Blechnum fluviatile
Content
Distribution
Asia-Tropical: Borneo present (Sabah present); Philippines (Philippines present); Sumatera (Sumatera present), Atjeh present, Central Papua present, E Highlands present, Gajolanden present, Madang present, Milne Bay present, Morobe present, Mt Kinabalu present, New Zealand present, Papua New Guinea present, S Highlands present, SE Australia present, W Highlands present
Malesia: Sumatra (Atjeh, Gajolanden), Borneo (Sabah: Mt Kinabalu), Philippines, (one specimen at Leiden (L908.316-471) labelled ‘Polybotryo Hamiltonia Hook.’ ‘Ex insul Philipp. Cuming’, although only a fragment, has sterile and fertile fronds of B. fluviatile), Papua New Guinea (Madang, W Highlands, E Highlands, Morobe, S Highlands, Central Papua, Milne Bay). Outside Malesia: SE Australia and New Zealand.
Cytology
Variable, 2n = 66 in the North Island of New Zealand and in New South Wales and Victoria (Chambers unpubl. data). All populations sampled from the South Island from forested lowland and submontane to montane vegetation are tetraploid with the sporophytic number 4n = 132 (); Tasmanian populations sampled by Quinn () all exhibited a triploid condition, the sporophyte number being 3n = 99. It has not been possible to detect any consistent morphological differences between these various populations even where some of them have been grown in cultivation under the same conditions. It would be interesting to have cytological data on the Malesian populations.
Notes
1. The plants described by Copeland as B. nudius are extreme ecological variants of B. fluviatile. The isotype at Leiden has a long slender trunk and also exhibits exceptionally long stipes (15 cm) with a lamina only 25 cm in length. A note on a specimen collected by Croft (LAE 61831) from Isuani grassland (SE slopes Mt Victoria, subdistrict Port Moresby 2700 m, 8°55'S, 147°35'E) confirms this interpretation. This specimen comes from swampy grassland and is very similar to the specimen described by Copeland.
2. Although B. fluviatile exhibits considerable variation, especially in the size of fronds and spacing and shape of pinnae, this is a well-circumscribed and probably long isolated species; it does not appear to have any particularly closely related species in the genus. The character of the juvenile plants and of very stunted plants could be confused with forms of B. membranaceum (Colenso) Mett. (a species from New Zealand) and for this reason together with its diploid chromosome number of 2n = 66 it will be placed with this group of species.
3. The species in cultivation is not tolerant of high light conditions which results in a yellowing of the pinnae. In nature, forest and forest edge specimens are usually in at least partial shade while those from more alpine habitats although exposed to full sky light are mostly found growing in areas of frequent cloud and mist.
2. Although B. fluviatile exhibits considerable variation, especially in the size of fronds and spacing and shape of pinnae, this is a well-circumscribed and probably long isolated species; it does not appear to have any particularly closely related species in the genus. The character of the juvenile plants and of very stunted plants could be confused with forms of B. membranaceum (Colenso) Mett. (a species from New Zealand) and for this reason together with its diploid chromosome number of 2n = 66 it will be placed with this group of species.
3. The species in cultivation is not tolerant of high light conditions which results in a yellowing of the pinnae. In nature, forest and forest edge specimens are usually in at least partial shade while those from more alpine habitats although exposed to full sky light are mostly found growing in areas of frequent cloud and mist.
Citation
B.D.Duncan & G.Isaac 1986: Ferns & Allied Plants Victoria, Tasmania & S Australia: 209: f. 20.10
Salomon 2001 – In: Blumea: 303
T.C.Chambers & P.A.Farrant 1998: p. 371. – In: Fl. Australia: f. 125E, map 336
Crookes & Dobbie 1963: New Zealand Ferns, 6th ed: 301
Brownsey & J.C.Smith-Dodsworth 1989: New Zealand Ferns & Allied Plants: 143: f. 179, pl. 33A
Copel. 1949: p. 226. – In: Philipp. J. Sci.: pl. 6