Distribution and Conservation Status of the Giant Sweet Potato, a Rare Aboriginal Food Plant from Central Australia

The Giant Sweet Potato, Ipomoea polpha subsp. /a/^VR.W.Johnson (ConvoKoilaceae), or "Antjulkinah", is a rare plant endemic to central Australia, and features prominently in the mythology of the Traditional Owners of the area, the Y people. The taxon is known from three sub-populations and has a highly restricted geographic distribution. Our study of the distribution, density and population size of Ipomoea polpha subsp. latr^i incorporated traditional ecological knowledge, and led to the identification of an additional extensive sub-population. The distance-transect method was used to calculate estimates of population size and density for the Giant Sweet Potato, and is one of the only published examples of the application of this method to a plant species. We estimate the area of occupancy of the taxon to be at least 26.7 km^, significantly greater than the population estimate reported by a survey in 1987. Our data support listing the species as Vulnerable under lUCN (2008) criterion D2.