Drought tolerance and avoidance in the localised endemic Leptospermum grandiflorum and co-occurring species

A physiological case study of the genus Leptospermurn is used to highlight the importance of the historical effects of the dry Last Glacial (30 000-15 000 BP) on current plant distributions in Tasmania. The water relations of the endemic L. grandiforurn Lodd., which has a restricted distribution, is contrasted with three widespread taxa of this genus. The results suggest that L. grandifZorurn is better suited for survival in dry areas, to which its distribution is restricted, than the more widespread species. Leptosperrnurn grandtj7orurn is also shown to have a slower growth rate under moist conditions than the widespread taxa, which perhaps explains its apparent lack of dispersal during the moister interglacial. Thus, historical factors are likely to be the cause of the restricted distribution of this localised endemic to small areas of the east coast of Tasmania.