A Native New Zealand 'Punga' Tree Fern with clear spring sky in the background. Punga (Ponga) is the Maori word for Tree Fern. The Punga is also more commonly known as a Silver Fern (Cyathea dealbata). The Silver Fern gets its name from the leaves, as the underside of the leaves turn a silvery-white color with age. It has become New Zealand's emblem in sport.