Classification
 Subordinate Taxa
 Nomenclature
Scientific Name:
Dicranopteris Bernh., Neues J. Bot. 1(2): 38 (1805)
Synonymy:
  • = Mertensia Willd., Kongl. Vetensk. Acad. Nya Handl. 25: 165 (1804) nom. illeg., non Mertensia Roth 1797
Type Taxon:
Dicranopteris dichotoma (Thunb.) Bernh. = Dicranopteris linearis (Burm.f.) Underw.
Etymology:
From the Greek dikranos (two-branched), and pteris (a fern), a reference to the dichotomous branching pattern.
 Description

Terrestrial ferns. Rhizomes long-creeping, hairy. Stipes hairy or glabrescent. Rachis reduced to a bud at the apex of the stipe with a single pair of pinnae; rachis buds sometimes extending to produce another tier comprising a rachis terminating in another rachis bud and pair of pinnae. Pinnae unforked, being equivalent to a single ultimate leaflet (rarely NZ), or forking pseudodichotomously 1–2 times; buds at bifurcations sometimes extending once. Laminae, axes, and rachis and pinna buds hairy, these hairs sometimes branched, scales absent. β costae lacking costal segments. α costae of the ultimate leaflets arising pseudodichotomously from distal end of β costae. Ultimate segments on α costa >10 mm long, oblong, entire, with veins branching two or more times between midvein and margin. Sori superficial, 6–20 either side of midvein, each with 7–12 sporangia. Spores trilete, radially symmetrical, plain or shallowly rugulate.

 Taxonomy

A genus of 10–20 species. Species limits are poorly defined, with the widespread Dicranopteris linearis particularly problematic.

Allan (1961) included Dicranopteris in a broadly-circumscribed Gleichenia. The nomenclatural history of Dicranopteris was detailed by Pichi Sermolli (1972). Dicranopteris Bernh. is a replacement name for Mertensia Willd., a later homonym of Mertensia Roth (Boraginaceae). Bernhardi (1805) lectotypified Mertensia Willd. (and Dicranopteris by extension) by including in his new genus only one of the species from Willdenow’s genus, M. dichotoma (Thunb.) Willd. (≡ Polypodium dichotomum Thunb. ≡ D. dichotoma (Thunb.) Bernh.).

 Recognition

Dicranopteris can be distinguished from the superficially-similar Sticherus by the absence of lamina on the axes subtending the pseudodichotomously-paired ultimate leaflets; that is, Dicranopteris has no costal segments on the β costae, whereas Sticherus does. The ultimate segments of Dicranopteris are at least 11 mm in length, in contrast to Gleichenia, which has ultimate segments less than 3 mm long. In New Zealand, Dicranopteris is only found in geothermal areas of the central North Island.

 Distribution

Ten to twenty species distributed throughout the tropics and subtropics, extending to southern temperate Australia and New Zealand; about three to five species in each of America (Mickel & Smith 2004), Africa and neighbouring islands (Roux 2009), India (Fraser-Jenkins 2009), China and Japan (Xiaofeng et al. 2013), Malesia (Holttum 1959), and the Pacific (Minagawa & Kuratsuji 2008), with one in Australia (Chinnock & Bell 1998). One non-endemic species in New Zealand.

 Biostatus
Indigenous (Non-endemic)
Number of species in New Zealand within Dicranopteris Bernh.
CategoryNumber
Indigenous (Non-endemic)1
Total1
 Cytology

The base chromosome number in Dicranopteris is x = 39 (Kramer 1990).

 Notes

Holttum (1957, p.170) pointed out that the hairs of Dicranopteris are often branched, particularly at the base, which may be "rather massive, not hair like". Nevertheless, the ‘hairs’ of Dicranopteris are markedly different from the scales and other indumentum found in Gleichenia and Sticherus, and this terminological convention is widely followed.

 Bibliography
Bernhardi, J.J. 1805: Dritter Versuch einer Anordnung der Farrnkräuter. Neues Journal für die Botanik 1(2): 1–50.
Chinnock, R.J.; Bell, G.H. 1998: Gleicheniaceae. In: Flora of Australia. Vol. 48. 148–162.
Fraser-Jenkins, C.R. 2009: A brief comparison of modern pteridophyte classifications (families and genera in India). Indian Fern Journal 26: 107–126.
Holttum, R.E. 1957: Morphology, growth-habit, and classification in the family Gleicheniaceae. Phytomorphology 7: 168–184.
Holttum, R.E. 1959: Gleicheniaceae. In: Flora Malesiana, Series II - Pteridophyta. Vol. 1. 1–36.
Jin, X.; Ding, B.; Iwatsuki, K. 2013: Gleicheniaceae. In: Zhengyi, W.; Raven, P.H.; Deyuan, H. (ed.) Flora of China. Lycopodiaceae through Polypodiaceae. Vol. 2–3. Science Press, Beijing.
Kramer, K.U. 1990: Gleicheniaceae. In: Kramer, K.U.; Green, P.S. Pteridophytes and gymnosperms. Vol. 1. In: Kubitzki, K. (ed.) The Families and Genera of Vascular Plants. Springer-Verlag, Berlin.
Kramer, K.U.; Green, P.S. 1990: Pteridophytes and gymnosperms. Kubitzki, K. (ed.) The Families and Genera of Vascular Plants. Vol. 1. Springer-Verlag, Berlin.
Mickel, J.T.; Smith, A.R. 2004: The Pteridophytes of Mexico. Memoirs of the New York Botanical Garden 88: 1–1054.
Minagawa, R.; Kuratsuji, R. 2008: Gleicheniaceae. In: Nakamura, M. (ed.) Illustrated flora of ferns and fern allies of South Pacific Islands. In: National Museum of Nature and Science Book Series No. 8. Tokai University Press, Tokyo.
Perrie, L.R.; Brownsey, P.J. 2015: Gleicheniaceae. In: Breitwieser, I; Heenan, P.B.; Wilton, A.D. (ed.) Flora of New Zealand — Ferns and Lycophytes. Fascicle 12. Manaaki Whenua Press, Lincoln.
Pichi Sermolli, R.E.G. 1972: Names and types of fern genera. 3 – Ophioglossaceae, Osmundaceae, Stromatopteridaceae, Gleicheniaceae, Dipteridaceae, Plagiogyriaceae. Webbia 26: 491–536.
Roux, J.P. 2009: Synopsis of the Lycopodiophyta and Pteridophyta of Africa, Madagascar and neighbouring islands. Strelitzia 23: 1–296.
Willdenow, C.L. 1804: Mertensia, ett nytt slägte af Ormbunkarne. Kongliga Vetenskaps Academiens Nya Handlingar 25: 163–170.