Depending on which reference you use, there are between 700
and 900 species of Australia’s iconic eucalyptus tree. Something like 75% of
our forests are made up of eucalyptus species, (next is the acacias and then
the melaleucas). Eucalypts grow on tops of mountains, on the coast, in high
rainfall gullies and on dry mallee and mulga plains.
Although considered to be endemic to Australia, naturally
occurring eucalypts are found in New Guinea, Timor and parts of the
Philippines. The genus is cultivated world-wide now, and in some places has
become naturalized.
In 1777, a botanist sailing with Captain James Cook
collected samples from Tasmania’s Bruny Island. In 1788, a French botanist
identified and named the first species, Eucalyptus obliqua, more
commonly known now as Messmate.
Proper identification of eucalypts is not easy at times and
requires a certain amount of botanical knowledge about the bark, the fruit, the
flowers and the leaves. Matters are made more complicated when it is accepted
that some species are known to hybridize. Many factors come into play for the
proper identification of eucalypts:
Geographical
location – elevation or depression, coastal, alpine, etc.
Habit – tall
and straight, small, spreading, single or multi-trunked, etc.
Bark –
colour, form and consistency.
Flower and
fruit – colour, size, shape and arrangement.
Leaf – colour, lustre, size,
shape, arrangement, juvenile/adult and even the arrangement of the veins and
oil glands.
(The glossary for one common text on eucalypts contains
definitions of over 250 botanical terms!)
Many of our eucalypts have learned to deal with fire by
re-sprouting from buds under the bark or from tubers at the base of the tree.
Eucalypts are a valuable and important species for many
reasons. Like all trees, they provide shade, lower the water table, purify the
air and sequester carbon. Eucalypts are notable for their oils, fibre and
timber and of course, many native birds and animals are entirely dependent on eucalypt
habitat.
Not only iconic, but invaluable!