The

fern The ferns (Polypodiopsida or Polypodiophyta) are a group of vascular plants (plants with xylem and phloem) that reproduce via spores and have neither seeds nor flowers. They differ from mosses by being vascular, i.e., having specialized tissue ...

genus ''Todea'' is known from only two living species. Species in the genus ''Todea'', as '' Leptopteris'', are distinct from other in Osmundaceae in that

sporangia A sporangium (from Late Latin, ; : sporangia) is an enclosure in which spores are formed. It can be composed of a unicellular organism, single cell or can be multicellular organism, multicellular. Virtually all plants, fungus, fungi, and many ot ...

are born on laminar pinnules.

Description

The species in the genus have a sub-erect stem and coarse,

pinnate Pinnation (also called pennation) is the arrangement of feather-like or multi-divided features arising from both sides of a common axis. Pinnation occurs in biological morphology, in crystals, such as some forms of ice or metal crystals, and ...

leaves. Many large sporangia are located on the bottoms of the leaves and are not arranged in sori or covered by an

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

Species

Only two extant species are currently recognised. '' Todea barbara'' L., known as the king fern, is native to

South Africa South Africa, officially the Republic of South Africa (RSA), is the Southern Africa, southernmost country in Africa. Its Provinces of South Africa, nine provinces are bounded to the south by of coastline that stretches along the Atlantic O ...

New Zealand New Zealand () is an island country in the southwestern Pacific Ocean. It consists of two main landmasses—the North Island () and the South Island ()—and List of islands of New Zealand, over 600 smaller islands. It is the List of isla ...

, and

Australia Australia, officially the Commonwealth of Australia, is a country comprising mainland Australia, the mainland of the Australia (continent), Australian continent, the island of Tasmania and list of islands of Australia, numerous smaller isl ...

while '' Todea papuana'' H. is known only from

Papua New Guinea Papua New Guinea, officially the Independent State of Papua New Guinea, is an island country in Oceania that comprises the eastern half of the island of New Guinea and offshore islands in Melanesia, a region of the southwestern Pacific Ocean n ...

. So far the fossil record of the genus ''Todea'' consists only of the permineralized rhizome '' Todea tidwellii'' from the Lower

Cretaceous The Cretaceous ( ) is a geological period that lasted from about 143.1 to 66 mya (unit), million years ago (Mya). It is the third and final period of the Mesozoic Era (geology), Era, as well as the longest. At around 77.1 million years, it is the ...

Vancouver Island Vancouver Island is an island in the northeastern Pacific Ocean and part of the Canadian province of British Columbia. The island is in length, in width at its widest point, and in total area, while are of land. The island is the largest ...

, Canada and the species ''Todea amissa'', known from the Eocene of

Patagonia Patagonia () is a geographical region that includes parts of Argentina and Chile at the southern end of South America. The region includes the southern section of the Andes mountain chain with lakes, fjords, temperate rainforests, and glaciers ...

Argentina Argentina, officially the Argentine Republic, is a country in the southern half of South America. It covers an area of , making it the List of South American countries by area, second-largest country in South America after Brazil, the fourt ...

. ''Todea minutacaulis'' has also been described from the Lower Cretaceous of Vancouver Island and represents the first anatomically preserved fossil fern sporeling from the fossil record.

References

Bibliography

* Nathan Jud, Gar W.Rothwell and Ruth A. Stockey. 2008. "''Todea'' from the Lower Cretaceous of western North America: implications for the phylogeny, systematics, and evolution of modern Osmundaceae." American Journal of Botany, 95:330-339. * E.Hennipman. 1968. A new ''Todea'' from New Guinea, with remarks on the generic delimitation of recent Osmundaceae. Blumea 16: 105-108 * C.Michael Hogan. 2010
''Fern''. Encyclopedia of Earth. eds. Saikat Basu and C.Cleveland. National Council for Science and the Environment
Washington DC. * Walker, Z., Rothwell, G. W., & Stockey, R. A. 2023
Fossil evidence for sporeling development of a Mesozoic osmundaceous fern
''American Journal of Botany'', 110: e16210-n/a. https://doi.org/10.1002/ajb2.16210

External links

- ''includes photos'' (author: David Nicholls, January 1998). Osmundales Ferns of Australasia Fern genera {{Polypodiidae-stub