The debate about changing New Zealand’s flag has reignited. (Radio New Zealand’s report: Prime Minister raises prospect of changing the flag.)
The silver fern is one of the favoured symbols for a new flag. Aside from being one of New Zealand’s icons, the silver fern is a real plant. But being on a nation’s flag deserves a background check – what is the silver fern?
- It’s also known as ponga (the Maori name) and Cyathea dealbata or Alsophila tricolor (alternative scientific names).
- It’s a scaly tree fern, with a trunk up to around 10 m tall. There are two principal kinds of tree ferns – scaly and hairy. For more, see Te Papa’s guide to New Zealand’s tree ferns.
- The underside of the fronds is white in most bigger plants. ‘White fern’ would be a more accurate moniker than silver fern. Juveniles start off with a green underside, with the whiteness usually evident by the time the trunk starts to form. The whiteness is poorly developed in many Northland plants, even in adults, which are instead silver or nearly green. Perhaps the silver fern label originated in the north.
- The white or silver colouring extends to the frond stalks, meaning silver ferns are easily identified by their trunks alone.
- It is widespread and common in the North Island. In the South Island, it occurs in the very north and sparingly along the east coast, but is absent from the west and south. Te Papa’s collections of silver fern specimens, with map.
- Silver ferns prefer warm, dry habitats, contrasting with the other prominent tree ferns in New Zealand: mamaku – warm & wet; katote – cool & wet; wheki – wet ground; wheki-ponga – cool & dry. But it is not unusual to find most/all of these species in close proximity. Silver ferns flourish under teatree (manuka/kanuka) and other scrubs in the northern lowlands.
- Traditional uses of ponga included as building material, treating skin problems, marking tracks for night-time use, and the trunk’s woody fibre was used to make poisonous spear tips.
- The silver fern is indigenous only to New Zealand (North and South Islands, and many of the offshore islands, as well as the Chatham Islands).
- A very similar species, Cyathea milnei, occurs on the Kermadec Islands to the north-east of the North Island. However, its frond undersides are green rather than white/silver.
- Another similar and seemingly closely related species, Cyathea australis, occurs in Australia and Norfolk Island. Its frond undersides are also green rather than white/silver. Additionally, its reproductive structures are naked rather than demurely covered as in the silver fern.