Tetragonia tetragonoides or New Zealand spinach is a low spreading vine that is very hardy and tolerates both frosty and hot conditions.
Its natural habitat is sandy shorelines and can grow in saline conditions, often forming a thick carpet and climbing through other plants and shrubs.
The bright green foliage is triangular in shape, thick and quite tasty to eat when young, though rather bitter as it ages. It is rich in vitamin C and iron and was cultivated by the European settlers to help fight scurvy - being a very usable alternative to spinach.
Pick the young leaves as needed for cooking, which are particularly delicious when stir-fried. Blanching is required to remove low level oxalates, followed by a rinsing in fresh water.
The plants will continue to produce new leaves throughout summer, so use it as a pick-n-go vegetable.