Recognising the Eucalypt

Written for a school assignment.

Essay | Assignment

Should you ever come to Australia, the most common kind of tree you will find will be the Eucalypt.

You might be able to recognise them by shape: They aren't very tall — most varieties average 10 to 20 metres — but that's primarily due to the poor soil quality in urban areas. They aren't very straight either; their trunks are crooked and will split off early. Neither do they have very full canopies; their crowns appear patchy, with gaps between clumps of leaves.

But there are other trees with crooked trunks, other trees that are short, and other trees with mottled canopies, so more likely than by any of these characteristics, you'll recognise a Eucalypt by its bark, leaves, or fruit — all of which appear rather distinct.

Start with the bark: A Eucalypt grows a new layer of bark every year. This layer grows under the surface, and ends up pushing off the old bark, which ends up scattered across the ground in pieces. However, different species of Eucalypt shed bark differently: Some have bark that peels down in long sections. Others have bark with tessellated patterns, which comes off in chunks. Some have long, string-like fibres, which crumble apart to the touch — these ones are known as stringybarks.

Certain varieties of Eucalypt, however, don't shed their old bark; layers instead pile up over the top of each other. The dryness of these dead layers causes them to crack, leaving large fissures down the tree which bleed kino, a kind of red sap. These trees end up resembling iron slag — which is what earns them the name of Ironbark.

SCAR TREES

Various groups of Aboriginal people would occasionally carve out pieces of bark from Eucalypts — for use in canoes, containers, or shields. As the trees regrew from these carvings, they ended up with round, bulging scars, which is why these trees get called scar trees. After colonisation, most scar trees got cut down, meaning that very few remain today.

Alternatively, you can look at a tree's leaves: Eucalypt leaves don't tend to be as green as those of other trees — often more mixed with shades of grey or faint blue — and they all have a waxy texture to them. The leaves themselves are long and pointed — like spear tips — but they often aren't straight; they bend to one side, and end up pointing downward like a willow's. This is one of the factors that contributes to the patchy appearance of Eucalypt canopies. Almost all varieties of Eucalypts are evergreen, so instead of shedding their leaves seasonally, they scatter about dry leaves all year.

EUCALYPTUS OIL

Like the leaves of all trees in the Myrtaceae family, Eucalypt leaves are covered in glands which secrete oil, which is what gives them their waxy texture. Eucalyptus oil has historically been used for its medicinal properties — both by Aboriginal peoples and European colonists. The oil also ends up making Eucalypt forests especially flammable.

But the most distinguishing feature of the Eucalypt is their flowers: they grow in bunches — like berries — and they barely look like flowers. The petals and leaves are fused together into a small cap known as an operculum. Out of that cap sticks the flower's stamens — long, straight, colourful hairs which are each tipped with pollen. The whole thing together ends up looking like a little broom. After the flower is pollinated, it begins to turn into a fruit — but like the flowers, Eucalypt fruit barely resemble fruit. The inside of the operculum falls out, and the rest hardens into a woody, bell-shaped container, which holds the Eucalypt's seeds inside. These fruit look a little bit like nuts — which is why they are often called gum nuts.

If you ever come to Australia, be on the lookout for Eucalypts — though as has been mentioned, they aren't hard to spot.