Appearance
The trunk of this species is erect and may be as tall as 5 m or more. Fronds are bi- or tripinnate and usually 2–3 m long. The rachis is long, dark to black in colouration and rough in appearance after the fall of scales. These scales are dark brown, glossy and have a narrow paler margin and fragile edges. Sori are round and indusia absent.Large and Braggins note that ''A. gigantea'' is very similar to ''Alsophila glabra'' and appears to form part of a complex that also includes ''Alsophila podophylla'' and ''Alsophila subdubia''. Further study is needed to determine the nature of the relationship between these taxa.
Naming
The specific epithet ''gigantea'' refers, at least in part, to the large fronds.References:
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