T.E.R:R.A.I.N - Taranaki Educational Resource: Research, Analysis and Information Network


Adiantum formosum (Giant Maidenhair)

Kingdom: Plantae
Division: Pteridophyta
Class: Pteridopsida
Order: Polypodiales
Family: Pteridaceae
Genus: Adiantum
Species: A. formosum
Binomial name: Adiantum formosum
Common names: Giant Maidenhair, Plumed maidenhair, Black Stem Maidenhair.

Adiantum formosum a tall, widely creeping fern found in Australia and New Zealand. It is very rare in the wild in New Zealand but common in Australia. It is common in cultivation. It has been in the past recorded from Tauroa (Reef Point) and Herekino, North Wairoa River in Northland and from D’Urville Island but now confined to the Manawatu River Gorge and in forest near the eastern and western ends, as well as around Woodville, growing in moist shaded areas along streams usually on alluvial soils.
Its species name is the Latin adjective formosus "handsome" or "beautiful". Adiantum formosum has fronds up to 120 cm high. The rhizome of this species is unusually deep, up to 60 cm below into the earth. The stems are black and can reach 90 cm in length, while the fronds or blades are triangular with rectangular segments. The last segment of the frond is irregular and asymmetrical, on a short stem. This maidenhair fern can grow to 2 metres tall. The smallest segments of the fronds are the pinnules, which are wedge-shaped, rectangular or trapezoid. They have 1–10 sori along the margins underneath.





Topside of frond


Underside of frond