Blechnum rosenstockii

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Blechnum rosenstockii


Asia-Tropical: New Guinea present; Sulawesi (Sulawesi present), Morobe present, New Ireland present, Papua New Guinea present, S Highlands present, W Highlands present, W Sepik present
Malesia: Sulawesi, New Guinea (Papua New Guinea: W Sepik, W Highlands, Morobe, S Highlands, New Ireland). A rarely collected species from the highlands; all collections are from above 2000 m.


1. A little known species. The few collections come from widely separated areas, extending from Papua New Guinea to Sulawesi. It seems likely that new localities will be found, most likely in ecologically comparable areas of the region.
2. The slender caudex of B. rosenstockii is not usually sufficiently rigid for supporting the crown of fronds in an upright position and this results in the plant exhibiting a sprawling habit. Blechnum fraseri has a more rigid caudex holding the crown of fronds in an erect position. Both species tend to have a colonial habit, resulting in a miniature forest of these plants as an understorey of a taller forest.
3. Kjellberg in his description of B. tengwallii from Celebes (Sulawesi) described the plant with an erect trunk up to 1 m and more or less 1 cm diam. with the fronds aggregated at the apex, suberect or spreading, the sterile up to 60 by 7 cm narrowed to both ends pinnate or subpinnate slender and bright green. However, Copeland had already named this species as B. rosenstockii from a New Guinea collection. He based his original description on an incomplete specimen “because of its exceptional interest, it being the first form known to me intermediate between the body of the genus and the hitherto very isolated Blechnum Fraseri”. The holotype consists of an isolated fertile frond 45 by 5 cm broad; the pinnae bases are triangular 0.25 cm across spreading along the rhachis.
4. Croft has pointed out that the material at LAE reveals no intermediates with B. fraseri and that “on the three occasions when [he had] seen it in the field, although both species occurred together, no intermediates could be found” (Croft pers. comm.).
5. Blechnum rosenstockii is undoubtedly closely related to B. fraseri not only because of the similar spores (the verrucae in B. rosenstockii are even more prominent) but also they share rhizomes of similar appearance, develop a comparable caudex and have similar rhizome scale characteristics.
6. Blechnum rosenstockii de la Sota, Darwiniana 18 (1973) 254, t. 6, 7a is a later homonym.


T.C.Chambers & P.A.Farrant 2001 – In: Blumea. p 332