Euphorbia glauca is a succulent, creeping, herbaceous perennial. It is a threatened endemic New Zealand species that is listed as at risk under the Department of Conservation’s Threat Classification System. While there are numerous colonies throughout NZ, they are generally small. It is in decline nationally and is threatened in its normal habitat. Threats include habitat loss, cross-pollination with similar species and stock trampling. It is a coastal plant that colonises open sand dunes, preferring the more stable mid-dune, though can sometimes be found in the fore and rear dunes. It can also be found growing on coastal cliffs and gravel and seepages near the shore.
Euphorbia glauca grows up to 1m tall with many erect stems, and spreads by underground rhizomes forming large patches. The soft, pale greyish-blue leaves are alternately arranged up the reddish stem. The flowers are small, dark red and occur in bunches at the end of each stem. The flowers are produced from October to February, and fruit from December to May. As with other Euphorbias, all parts of the plant exude a milky sap when damaged.
Euphorbia glauca can be found in the mid-dune areas along the coast in association with (but not limited to) Muehlenbeckia astonii, Ozothamnus leptophyllus, Coprosma acerosa, and Poa cita. For more information about sand dune communities, we recommend DOC’s publication Native Plant Communities of the Canterbury Plains.
For additional photos, visit Alan Jolliffe’s horticulture blog here.