Pyrrosia elaeagnifolia (Bory) Hovenkamp

Epiphytic and terrestrial; creeping and climbing ferns.  Rhizomes long-creeping, 0.75–2 mm diameter, scaly.  Rhizome scales non-clathrate, narrowly ovate, 2–7 mm long, 0.5–1 mm wide, squarrose, orange-brown when young, entire or sometimes denticulate.  Stipes winged for most of their length and indistinct from the attenuate lamina base.  Fronds undivided, very varied in shape; the sterile almost orbicular to elliptic, obovate or spathulate, 20–180 mm long (including stipe), 11–31 mm wide; the fertile narrowly obovate to spathulate or sometimes narrowly elliptic to linear, 30–260 mm long (including stipe), 4–20 mm wide; apex obtuse to rounded; margins entire; base attenuate to an indistinct stipe; dark green; coriaceous to succulent; scattered stellate hairs on adaxial surface, densely covered in fawn or rarely silver coloured stellate hairs on abaxial surface.  Veins obscure; hydathodes absent.  Sori round or slightly elongate, 2–4 mm long, superficial or partly impressed into the lamina but not or rarely bulging on adaxial surface, irregularly arranged in 2–5 rows (rarely 1) either side of midrib, rarely almost confluent with age, occasionally confined to distal part of lamina; paraphyses present as stellate hairs; exindusiate.

This species is easily recognised by its thick, fleshy, undivided fronds, dense covering of usually fawn-coloured stellate hairs, and exindusiate sori normally arranged in several rows either side of the midrib.  

Very occasional aberrant fronds are found with lobed or bifid fronds, and sometimes the rhizome apices are fastigiately divided into multiple growing tips.  The latter has been attributed to a gall-forming mite, Aceria sp. (Hovenkamp 1986, p. 178).

This is a very tough and adaptable fern which can survive dry conditions due to its fleshy frond, dense covering of hairs and reduced lamina area.  It occurs on rocks, logs, scoria and banks, and as an epiphyte on branches and trunks of native, naturalised and cultivated trees.  It is found from exposed coastal situations to sheltered forest, in a wide range of scrub, beech, podocarp and broadleaved forest types.

n = 37 (Brownlie 1961, as Pyrrosia serpens).

New Zealand plants were previously referred to P. serpens (G.Forst.) Ching, but that species has larger sori in just 1–2 rows either side of the costa.  The confusion arose because Forster identified New Zealand as the type locality for P. serpens, but his specimen is not conspecific with the local species.  It was probably collected on one of the Pacific islands, and the specimen mis-labelled (Hovenkamp 1986).  P. serpens occurs across the Pacific from New Caledonia to Pitcairn Island.

Pyrrosia eleagnifolia has been widely misidentified in earlier New Zealand literature under the names Polypodium stellatum Vahl, Polypodium serpens G.Forst., Niphobolus bicolor Kaulf., and Polypodium rupestre R.Br. (and combinations based on them).   

Hovenkamp (1986) noted that specimens from the Kermadec Islands have rhizome scales that are more strongly dentate than those from elsewhere.  Sometimes, they also have larger sterile fronds with silver coloured hairs (e.g. AK 234205).  Whether these differences warrant taxonomic recognition needs further investigation.