N.Is.: high ground, W.G.Milne 10 (K); Now-Now Valley, R.M.Laing (CHR). L.H.Is.: Old Settlement area, A.C.Beauglehole 5388 (MEL); E side of North Hummock, A.C.Beauglehole 5589 (MEL); high ground, W.G.Milne 35 (K).
The Lord Howe Is. plant has been said to have a narrower, more erect habit, with thicker, more obtuse, glaucous fronds than those elsewhere, but more comparative observations are required.
Fronds from a small (?juvenile) plant with the lamina deeply cut into a few irregular lobes has been collected on Lord Howe Is. (A.C.Beauglehole 5411, MEL, NSW).
1b. Asplenium australasicum f. robinsonii (F.Muell.) P.S.Green in
Kew Bull. 43: 649(1988)
Asplenium robinsonii F.Muell., J. Bot. 22: 289 (1884).T: Norfolk Island, I.Robinson; holo: ?MEL n.v.; iso: BM, K. Named after Isaac Robinson, resident on Norfolk Is., who collected extensively there in the latter half of the 19th century for the Botanic Gardens, Sydney.
Generally somewhat smaller than the typical form but with the fronds crisped and/or occasionally, and irregularly, deeply cut or, rarely, proliferating.
Crispy Bird's Nest Fern.
Norfolk Is. Now only known in cultivation. It has been recorded from the eastern slopes of Mt Gower, Lord Howe Is. (J.H.Maiden, Proc. Linn. Soc. New South Wales 23: 146, 1898), but the specimen appears to have been lost.
When grown from spores, most sporelings develop into typical Asplenium australasicum.
milneiCarruth. in B.C.Seemann Fl. Vit. 353(1873)
T: Lord Howe Island, 'Macrae' [Milne?]; holo: ?BM n.v. Named after William Grant Milne (?–1866), botanist on the Herald expedition in the south-western Pacific (1852–1856), who collected on Lord Howe Is. in 1853.
[Asplenium obtusatum var. lucidum auct. non (G.Forst.) Hook. & Baker: W.J.Hooker & J.G.Baker, Syn. Fil. 207 (1867), p.p.]
[Asplenium lucidum auct. non G.Forst.: C.Moore in E.S.Hill, Votes & Proc. Legislative Assembly New South Wales 26 (1870)]
[Asplenium marinum auct. non L.: F.J.H. von Mueller, Fragm. 9: 78 (1875)]
[Asplenium obtusatum auct. non G.Forst.: W.B.Hemsley, Ann. Bot. (London) 10: 264 (1896)]
Illustrations: C.J.Goudey, Austral. Fern J. 1:  t. 7 (1984); D.L.Jones, Encycl. Ferns 229 (1987).
Terrestrial fern. Rhizome stout; scales dense, lanceolate, clathrate. Fronds pinnate; stipe 15–24 cm long, dark brown, densely covered with small, clathrate, dark brown scales, especially towards base, often rubbed off; lamina 10–60 cm long, 5–25 cm broad, shining; pinnae 11–18 per side, narrowly lanceolate (to ovate), asymmetrically cuneate at base, (2–) 5–15 cm long, 1–2 cm broad, rarely once divided to the costae at base, ±evenly serrate, usually contracting to an acute apex from c. the middle; rachis and costae below with scattered, small, dark brown scales. Sori linear, 5–10 mm long, following a lateral nerve with a branch nerve between.
Lord Howe Is. Endemic.
Common in the lowland forest.
L.H.Is.: lower slopes of Malabar, P.S.Green 1544A (K); above E end of North Beach, A.N.Rodd 1755 (K, NSW); near the Goathouse, R.D.Hoogland 8815 (CANB); s. loc., W.G.Milne 25 (K).
This is a species closely related to Asplenium oblongifolium Colenso (A. lucidum G.Forst. non Burm.f.) of New Zealand, and A. obtusatum G.Forst. of eastern Australia and New Zealand. A hybrid with A. polyodon G.Forst., recorded on the field notes as 'rare', has been collected once (J.Pickard 2711, Boat Harbour track, Dec. 1975, K, NSW). In addition, a hybrid with A. surrogatum P.S.Green has once been collected. This was by Chris Goudey from beside the track to Boat Harbour; I have seen a specimen cultivated from this plant.
difformeR.Br. Prodr. 151(1810)
Asplenium obtusatum var. difforme (R.Br.) Hook., Sp. Fil. 3: 97 (1860).T: Botany Bay, Australia, J.Banks & D.Solander; holo: ?BM n.v. The epithet comes from the Latin dis- (apart) and forma (shape), in allusion to the distinct fronds in this fern.
Asplenium obtusatum var.: W.J.Hooker, Fil. Exot. t. 46 (1859).
Illustrations: D.L.Jones & S.C.Clemesha, Austral. Ferns & Fern Allies 2nd edn, 88, fig. 75a (1981); S.B.Andrews, Ferns Queensland 59, fig. 4.5A (1990), as A. obtusatum var. difforme; P.G.Wilson in G.J.Harden, Fl. New South Wales 1: 55 (1990).
Terrestrial fern. Rhizome short, tufted; scales narrow, to c. 1.5 cm long, long-pointed, clathrate. Fronds pinnate to bipinnate, ±coriaceous, discolorous, glabrous; stipe 2–15 cm long, glabrous except for occasional, almost linear, clathrate scales; upper half of rachis not winged; lamina 3–30 (–40) cm long, (2–) 3–10 (–15) cm broad, with scattered, almost linear, clathrate scales; pinnae (3–) 5–10 (–15) per side, lanceolate to deltoid-lanceolate in outline, bluntly serrate to pinnatifid or bipinnate, 1–5 (–10) cm long, (0.7–) 1.5–2.5 cm broad; fertile pinnules 4–12 mm broad. Sori oblong-linear, 3–6 mm long, along lateral veins, almost marginal in bipinnate fronds.
Coastal Fern, Coastal Asplenium.
Norfolk Is. Also known from N.S.W. and southern Qld.