Eucalypts are Australia's best known trees. There are about 800 species, subspecies and varieties. They are adapted to alpine, tropical, coastal, desert, saline and many other natural land systems. The species occur mostly in extensive forests and woodlands, although in the arid centre of the continent they are largely confined to seasonal stream lines or hills and mountains. Their great variety has provided a wide choice of species for timber, fire-wood, wind breaks, soil reclamation, ornament and amenity, both in Australia and overseas. Eucalypts are now the most widely planted hardwoods in the world and are the basis of huge timber and fibre industries in many tropical and subtropical countries.
From the time of their discovery to the present day, they have exerted a fascination for a wide range of people from the amateur plant enthusiast to the scientist and the commercial forester. Consequently, for a variety of enterprises and end uses in such a varied group of species that are often superficially similar, it is essential to have an unambiguous syllabus of names and a means of identifying them. To this end, we have compiled in EUCLID, the first comprehensive interactive key to the identity of all the 324 eucalypts naturally occurring in that part of southern Australia defined by New South Wales, Australian Capital Territory, Victoria, Tasmania and south-eastern South Australia.
The species of the south-eastern region of the country were taken as the initial EUCLID focus for several reasons. It was esssential to concentrate on those species that were readily accessible in the field so that information and imagery could be obtained relatively easily. This region contains a significant proportion of the commercially important species for which the demand for information is great. In order that the Centre for Plant Biodiversity Research can judge the demand for such products as EUCLID, it was also considered important that the first attempt be distributed in the region with a high potential user market.
All biology students and plant lovers are aware of the problems
and shortcomings in applying traditional keys to the identification
of plants. In EUCLID we use a new and friendlier system for the
identification of eucalypts. Our interactive key is based on 117
characters (morphological, distributional, etc.) which are divided
into two (e.g. presence/absence) to many states (e.g. rough bark
types). The user chooses the characters that are available. Absent
or ambiguous features can be simply by-passed by the user. The great
advantage, therefore, over traditional hardcopy keys, is the freedom
to avoid characters that are unavailable or are difficult to assess.
Being an interactive key, EUCLID is designed for use by anyone,
including those with the most basic knowledge of plants. The users
will be professional botanists, nurserymen, students, farmers, gardeners,
etc., in fact, anyone who simply wants to know the name of a eucalypt
and is interested in the extra information that is presented.
The identification process begins in the conventional word format where options are provided. Features of the species covering the natural distribution (if the provenance of the specimen is known), habit, bark, flower buds, fruits, seeds, juvenile leaves and cultivated seedlings have been coded. These data provide the key characters that may be chosen in any order by the user.
The traditional word key is supplemented by character illustrations which
are "active" and may be selected without recourse to the
word descriptions with which the user may be unfamiliar. Most characters,
therefore, are illustrated by line drawings, colour pictures or
scanning electron micrographs, all of which may be called up on
the screen for confirmation and comparisons. The plant material
used for this imagery is vouchered in the Australian National Herbarium
(CANB). The scanning electron microscopy was carried out on fresh
material (Craig and Beaton, 1996). For final checking, most species
are also illustrated by a collage of colour pictures comprising
the tree in its natural environment, the habit, bark, leaf venation,
buds, flowers, fruits, and a map showing the natural distribution.
EUCLID has a much broader application than identification. The
database includes extra information on common names, nomenclature,
synonymies, an English language description for each species, notes
on related or similar looking species and how they may be distinguished,
selected references to other works on eucalypts and also uses for
the species, e.g. timber, fibre, honey production, shelter or ornamental.
The latter data have been taken largely from the books "Forest
Trees of Australia" (Boland et al., 1984) and "Economic
Plants of Australia" (Lazarides and Hince, 1993).
The morphological and distribution databases are largely derived from the extensive eucalypt collections of the Australian National Herbarium of CSIRO, Canberra, and were supplemented by glasshouse studies for details of comparative juvenile plant morphology and, most importantly, widespread field observations.
The eucalypts, being a large group of great popular and commercial interest worldwide, have been intensively studied and classified for over 200 years. Various authors have proposed that the genus be divided into genera or alternatively into subgenera. Other genera now included in Eucalyptus are Eudesmia, published by Robert Brown in 1814 and Symphyomyrtus by Schauer in 1844. More recently, a new genus Corymbia (bloodwoods and ghost gums) was split from the traditional genus Eucalyptus by Hill and Johnson (1995). Eudesmia and Symphyomyrtus have long been restored to the genus Eucalyptus. We believe also, that while Corymbia may have a scientific basis, separation of this group from Eucalyptus requires more evidence and time for acceptance. Consequently, we have maintained the traditional concept of the genus Eucalyptus for the eight Corymbia species included in EUCLID.
In the recent treatment of the genus Eucalyptus by Hill & Johnson in
which the ghost gums and the bloodwoods were made a separate genus,
Corymbia, the closely related genus Angophora was
retained in its traditional status as a genus. Angophora
has long been considered to vary principally from the genus Eucalyptus
by the nature of the inner petaline whorl of the flower bud. In
Angophora the petals spread in flower while in some closely
related eucalypts, e.g. bloodwoods species, the 'petals' are also
distinctive, but do not open in flower and remain flat and overlapping
in bud as an operculum. We have taken the step of including the
angophoras in EUCLID and refer to all species of Angophora,
Corymbia and Eucalyptus as "eucalypts".