N.Is.: between Palm Glen and Red Rd, M.Lazarides 8091 (CANB, K); Ball Bay, P.S.Green 2402 (K); s. loc., A.Cunningham 29(51) (K); s. loc., I.Robinson 12 (MEL).
Hybrids between this species and A. difforme can occur (Norfolk Is., s. loc., R.M.Laing, CHR). In these the 'fertile', linear pinnules are generally shorter and broader than in A. dimorphum (3–7 × 2–3 mm long versus 5–15 × 1–2 mm), and the sterile pinnules are somewhat intermediate between the two species in shape and texture.
Asplenium oblongifolium Colenso was recorded from Norfolk Is. as A. lucidum G.Forst. (non Burm.f.) by W.J.Hooker (Sp. Fil. 3: 98, 1860), attributing a collection to Dr. Vaughan Thomson, without any further locality, date etc. However, the only specimen at Kew marked 'Norfolk Island' and bearing Thomson's name in Hooker's hand (and stamped 'Herb. Hook. 1867') is a single frond mounted on the same sheet as Colenso 60, labelled '60 Asplenium oblongifolium n.sp. W.C.' in Colenso's hand; this latter is from New Zealand, and possibly an isotype of Colenso's species. With no further collections of this species having been made from Norfolk Is., the frond attributed to Thomson must be assumed to have been mislabelled.
P.S.GreenRoyal Botanic Gardens, Kew, Richmond, Surrey, TW9 3AB, England
Terrestrial ferns. Rhizomes with pale or dark, non-clathrate, entire or toothed scales. Fronds simple to 4-pinnate; rachis and costae grooved above; veins free or reticulate, the areoles without free included veinlets. Sori elliptic to elongate-linear, along one or both sides of a vein; indusia narrow (elsewhere absent), following the sori, sometimes double, back to back (especially on basal pinnae).
A worldwide family of c. 8 genera and c. 650 species; 2 genera native on Norfolk Is., 1 of which is also on Lord Howe Is.
Generic delimitation and classification in this family is a matter of debate.
Grooves on rachis above, not confluent at junction with costae; fronds borne along a creeping rhizome, pinnate, deeply pinnatisect
DiplaziumSw. J. Bot. (Schrader) 1800(2): 61(1801) from the Greek diplasios (double), in reference to the frequently double sori in these ferns
Type: D. plantagineum (L.) Sw.
Terrestrial ferns. Rhizome erect, usually short. Stipes sometimes rough at base. Fronds (simple to) 2–4-pinnate, glabrous; rachis and costae with grooves confluent and open at their junctions, glabrous; veins free or reticulate. Sori elliptic or linear, sometimes double along both sides of vein.
A large genus of c. 400 species, mainly tropical, and distributed widely; 2 species native to Norfolk Is., 1 species endemic on Lord Howe Is.
1 Pinnules narrowed at base; larger secondary pinnules 2–5 cm long (N.Is.)
1. D. assimile
1: Pinnules not narrowed at base; larger secondary pinnules 3–10 cm long
2 Sori lightish brown, 1–2 mm long (N.Is.)
2. D. australe
2: Sori very dark brown, 2–4 mm long (L.H.Is.)
3. D. melanochlamys
assimile(Endl.) Bedd. Ferns Brit. India t. 294(1868)
Asplenium assimile Endl., Prodr. Fl. Norfolk. 10 (1833); Athyrium assimile (Endl.) C.Presl, Tent. Pterid. 98 (1836); Asplenium umbrosum var. assimile (Endl.) Hook. & Baker, Syn. Fil. 2nd edn, 489 (1874); Diplazium umbrosum var. assimile (Endl.) Bedd., Handb. Ferns Brit. India 190 (1883).T: Norfolk Island, 1804–1805, F.L.Bauer; holo: W. The epithet is from the Latin assimilis (dissimilar), but the meaning is obscure.
[Athyrium umbrosum auct. non (Aiton) C.Presl: J.H.Maiden, Proc. Linn. Soc. New South Wales 28: 735 (1904); R.M.Laing, Trans. & Proc. New Zealand Inst. 47: 11 (1915)]
Illustrations: D.L.Jones & S.C.Clemesha, Austral. Ferns & Fern Allies 2nd edn, 127, fig. 144 (1981); S.B.Andrews, Ferns Queensland 77, fig. 5.2A (1990); P.G.Wilson in G.J.Harden, Fl. New South Wales 1: 58 (1990).
Rhizome ±erect. Fronds tripinnate; stipe 15–50 cm tall, light brown shading to black at base, with brown scales 3–5 mm long at base; lamina broadly triangular in outline, 30–60 cm long, 25–40 cm broad; larger secondary pinnae 2–5 cm long, with 4–8 separate pinnules; pinnules 5–10 mm long, narrowed at base, decurrent onto the very narrowly winged costule, bluntly toothed at margin, blunt at apex. Sori elongate, 1–3 mm long, (2–) 3 or 4 per pinnule side, rarely the basal sori doubled; indusia light brown.