Leaf of the Day: Lemon Eucalyptus

I seldom see the overflow car park used at Leu but today the post Christmas crowds were out in force. I think more because it was a free morning and "something to do with the kids", than a sudden great outpouring of interest and affection for the natural world, but it was the perfect morning for a garden walk. Many people are here on holiday from the frozen north and they look in wonder at the citrus trees hanging with fruit, the giant pummelos, the beautiful butterflies, the roses and the just opening camellias.
I went to look specifically at more of the Australian plants and to find out exactly which eucalyptus the beautiful white trunks belonged to. They are Lemon Eucalyptus Eucalyptus citriodora.


3 Lemon Eucalyptus at Leu Gardens

They are beautiful immensely tall trees with all the branches clustered at the crown so no chance of taking a leaf without shinning up 50 ft or more. However there were some old fallen branches and after ferreting around in all the debris at the foot of the trees I found a cluster of the little urn shaped seed pods. They are much much smaller than the big bloodwood pods from last week and of course the leaves from this mature trees are the characteristic elongated shape. When not old and twisted and broken like the ones I have drawn the leaves are a beautiful sickle shape.
The white trunks have bark so snug fitting it looks like tight skin, wrinkled at the joints and there are several strange pock marks above the branch scars. I have no idea what they are.



The lemon scented oil from the leaves is steam distilled and used as an insect repellent although I didn't particularly notice a lack of mosquitoes around the trees. It will have small white spidery flowers in panicles.




Here are a few words about the Lemon Eucalyptus from Stanford University's online "Encyclopedia of Trees, Shrubs and Vines". More here

The tall trunk, with no branches at all up to a substantial height, leaves a detectable record of bygone branches in the form of dimples and pimples on the otherwise smooth trunk. As a branch becomes shaded from sunlight as a result of growth in height, abscissic acid (a plant hormone), causes a brittle zone to form at the trunk. Wind then breaks the branch off cleanly. Research on abscissic acid has received military support aimed at defoliating forests. ( hmmm!)
Gum tree leaves vary a lot in smell when you crush and sniff them because the mix of oils varies from one species to the next, but with the lemon-scented gum the oil is virtually pure citronellal, known as a germicide and mosquito repellent, but with a marvelous aroma for humans. Occasional juvenile leaves can be found near ground level that have a visibly rough undersurface made up of tiny projections containing lemon oil. After you feel the sandpaper-like texture, smell your fingers! Onlookers are astonished by the fragrance; you can put these leaves in your gin and tonic!
(that's better!)

The drawing is of some tatty dried leaves with small bit of twig stuck onto one leaf and some old gumnuts. Sadly these old leaves neither smell of lemon nor are they suitable for my sparkling glass of G & T.

For much more Euclyptus info do visit Gustavo's excellent site Eucalyptologics
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Lemon Eucalyptus and Pods