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Flora of Australia Online

Asplenium australasicum (J.Sm.) Hook., Fil. Exot. t. 88 (1858)
Bird's Nest Fern

Neottopteris australasica J.Sm., Cult. Ferns 49 (1857); Thamnopteris australasica (J.Sm.) T.Moore, Index Fil. 115 (1859). T: from an Australian plant cultivated at Kew, England; holo: BM.

Illustrations: D.L.Jones & S.C.Clemesha, Austral. Ferns & Fern Allies 2nd edn, 82, fig. 66 (1981); D.L.Jones, Encycl. Ferns 225 (1987); S.B.Andrews, Ferns Queensland 54, fig. 4.3B (1990).

Ferns with nest-like habit. Rhizome erect, scaly, unbranched with a single growing point. Fronds ±straight, arising in a regular rosette at a small angle to vertical. Stipe indistinct, 1–3 cm long, 6–15 mm wide. Rachis in cross-section flat on upper surface, strongly keeled below. Lamina narrowly obovate, simple, 50–175 cm long, 6–19 cm wide, shiny green, ±glabrous; bases narrowly cuneate; margins entire; apices acute or obtuse; veins free except for a marginal connection. Sori very numerous, close together; longest 16–60 mm long, extending from midrib, usually occupying more than half the width of the lamina. Perispores pale with fimbriate broad ridges and fenestrate lacunae; exospores 44.1–47.9 × 27.6–32.8 µm (means). 

Occurs near the east coast from McIlwraith Range, north-eastern Qld to south-eastern N.S.W.; also Norfolk Is., Lord Howe Is., New Guinea, New Caledonia, Fiji, Samoa, Tonga and Tahiti. Common as an epiphyte on tree trunks, or on rocks or banks in rainforest and wet sclerophyll forest, producing a large nest-like growth form. Map 276.

Qld: Mt Lewis, S.B.Andrews 258 & G.Stocker (BRI); Upper Coomera Track, Lamington Natl Park, S.T.Blake 20581 (BRI). N.S.W.: Orara State Forest, Coffs Harbour, 2 May 1956, E.F.Constable (NSW).

Specimens from northern Qld are generally smaller than those from further south, with the stipe 1–5 cm long and 4–8 mm wide, the lamina 35–80 cm long and 8–15 cm wide and the sori 13–40 mm long. Although previously confused with A. nidus, A. australasicum can be distinguished easily by its strongly keeled rachis on the underside.

(P.J.Brownsey)

 

Data derived from Flora of Australia Volume 48 (1998), a product of ABRS, ©Commonwealth of Australia