A Rare plant in Victoria that is common elsewhere

Crinum flaccidum is lily of floodplains of the Murray-Darling Basin.  It has fleshy, strap-like leaves and large white flowers - the largest of all Victorian Plants.  It is known in Victoria from only seven locations near the Murray River in the far north-west.  All sites, whether within conservation reserves or not, are highly disturbed and support populations of non-native species that constitute more than a third of the local flora. 

The Victorian classification of vulnerable is a fairly obvious one given the above data, but Crinum is not classified as rare or threatened anywhere else because it is one of the most widespread plant species in the country.  Crinum is found in floodplain country in South Australia, New South Wales, Queensland, Western Australia and the Northern Territory and its broad geographic range covers more than 50% of the area of these states.  Therefore it is not considered to be under threat in Australia.

This, of course, raises the question of whether it is appropriate to classify a species as vulnerable in a state which supports about 1% of its total population.  It seems as if this is a pedantic application of a set of rules according to an artificial demarcation line (a state border) that are of no relevance to the conservation of the species as a whole. The truth, however, is that whether or not state borders are natural, there can be no doubt that they represent real ecological boundaries in the modern world. Land management, and hence flora and fauna conservation, is almost entirely controlled by the state governments, and if there are differences in conservation policies or resources between states then it is sensible that each state look after its own as best it can.

The morphology of Crinum flaccidum varies considerably across its range from northern Queensland to arid, inland South Australia.  The flower colour, shape and structure differs from place to place as does the overall size of the plant.  As a consequence the many forms have been assigned different names in past (at least 10 names are used in currently available literature) and, despite the current conservative taxonomy, it is possible (perhaps likely) that at sometime in the future the single species will be segregated into several species or subspecies.  Indeed it is unusual for any species which is so widespread and variable to remain under a single name.  If this happens and the Victorian form - which has been described as being distinct from those farther north - is found to belong to a species or subspecies with a more restricted distribution, then its conservation status would change.

This is, of course, surmise as Crinum flaccidum is still classified as a single species.  Such a situation is not, however, without precedent. Until recently, the small coastal tree Eucalyptus diversifolia was regarded as vulnerable in Victoria as it was known from only a few sites in the far south-west of the state.  Otherwise E. diversifolia is one of the the most widespread and abundant eucalypts in near-coastal South Australia making this situation analogous with that of Crinum flaccidum.  A review of the taxonomy of E. diversifolia (in 2006) revealed that there are three distinct subspecies and the one of them (subsp. megacarpa) is almost entirely confined to Victoria.  A second subspecies (subsp. hesparia) is known only from a small area near the WA-SA border.

This kind of research goes some way towards vindicating the approach of viewing rarity within a state rather than across the country as a whole.