When we bought our property in 2008, we inherited a potted white periwinkle. It grew in the pot for years until we finally had to move it and in doing so had to dig the plant out of the ground as the roots had grown through the base of the pot. The plant in the above photo is one of the original plant's babies and has grown without any help apart from Mother Nature.
I've seen periwinkles growing wild in many places including the outskirts of western towns and particularly in old cemeteries where I think they were originally planted on graves because they are so hardy and need little looking after. This species of periwinkle appears to be drought hardy and will tolerate the heat.
While most of the folk remedies made from white or pink periwinkle are still in use in a number of countries today, these plants shouldn't be used as a home remedy because they contain powerful alkaloids that can have serious side effects.
White periwinkle and pink periwinkle (Catharansus roseus), are members of the Apocynaceae (oleander) family and have traditionally been used as a remedy for stings, as an eyewash, and to stop bleeding.
Pink periwinkle contains nearly ninety alkaloids and six of these have proved to be active in the treatment of cancer. Vinblastine, one of the alkaloids found in the plant, is effective for the treatment of Hodgkin's disease and another alkaloid, vincristine, is used in the treatment of childhood leukaemia. Side effects of both these alkaloids include hair loss and nausea.
While there are very useful wild plants in Australia, we do need to be cautious when thinking about using them as remedies, especially when taking them internally. White and pink periwinkles are such plants although it may be acceptable to apply them externally to treat wasp stings.