Genetic analysis of native and introduced populations of the aquatic weed Sagittaria platyphylla – implications for biological control in Australia and South Africa

•Sagittaria platyphylla, native to southern USA is highly invasive in Australia and South Africa.•We compared population genetic diversity and structure between native and invasive ranges.•Of the three genetic clusters in the USA, all occur in Australia but only one in South Africa.•Identifying genetic clusters will guide the collection and use of potential biocontrol agents.