Recently I had the chance to visit South Western QLD, from Miles and Roma to St George. Occurring in the Roma, St George, Moonie area is a local Ipomoea species commonly known as Weir Vine or Native Sweet Potato, or Ipomoea polpha subspecies weirana. It occurs in mulga (Acacia aneura) and poplar box (Eucalyptus populnea) grassy woodlands on red brown loam soils, frequently found along roadsides where disturbance from grading promotes growth from tubers. It is an ornamental vine, large leaves and flowers typical of the genus with a heavy scent.
An old report of it in a letter stated “On the roots it produces a fruit which is like a turnip when cut but which he states is as juicy as a watermelon and which he has seen as large as 15 inches in diameter. The fruit is relished by blacks and whites, by the former especially. He is certain the plant was growing wild when the country was first taken up and says he does not think it bears until it is four years old. The fruit is not good when cooked but is very much relished when eaten as soon as it is dug up”. It has proven to be highly toxic to sheep and also cattle and stock losses have occurred following grazing of fresh growth particularly when other feed is scarce.
There are three subspecies of Ipomoea polpha, in two states, the NT and QLD. I. polpha ssp. latzii (from the NT, this subspecies was an important staple of Anmatyerre people), I. polpha ssp. polpha (from N Qld, around the Lakeland Downs area) and I. polpha ssp. weirana (south western QLD).
Plants were actively growing in some areas but dying off for winter in other areas. It had been a particularly dry and hot summer also so plant numbers were expected to be down.
Overall, this is a unique and exciting bushfood and we can hopefully appreciate selected cultivars or interspecific hybrids in cultivation in the coming years.
R.W.Johnson. 2006. The enigmatic Ipomoea polpha (Convolvulaceae). Austrobaileya, Vol. 7, No. 2. pp. 311-317