Blechnum revolutum
Content
Distribution
Asia-Tropical: Philippines (Philippines present), Central Papua New Guinea present, E Highlands present, Madang present, Mindanao present, Morobe present, Papua New Guinea present, S Highlands present, W Highlands present, W Sepik present
Malesia: Philippines (Mindanao), Papua New Guinea (W Sepik, Madang, W Highlands, E Highlands, Morobe, S Highlands, Central Papua New Guinea) where it is a distinctive species frequently with a robust erect caudex up to 1 m tall.
Notes
1. The creeping underground rhizomes and repeated vegetative reproduction of B. revolutum due to the decay of the rhizomes and the creation of separate plants probably account for the local abundance, sometimes dominance, of this species.
2. Blechnum revolutum is usually readily separated from other species of the genus in the New Guinea area by the very strongly revolute sterile pinnae, their subpetiolate attachment to the rhachis and the persistently densely scaly nature of most of the plant. These general features are also to be found in the tropical montane South American species B. loxense (Humb., Bonpl. & Kunth) Hieron., but the two can be separated by the nature of their scales. The South American species, while showing more variability, has basal stipe scales which are much thinner, more fragile, papery, and generally paler while those of the rhachis and costae tend to have paler fringed margins and small dark centres.
3. Some Papua New Guinea specimens of B. revolutum, especially when growing in protected areas such as edges of lower subalpine and montane rain forest, have sterile pinnae which are not markedly revolute or may be only very finely revolute at the pinna margin. The pinnae are therefore flat rather than inrolled. Such specimens may be confused with B. hieronymi but the large broad dark reddish brown scales at the base of the stipe indicate they belong with B. revolutum, e.g. Croft (et al.) LAE 61669, from the margin of lower subalpine rain forest and Isuani grassland, has these less typical characters.
2. Blechnum revolutum is usually readily separated from other species of the genus in the New Guinea area by the very strongly revolute sterile pinnae, their subpetiolate attachment to the rhachis and the persistently densely scaly nature of most of the plant. These general features are also to be found in the tropical montane South American species B. loxense (Humb., Bonpl. & Kunth) Hieron., but the two can be separated by the nature of their scales. The South American species, while showing more variability, has basal stipe scales which are much thinner, more fragile, papery, and generally paler while those of the rhachis and costae tend to have paler fringed margins and small dark centres.
3. Some Papua New Guinea specimens of B. revolutum, especially when growing in protected areas such as edges of lower subalpine and montane rain forest, have sterile pinnae which are not markedly revolute or may be only very finely revolute at the pinna margin. The pinnae are therefore flat rather than inrolled. Such specimens may be confused with B. hieronymi but the large broad dark reddish brown scales at the base of the stipe indicate they belong with B. revolutum, e.g. Croft (et al.) LAE 61669, from the margin of lower subalpine rain forest and Isuani grassland, has these less typical characters.