Blechnum fluviatile

Blechnum fluviatile is a fern known in the Maori language as kiwikiwi. Ladderlike fronds of B. fluviatile measure up to 50 cm (20 in) long. Growing in a distinctive ground-hugging rosette shape, its fertile fronds – dark brown and spiky – stand upright from the centre, while the drooping sterile fronds with their nearly round leaflets, form the rosette. As the parent plant ages it develops a short trunk central to a surrounding colony.