''Diplazium'' is a genus of ferns that specifically includes the approximately 400 known species of twinsorus ferns. The Greek root is ''diplazein'' meaning ''double'': the indusia in this genus lie on both sides of the vein. These ferns were earlier considered part of either the Athyriaceae, Dryopteridaceae, Aspleniaceae, or Polypodiaceae families or recognized as belonging to their own taxonomic family. The

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

classification of 2016 (PPG I) places the genus in the

Athyriaceae The Athyriaceae (ladyferns and allies) are a family of terrestrial ferns in the order Polypodiales. In the Pteridophyte Phylogeny Group classification of 2016 (PPG I), the family is placed in the suborder Aspleniineae, and includes two gene ...

. The taxonomy of the genus is difficult and poorly known, and by 2009 has never been the subject of a complete monographic study. Their distribution is pantropical, with a few species extending into temperate areas. The

rhizome In botany and dendrology, a rhizome (; , ) is a modified subterranean plant stem that sends out roots and shoots from its nodes. Rhizomes are also called creeping rootstalks or just rootstalks. Rhizomes develop from axillary buds and grow hori ...

of the genus ''Diplazium'' varies from creeping to erect, and is scaly. Its fronds are deciduous or evergreen, are trophopodicThe trophopod is food storage organ described from a number of North American ferns. It consists of the enlarged and modified leaf base filled with starch storage tissue. See W. H. Wagner, Jr. and D. M. Johnson, ''Taxon'', Vol. 32, No. 2 (May, 1983), pp. 268-269 for more information on this organ. and are either

monomorphic Monomorphic or Monomorphism may refer to: *Monomorphism, an injective homomorphism in mathematics * Monomorphic QRS complex, a wave pattern seen on an electrocardiogram * Monomorphic, a linguistic term meaning "consisting of only one morpheme" *Mo ...

or weakly dimorphic. The stipe is green, deeply grooved from above, and is either scaly or glabrous. It always has two lunate vascular bundles. The blades are either singular or in sets of two and are entirely pinnate, range from oblong-lanceolate to deltate, and from

herbaceous Herbaceous plants are vascular plants that have no persistent woody stems above ground. This broad category of plants includes many perennials, and nearly all annuals and biennials. Definitions of "herb" and "herbaceous" The fourth edition of t ...

to papery. It has linear basal sori that are paired back-to-back on the same vein. The

indusium A sorus (pl. sori) is a cluster of sporangia (structures producing and containing spores) in ferns and fungi. A coenosorus (plural coenosori) is a compound sorus composed of multiple, fused sori. Etymology This New Latin word is from Ancient ...

is linear and persistent, and the sporangia are brownish. Some common species include ''Diplazium hymenodes'', the peacock fern; ''Diplazium esculentum'', the vegetable fern; ''Diplazium molokaiense'', the Molokai twinsorus fern; and ''Diplazium lonchophyllum'', the lance-leaved glade fern.

Taxonomy

''Diplazium'' is in the family

in the eupolypods II clade of the order Polypodiales. The common glade fern of North America, ''Diplazium pycnocarpon'', is found not to belong to that genus, but rather placed in the genus ''

Homalosorus ''Homalosorus'' is a genus of fern with only one species, ''Homalosorus pycnocarpos''. It may also be referred to by its older synonyms ''Athyrium pycnocarpon'' and ''Diplazium pycnocarpon''. Commonly referred to as the narrow-leaved glade fern, ...

'' (

Diplaziopsidaceae Diplaziopsidaceae is a family of ferns in the order Polypodiales. In the Pteridophyte Phylogeny Group classification of 2016 (PPG I), the family is placed in the suborder Aspleniineae, and includes two genera. Alternatively, it may be treat ...

). Two further species formerly placed in the genus have been transferred to a new genus, ''

Desmophlebium ''Desmophlebium'' is a genus of ferns. In the Pteridophyte Phylogeny Group classification of 2016, it is the only genus in the family Desmophlebiaceae. Other sources place it in a more widely defined Aspleniaceae. Taxonomy The family and genus w ...

''.

Selected species

*''

Diplazium australe ''Diplazium australe'', commonly known as the Austral lady fern, is a small fern occurring in eastern Australia, New Zealand New Zealand ( mi, Aotearoa ) is an island country in the southwestern Pacific Ocean. It consists of two main ...

'' *''

Diplazium dietrichianum ''Diplazium dietrichianum'' is a small fern occurring in eastern Australia. It occurs in shady damp places.sign at the Royal Botanic Gardens, Sydney The Royal Botanic Garden, Sydney is a heritage-listed major botanical garden, event venue ...

'' *''

Diplazium esculentum ''Diplazium esculentum'', the vegetable fern, is an edible fern found throughout Asia and Oceania. It is probably the most commonly consumed fern. The genus ''Diplazium'' is in the family Athyriaceae, in the eupolypods II clade of the order Pol ...

'' *''

Diplazium fraxinifolium ''Diplazium fraxinifolium'' is a species of fern in the family Athyriaceae. It is found from India through Malesia to New Guinea New Guinea (; Hiri Motu: ''Niu Gini''; id, Papua, or , historically ) is the world's second-largest island ...

'' *''

Diplazium melanochlamys ''Diplazium melanochlamys'' is a ground fern only found on Lord Howe Island in the relatively remote Pacific Ocean between Australia and New Zealand. A common plant growing in forest. Most often seen on the southern half of the island. It can be ...

'' *''

Diplazium molokaiense ''Diplazium molokaiense'' is a rare species of fern known by the common name Molokai twinsorus fern. It is endemic to Hawaii, where it is one of the rarest ferns.Wood, K. R. (2006)Conservation status of the Hawaiian endemic fern ''Diplazium molok ...

'' *''

Diplazium sibiricum ''Diplazium sibiricum'', otherwise known as the Mole-Ladder is a species of fern. It is found in Siberia, across Russia, in Finland Finland ( fi, Suomi ; sv, Finland ), officially the Republic of Finland (; ), is a Nordic country in ...

Notes

References

{{Taxonbar, from=Q1802740 Athyriaceae Fern genera Pantropical flora Taxa named by Olof Swartz