Fastest-growing tree fern

The world's fastest-growing tree ferns are the Norfolk tree fern (Cyathea brownii = Sphaeropteris excelsa), endemic to Norfolk Island, situated between Australia and New Zealand in the Pacific Ocean, and a close relative, the black tree fern (Cyathea medullaris = Sphaeropteris medullaris), distributed widely across the islands of the south-west Pacific, but particularly common in New Zealand. Both ferns can grow as much as 50 cm (1 ft 7 in) per year.

These species belong to the scaly tree fern family, Cyathaeceae, which is the largest tree fern family, containing roughly 640 species. Moreover, it is a very ancient family, first appearing in the fossil record as far back as the Late Jurassic period, approximately 161–143 million years ago.