Nephrolepis biserrata

Nephrolepidaceae

Nephrolepis biserrata (Sw.) Schott

Link to Australian Plant Name Index for publication details and synonyms: https://id.biodiversity.org.au/name/apni/82014

Sword Fern or Fishbone Fern

Stolons and basal portions of stipes scaly; scales lanceolate, red-brown, with few to many short or long marginal cilia. Fronds to 2.5 m or more long; rachis with scattered hair-like scales and/or simple hairs, glabrescent. Pinnae relatively widely-spaced, sometimes with a small rounded auricle. Sterile pinnae 25–120 mm long, 8–30 mm wide, usually glabrous, occasionally with ciliate scales; base often obliquely truncate; margins shallowly crenate; midrib sometimes with simple hairs. Fertile pinnae 100–240 mm long, 10–30 mm wide; margins more deeply crenate. Sori between half and two-thirds distance from midrib to margin; indusium reniform. 

Scattered across coastal and inland areas of tropical QLD, NT and WA, usually north of latitude 19 S. Pantropical.

Terrestrial, occasionally lithophytic, in rainforest, rainforest margins and open forest. In inland areas it is usually found in creeks and gorges.

A very large fern that is widely cultivated. It can be invasive in greenhouse and garden situations.

Readily cultivated in a wide range of situations. Can be a weed.

Nephrolepis biserrata can be distinguished from other Australian Nephrolepis by the medial location of sori and by the relatively entire pinnae margins without a basal auricle.

Key to Australian Nephrolepis spp.:
1a. Sori linear with a linear indusium and borne on margin; pinnae with entire margins = Nephrolepis acutifolia
1b. Sori round or kidney-shaped with a kidney-shaped indusium and borne supramedially to medially, each on the end of a vein, margins ~ crenate = 2
2a. Pinnae with an obtuse apex, less than 50 mm long = 3
2b. Pinnae with an acute to attenuate apex, greater than 50 mm long = 4
3a. Rachis with scales, rarely hairy, basal auricles of pinnae overlapping rachis = Nephrolepis cordifolia
3b. Rachis with hairs, rarely scaley, basal auricles of pinnae not usually overlapping rachis = Nephrolepis arida
4a. Pinnae with an acroscopic basal auricle; all parts hirsute = 5
4b. Pinnae lacking a distinct acroscopic basal auricle, indumentum sparse = 5
5a. Hairs on upper side of costae absent; rachis scales rufous, with strongly dentate acumen; sori submarginal = Nephrolepis hirsutula
5b. Hairs on upper side of costa present; rachis scales hyaline or light brown (rarely rufous), with nearly entire acumen; sori submedial = Nephrolepis brownii
6a. Sori borne close to margin, stolons densely scaly = Nephrolepis biserrata
6b Sori borne medially, stolons green with few scales = Nephrolepis obliterata