Euphorbia glauca, waiu-atua, shore spurge or sand milkweed is endemic to New Zealand and the Chatham Islands, and is found on coastal cliffs, banks and talus slopes, sand dunes and rocky lake shore scarps. It is a perennial herb with multiple erect stems up to 1m tall and underground rhizomes. It has alternate, blue-green leaves on reddish stems that have a sticky, milky sap that can give a burning sensation if it got on your skin. It has flowers that are produced from October to February are in terminal bunches, with each flower surrounded by a deep red cup-like structure with purple glands, and  then fruit occurs from December to May. It is a nationally threatened plant, and  the natural population is declining due to threats from domestic and feral cattle, sheep, pigs and possums, mainly through browsing and trampling, competition from taller vegetation is significant at many sites, and coastal development (e.g., road widening) and erosion are further common threats to most populations. Population fragmentation makes the remnants vulnerable to sudden decline. Some populations on the West Coast of the South Island appear to have succumbed to a fungal disease. Local populations on Banks Peninsula were believed to have been extinct but a small population was found in February 2012 by Ranger Alan McDonald at the Birdlings Flat end of Kaitorete Spit. It is unsure if this was still present local stock, or that it had escaped cultivation from a local garden although there were no cultivated plants found in the vicinity. Local plants around Christchurch have been re-introduced. It is a great plant for coastal gardens and drier sites, and can make and excellent addition to any garden, although it has a creeping rhizome, and you don’t want it spreading too far it may be best contained in a pot.