The invasive nature of the New Zealand Pigmyweed (Australian Swamp Stonecrop) Crassula helmsii makes it a regular feature of these pages: see, for example, Bridge 2005, Techniques for controlling New Zealand Pygmyweed (BW 17: 19) and Charlton 2011, Eradication of New Zealand Pigmyweed from grazing marshes (BW 23: 32–33). This latest reviews a paper in Conservation Evidence by Paul and Lucy Sims, who used the combined technique of herbicide and burial at two ponds on Mile Cross Marsh, Norfolk.