Adiantum diaphanum

Filmy maidenhair fern

Family: Pteridaceae

A rhizomatous perennial fern, with fronds to about 40 cm tall.

It grows in rainforest, often along streams or near waterfalls, mainly found on the NSW Coast and slightly into the ranges, north mostly from around Nowra but also with records at Mt Dromedary (near Tilba Tilba). It occurs in Victoria in one patch (disjunct from the NSW occurrences) to the south-east of Melbourne in the Strzelecki Ranges. It extends into Queensland, up the coast and tablelands, in disjunct patches, as far as Cape York Peninsula. Also grows in NZ as well as the Pacific Islands.

The rhizomes are short, covered with reddish brown scales; rootlets with small, prominent, brown bulbils.

Adiantum spp. can present with a variety of frond-appearances. In this species, the fronds grow to about 40 cm tall, are considered compound-pinnate, being divided into 2 or 3 frond sections, made up of segments. The segments (pinnules/leaflets) are to 13 mm long and about 6 mm wide, pale to dark green, roughly elliptic to asymmetrical in shape. Terminal growth can have stiff black or brown hairs.

Being a fern, no flowers or fruits are produced. Rather, spores are produced.

Spores are produced in sporangia, which are housed in a sorus (plural sori). The sori are produced on the underside of frond segments and follow the segment edges, round to kidney-shaped. There can be up to 8 sori per segment.

In the garden

This species is not cultivated commonly but there are websites suggesting cultivation (see references).

Grows best in well moist, drained and humus-rich soils in dappled light.

Scale can be a problem as well as Maidenhair aphids.

During winter it needs to be cut back hard to encourage new and attractive green-spring growth.

Susceptible to leaf burn in low humidity or when soil dries out.


Propagation is from plant division or by spores.

Other information

Not likely to be affected by fires, given its habitat. Fire response unknown.

Adiantum is a genus of around 200 species – cosmopolitan in distribution. Australia reportedly has around 8 species, found in all states and territories. NSW currently has 7 species.

Adiantum – from the Greek adianton (ἀδίαντον) meaning “not wetting” or “un-wet-table, referring to the fronds’ ability to shed water without becoming wet, likely due to the waxy surface of the segments.

diaphanum – from the Greek diaphanes (διαφάνεs), meaning “transparent” or “filmy”, which assumingly pertains to the fronds when held against the light.

This species is not considered to be at risk of extinction over most of its habitat. It is listed as Critically Endangered in Victoria but not elsewhere in the wild.

NSW Flora Online (PlantNET) – Adiantum diaphanum profile page https://plantnet.rbgsyd.nsw.gov.au/cgi-bin/NSWfl.pl?page=nswfl&lvl=sp&name=Adiantum~diaphanum

VICFlora – Flora of Victoria Online – Adiantum diaphanum profile page https://vicflora.rbg.vic.gov.au/flora/taxon/6d29b789-436a-44f1-ba5f-829f54d29278

University of Auckland – New Zealand Plants – Adiantum diaphanum profile page http://www.nzplants.auckland.ac.nz/en/about/ferns/native-ferns/pteridaceae-maidenhair-annual-rock-brake-ferns/adiantum-diaphanum.html

By Jeff Howes. Editing and additional text by Dan Clarke