Ironbark: hard, compacted, furrowed; over whole trunk
Perhaps the easiest bark to recognize
is that of the traditional ironbarks. In these species, the
rough bark becomes hard, compacted and furrowed with age and
varies in colour from grey to black or red-black. Some ironbark
species, however, have all the appearance of the hard, furrowed
ironbark character, yet the bark is actually soft and somewhat
flaky and friable as in some forms of E. fibrosa and
E. placita. Therefore, the ironbark character may refer
more to appearance and expectation rather than to fact! In
some species of unrelated groups (e.g. E.
sieberi, E. aromaphloia,
E. indurata) the rough bark may be thick, hard and
furrowed as in the ironbarks.
Tessellated: red bloodwoods, yellow bloodwoods, ghost gums
The outer dead bark breaks up into small
flakes (tesserae or tessellations). This bark may be loose
or firmly held to the whole trunk and branches. In bloodwoods,
when the outer, most weathered flakes are lost by attrition,
an orange and brown mottling of the newly exposed underbark
is often produced. The texture of the rough bark is somewhat
corky. Among the red bloodwoods,
particularly inland and desert species, the tessellated bark
is not retained over the whole trunk (e.g. E.
chippendalei). The flakes are looser and are most
prominent on the lower trunk while the upper trunk is often
smooth. There is no wholesale shedding of the flakes in these
bloodwoods and the trunk remains permanently and colourfully
mottled. There is a smaller group with tessellated bark (yellow
bloodwoods) in which the outer, unshed bark is always
loose but remains attached covering the whole trunk and branches.
The outermost layers weather to light brown or greyish brown
or shades of faded yellow but are readily lost by attrition
exposing the underlayers which are bright yellow to golden
such that the yellow bloodwood trees in a forest of mixed
species can be easily seen from a distance. While this type
of bark characterizes the yellow bloodwoods, it also occurs
(though often less spectacularly) in the unrelated northern
species E. similis, E. lirata and E. cloeziana.
Another group, (ghost
gums), has a distinctive type of tessellated bark or lacks
rough bark altogether. Some species are completely smooth-barked
(e.g. E. aparrerinja) while others have a basal stocking
of distinctive tessellated rough bark with an abrupt cut-off
line on the trunk (e.g. E. tessellaris).
Even in the smooth-barked species, the tessellated nature
of the bark is often revealed after fire when the newly killed
basal bark breaks up into rough flakes. Box species often
have some tessellated rough bark (e.g. E.
moluccana,and E. hypostomatica).
In the grey box, white box and black box groups, the outer
rough bark is rough, usually firmly held, somewhat fibrous
though compacted, and ultimately breaks up into small tessellations.
When the outermost, that is, the oldest part of the fragments
fall away, unweathered whitish inner bark is exposed giving
a dark, grey and white mottled pattern to the whole trunk.
In large old box trees the rough bark often becomes looser,
shaggy and furrowed, particularly towards the base.
Stringy or fibrous: stringybarks, peppermints, mahoganies
This is a large group of species that
can usually be recognized by the thick, longitudinally-furrowed,
fibrous bark over the whole trunk such that the bark can be
pulled away in long strings, ie. stringybarks (e.g. E.
macrorhyncha) and some other species (e.g. E.
cinerea and E. robusta). The inner layers of
stringy or fibrous bark can usually be seen to be criss-crossed.
In some mallee species belonging to the group, the stems may
be mostly smooth but the characteristic stringy bark can usually
be seen towards the base. The outer rough bark weathers to
greyish but on stripping the rough bark away, the underbark
will usually be found to be a rich reddish colour. Some stringybark
species have the rough bark to the small limbs, but a few
have notably smooth branches (e.g. E. blaxlandii).
In another large group, the peppermints, the bark is rough
over the trunk and often the branches. The rough bark is similar
to that of the stringybarks but is thinner and does not become
coarsely furrowed in the old trees and the criss-cross pattern
of the underbark is often conspicuous. A small group, the
white mahoganies, is notable for the rough fibrous bark being
held more or less in flattish strips, rather than loose criss-cross
fibres, although the character is difficult to categorise
unambiguously. This type of rough bark is seen most conspicuously
in the famous Western Australian endemic, jarrah (E. marginata).
Box: short-fibred, grey, sometimes mottled grey and white or
The boxes are one of the most difficult
groups to summarize. The bark is often tightly held, sometimes
tessellated (see above), but may, in some species, be quite
flaky.Thickness is variable and shedding is irregular or in
many species does not occur at all. The boxes are a large
group of closely related species, but box-type bark also occurs
in other distantly related species (e.g. E.
Imperfectly shed ribbons, strips
The bark on the stems, and possibly the
larger limbs, appears loosely rough, due to the imperfect
shedding of dead bark. The general appearance is quite variable
depending on whether a given species normally sheds in long
coarse ribbons, shorter thin strips or in irregular flakes.
For example E. hypochlamydea often has a rough trunk
clothed in coarse, partly detached ribbons which hide the
living bark; E. praetermissa has its trunk lightly
covered with thin short strips of dead bark; and E. astringens
has a trunk that is often almost smooth but seasonally may
have numerous small rough curling flakes of dead bark adherent
to the surface giving a scruffy appearance.
The “imperfectly shed ribbons, strips
or curls” should not be confused with “loose basal slabs”
which implies a thicker accumulation of dead bark usually
on the lower stem or bole.
A few species (e.g. E. elata) are
rough for the basal 1-3 m only. They may be known as blackbutts.
This originally fibrous bark becomes suffused with exudates
and hardens the bark somewhat similarly to the unrelated ironbarks.
The bark colour is invariably very dark brown to black. In
E. sieberi this type of bark may cover the whole trunk
and be quite fissured or furrowed, while the branches are
Loose basal slabs: apparently rough, particularly the lower bole
All smooth-barked species shed their dead
bark at some time. Many species, particularly in cultivation,
hold some of their dead bark loosely over the bole for some
time before it is shed. Particularly old individuals may also
exhibit this character. This type of "rough" bark is to be
distinguished from distinct, firmly-held rough bark. Clearly,
this is an ambiguous bark type which takes experience to assess.
If no decision can be made, this and another bark form should
be selected, or the rough bark character bypassed altogether.
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