Moonlight cactus - Harrisia martini

also known as Harrisia cactus, Harrisia tortuosa and Harrisia pomanensis. It seems, according to the website I discovered, Harrisia cactus is a native of Argentina and Paraguay, South America. It was introduced to Australia as a pot plant in the 1890s. In 1935 it was first recognised as a serious pest in the Collinsville district and by the 1950s was rapidly spreading south. Really don't know how they landed up in our estate's back garden?

I think they are beautiful, especially the beautiful red fruit. Charmaine and I discovered them today and actually wanted to take a couple of pieces to replant in our garden, but changed our minds rapidly after reading this! :-)