Bark
Having taken into account the habit features, the next important character to assess in eucalypts is the type of bark. It pays to think in terms of the growth processes. Each year there is an increment of living bark that results in the continual expanding girth of the tree. In all species the outermost layer dies each year. In about half of the species this dead layer completely sheds, exposing a new layer of living bark, and the process continues year after year. These are known as the smooth barks. The dead bark may be shed from these trees in large slabs, in ribbons, or in small flakes. Invariably the newly exposed living bark is relatively smooth and brightly coloured but this fades with weathering. Often the dead bark comes off in pieces at various times of the year such that the trunk is mottled depending on the amount of time the newly revealed patches of bark are exposed to weathering.
A curious but easily recognised bark type is the minnirichi which is restricted to a few species from southern Western Australia and arid Central Australia. This bark seems rough at first glance and on close inspection is seen to be formed of partly shed longitudinal strips that curl outwards, initially exposing pale or greenish underbark. The older attached strips turn deep red on aging. In one minnirichi species, in