Blechnum fraseri

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Blechnum fraseri

Distribution

Asia-Temperate: Taiwan (Taiwan present), Asia-Tropical: Borneo present (Sabah present); Malaya (Peninsular Malaysia present); Philippines (Philippines present); Sumatera (Sumatera present), Luzon present, Mindoro present, Mt Kinabalu present, New Ireland present, New Zealand where it occurs from latitude 35° S of the North Island to latitude 42° S in the South Island, west of the Southern Alps present, Papua New Guinea present, W Highlands present
Malesia: Widespread but very localised in mountain areas extending from Sumatra and Peninsular Malaysia to Borneo (Sabah: Mt Kinabalu), Philippines (Luzon, Mindoro) south to Papua New Guinea (W Highlands, New Ireland). Outside Malesia: The species also extends north to Taiwan and south to New Zealand where it occurs from latitude 35° S of the North Island to latitude 42° S in the South Island, west of the Southern Alps.

Notes

1. Blechnum fraseri was named in honour of Mr Charles Fraser who, when Superintendent of the Sydney Botanic Gardens and Colonial Botanist between 1816 and 1831, first collected this attractive species in New Zealand.
2. The frond of B. fraseri is unusual in possessing conspicuous triangular toothed wings adnate to and on either side of the rhachis and alternating with the pinnae.
3. Blechnum fraseri is rarely found as single isolated plant but rather as a gregarious community dominating areas ranging from a few square metres to several hundred square metres of the forest floor and sometimes at the margins of forests. This is at least partly the result of reproducing vegetatively by means of short underground rhizomes giving rise sympodially to new trunks. The underground rhizomes usually decay quite early in development and so colonies are rarely found with obvious interconnecting structures.
4. The species appears to require reasonably high light and hence is found in more open forest associations especially on ridges. In the northern part of the North Island of New Zealand it is often associated with the relatively xeric forest floor communities in mature stands of Agathis australis Salisb.
5. Three taxa within this species have been variously recognised as distinctive: Blechnum fraseri from New Zealand, B. fraseri var. philippinense from the Philippines, E Malaysia (Sabah in N Borneo), Indonesia (Sumatra), Papua New Guinea (mainland and New Ireland), and B. integripinnulum from Taiwan.
6. Our study of B. fraseri, B. fraseri var. philippinense, and B. integripinnulum has not revealed any consistent morphological characters that would justify reliable separation into three taxa. Tropical plants referred to as var. philippinense are sometimes slightly larger, with broader sterile segments and more well-developed triangular adnate wings to the rhachis, and a tendency on many fronds for the lamina to be less abruptly reduced towards the base. However, we have not been able to separate specimens from New Zealand growing in very favourable situations in temperate lowland forests from the taxon referred to as var. philippinense from tropical mountain habitats. Conversely several specimens from the tropical areas closely approach the morphology of much of the New Zealand material, e.g. Jacobs 7159, Mt Pulog (L) and M.G. Price 433, Mt Polis (L), both from Luzon, while a specimen from Mt Halcon, Mindoro, E.D. Merrill 5906 (L) is intermediate between the tropical and temperate zone forms. It seems likely therefore that the morphology of the variety is a response to environmental conditions and we have concluded that there is only one recognisable taxon, B. fraseri.
7. The spores perhaps indicate some minor genetic difference in that in the New Zealand B. fraseri spores the scabrous outer coat tends to persist and the verrucae are not as pronounced as they are in Malesian specimens; in the latter the scabrous layer tends to disintegrate and expose the microreticulations of the verrucae but this could be a response to the tropical environment and the methods of specimen preparation. We have not examined spores of the Taiwan material.
8. Two pencil drawings of enlarged fertile pinnae attached to the undated Fraser specimen at K suggest that this is the specimen from which Hooker’s. Icon. Pl. (1837) t. 185 was prepared. Fraser’s 1826 specimen at K, ‘ex Allan Cunningham, N.Z. Herb. presented by R. Heward 1862’, could well be part of the type collection. The other specimen at K was cited by Cunningham and is the lectotype here chosen.
9. Other types: Fraser, no date; residual syntypes: K (2 specimens: ‘185 Stegania Fraseri Bay of Islands off the East Coast of N.Z. C. Fraser 1826’ and ‘At Wangaroa, Waimate and Hokianga, in dense forests R. Cunningham 1834’).

Citation

A.G.Piggott & C.J.Piggott 1988: Ferns of Malaysia in colour: 406. pl. 1245-1249
T.C.Chambers & P.A.Farrant 2001 – In: Blumea. p 306
Cheeseman 1914 – In: Ill. New Zealand Fl. pl. 242
Hook. 1837: Icon. Pl. t. 185
Crookes & Dobbie 1963: New Zealand Ferns, 6th ed. p 305
Ogata 1940 – In: Icon. Fil. Jap. pl. 360
Brownsey & J.C.Smith-Dodsworth 1989: New Zealand Ferns & Allied Plants: 143. f. 180, pl. 33B