze, don't squeeze!

Lizards have spines, too, and every point tells an evolutionary tale.

Finally, how do you handle an echidna?

Answer: very carefully!  If you do ever need to handle one (I once stopped traffic on the Hume Highway to move one off the road, so this sort of situation can arise*), either use heavy leather gardening gloves, or an old coat, or several layers of thick towelling. At a pinch, two wallets will save your hands...

We cannot call any of these organisms, or their outer layers, pointless.

* I have to say that the Hume Highway drivers I briefly inconvenienced were all considerate and understanding.

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