Threats to the survival of the Grampians pincushion lily (Borya mirabillis, Lilliaceae) —a short-range endemic from western Victoria

Abstract

The Grampians pincushion lily (Borya mirabilis Churchill) is a resurrection plant confined to one population at a single rock outcrop in western Victoria. It is a taxonomically well-defined species and geographically widely separated from its most closely related congeners in the south-west of Western Australia. Monitoring over a 12-month period showed a significant decline in population condition that was associated with soil disturbance and damage to associated vegetation. Although able to reproduce vegetatively, B. mirabilis is not known to produce viable seed. Molecular work revealed that all plants in the population were likely to be genetically identical. Investigation of the breeding system showed that pollen viability was low and pollen tube growth was possibly insufficient to fertilise ovules. One explanation for lack of effective sexual reproduction is the presence of a mechanism for self-incompatibility. The decline in population condition and lack of ramet establishment at present are predominantly a result of high levels of ground disturbance from pest animals. Without active and immediate site management the population is likely to become extinct under current circumstances.