''Plenasium angustifolium'' is a fern in the

family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...

Osmundaceae Osmundaceae (royal fern family) is a family of ferns containing four to six extant genera and 18–25 known species. It is the only living family of the order Osmundales in the class Polypodiopsida (ferns) or in some classifications the only ord ...

. The genus ''

Plenasium ''Plenasium'' is a genus of ferns in the family Osmundaceae. It is recognized in the Pteridophyte Phylogeny Group The Pteridophyte Phylogeny Group (PPG) is an informal international group of systematic botanists who collaborate to establish on ...

'' is recognized in the

Pteridophyte Phylogeny Group The Pteridophyte Phylogeny Group (PPG) is an informal international group of systematic botanists who collaborate to establish on the classification of pteridophytes ( lycophytes and ferns) that reflects knowledge about plant relationships discove ...

classification of 2016 (PPG I); however, some sources place all ''Plenasium'' species in a more broadly defined ''

Osmunda ''Osmunda'' is a genus of primarily temperate-zone ferns of family Osmundaceae. Five to ten species have been listed for this genus. They have existed since the Early Cretaceous. Description Completely dimorphic fronds or pinnae (hemidimorphic ...

'', treating this species as ''Osmunda angustifolia''. It is native to eastern Thailand, Laos and southern China (Hainan, Guangdong, Hong Kong, Hunan), and has been introduced into India and Sri Lanka.

References

Osmundales Flora of China Flora of Laos Flora of Thailand Plants described in 1959 {{Polypodiidae-stub