A Rare Plant that was once Common

Pimelea spinescens is a small, compact shrub which grows in lowland grasslands in central and western Victoria.  Virtually every population is small - usually less than 100 individuals - and is almost always within vegetation that has been significantly disturbed.  Most populations are on roadside verges, railway sidings or in paddocks and they are usually associated with substantial numbers of non-native species - typically 25-50% of the plant species in vegetation that supports Pimelea spinescens are naturalised aliens.  More than 98% of the records for this species are from private property or public land that has not been set aside for conservation purposes.

Pimelea spinescens - Spiny Rice Flower : Endangered in Victoria : Found only in Victoria : Critically Endangered in Australia
Pimelea spinescens
© Paul Gullan/Viridans Images 

There are two subspecies, Pimelea spinescens subsp. spinescens and P. s. subsp. pubiflora. Until recently the latter subspecies was considered to be extinct but in 2005 a small population was discovered in western Victoria.  All the plants are on a roadside verge immediately adjacent to a paddock but ironically, the grassland in which it is found is relatively undisturbed - much less than a typical site for the subsp. spinescens - and supports a range of other native species and few non-natives.   Nevertheless, the small size of the population, and the tiny area covered by vegetation in which it grows, means that this subspecies is especially vulnerable to disturbance.

A few years after the population was discovered and examined by scientists from the Victorian Department of Environment, Water, Land and Planning, the vegetation was inadvertently destroyed by workers carrying out road maintenance.  It appears that the significance of the site and the conservation monitoring program did not find its way to the Victorian road authorities.  The future of the subspecies is now unclear.

Lowland grasslands once covered more than a third of the land area in Victoria.  They were the first ecosystems to be significantly utilised for agriculture and sheep were grazing across their full geographic range within decades of European settlement.  Their major components were, unsurprisingly, native grasses such as Kangaroo Grass (Themeda), Wallaby Grasses (Austrodanthonia), Tussock Grasses (Poa) and Spear Grasses (Austrostipa).  But they also comprised a range of herbs and small shrubs, many of which had brightly coloured flowers and led to them be called the wildflower plains in spring and early summer.

As the botanical composition of the grasslands were altered, to provide better feed for sheep and cattle, the native species disappeared and in many cases the first to go were the shrubs like Pimelea.  There is no doubt that the range and abundance of Pimelea spinescens before European settlement was considerably greater than it is today. 

© Paul Gullan, Viridans Biological Databases