Parapolystichum is a genus of ferns belonging to the family Dryopteridaceae (the wood fern family), placed in the subfamily Elaphoglossoideae under the Pteridophyte Phylogeny Group classification of 2016 (PPG I). It falls within the order Polypodiales, one of the largest orders of leptosporangiate ferns.
The genus was first described by Keyserling in 1873 as a section of the larger genus Polystichum. It was subsequently elevated to full genus rank by the Chinese botanist R.C. Ching in 1940, in his influential work on the natural classification of the family Polypodiaceae (published in Sunyatsenia, vol. 5). The genus name Parapolystichum reflects its close relationship and morphological similarity to Polystichum.
Parapolystichum ferns are primarily tropical in distribution, with species found across tropical Asia, the Pacific islands, and extending into southeastern Australia. In Australia, the genus is formally recognized under the Australian Plant Census, though in South Australia the species are treated within the broader circumscription of the related genus Lastreopsis.
The genus includes a number of species, among them Parapolystichum acuminatum, Parapolystichum grayi, and Parapolystichum microsorum, all of which are recorded in Australia. As of January 2020, the Checklist of Ferns and Lycophytes of the World served as the primary reference for species circumscription within this genus.
Distribution
Parapolystichum is primarily a tropical genus, with species distributed across tropical regions of Asia and the Pacific. Its range extends southward into southeastern Australia, where several species are recognized under the Australian Plant Census.
Taxonomy Notes
Parapolystichum was originally circumscribed by Keyserling in 1873 as a section of Polystichum, and raised to generic rank by R.C. Ching in 1940. Under the 2016 PPG I classification, it is placed in subfamily Elaphoglossoideae of the family Dryopteridaceae. In South Australia, the genus is included within the broader circumscription of Lastreopsis by the Australian Plant Census.
