Gymnosphaera glabra
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Gymnosphaera glabra, synonyms Alsophila glabra and Cyathea glabra,[1] is a species of tree fern native to Borneo, western Java, Sumatra, the Lesser Sunda Islands, Sulawesi, and the Malay Peninsula,[2] where it grows in lowland swamp forest and montane forest at an elevation of up to 1500 m. The trunk of this plant is erect and 2–4 m tall. Fronds are bi- or tripinnate and 1–2 m in length. Characteristically of this species, the lowest pinnae may be significantly reduced. The stipe is very dark and bears basal scales. These scales are dark, glossy and have a paler margin and fragile edges. Sori are produced in groups of one to three on fertile pinnule veins. They lack indusia.[3]
Large and Braggins (2004) noted that G. glabra is very similar to Gymnosphaera gigantea and appears to form part of a complex that also includes G. podophylla and G. subdubia. Further study is needed to determine the nature of the relationship between these taxa.[3]