The writing diary of a well-mellowed science writer who cares about the public understanding of science and knows the ropes. This blog bounces between my curiosity, the daily realities of professional writing, the joy of pursuing nature, and my recycling of ideas that won't be in some book or other as far as I can see, but still needed sharing. I welcome comments and suggestions! Spam will be blocked and reported. For my books, see http://members.ozemail.com.au/~macinnis/writing/index.htm
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Friday, 18 July 2014
In my spare time, I am a volunteer in the Nursery group at a local sanctuary on North Head. We concentrate on raising plants and restoring damaged bush, and from time to time, I contribute a piece to their newsletter. I don't think they are very accessible there, so I will pop them in here as well.
Johann Wolfgang von
Goethe had a bit of a thing about leaves. He wrote a poem about the leaf of the
Ginkgo, and probably saw the leaf as
a symbol of love. Goethe was many things, and also a curious botanist—some
might say a peculiar botanist. He thought the leaf was the basic unit of the
plant: "from top to bottom a plant is all leaf…".
I thought of this when I
sighted a Lomatia along one of the
tracks a few weeks back. At least, I think it was a Lomatia, but now I have my doubts, because of where it was growing.
I'll need to visit it later in the year to check the flower, but Lomatia is one of those
That started me thinking about distinctive leaves, like Canada's
maple leaf, the serrated leaves of the Banksia
and the gracefully curved leaves of some gums. Again, once seen, never
forgotten, though I'll bet that somewhere out there, some other plant has taken
on a similar design.
Allocasuarina, or she-oak.
That's why botanists,
both before and after Goethe, used flower parts for identification, despite
Goethe's ideas. Still, leaves help in identification, and they are certainly
A leaf is just a plant's
way of catching sunlight, while hopefully not losing too much water. Most
Australian plants have tricks to hang onto their water. She-oak needles are
really branches with the leaves tightly attached, all except for little scales
Every walk brings me "leaves" to admire, but
some are fake leaves like those on Bossiaea
which are really cladodes, flattened stems. The leaves of wattles are often phyllodes,
flattened petioles or leaf stalks, and in each case, the change is designed to
save the plant from losing water.
Another way to avoid losing water is to discourage
animals from eating the leaves. Biting a leaf opens wounds that the plant
"bleeds" from, and what is eaten represents a loss as well.
That explains the
rainforest leaf below, which I saw on the Dorrigo Plateau.
It has remarkably nasty spines to keep larger browsers away,
though as you can see from the picture on the right, below, small animals just dodge around the spines and much away.
One of the things that changes the form of leaves, that shapes them, is what Charles Darwin called the struggle for existence against predators, though another aspect is the fight against other plants to get a place in the sun.
Listen, young Goethe, forget about plants as symbols of
Even the leaves remind us there's a war on out there. Some leaves are even
Unnamed leaf which has been attacked by a leaf miner.