Regnellidium is a monotypic genus of

fern A fern (Polypodiopsida or Polypodiophyta ) is a member of a group of vascular plants (plants with xylem and phloem) that reproduce via spores and have neither seeds nor flowers. The polypodiophytes include all living pteridophytes exce ...

s of family

Marsileaceae Marsileaceae () is a small family of heterosporous aquatic and semi-aquatic ferns, though at first sight they do not physically resemble other ferns. The group is commonly known as the "pepperwort family" or as the "water-clover family" because ...

. The single living species, ''Regnellidium diphyllum'', the two-leaf water fern, is native to southeastern Brazil and adjacent regions of Argentina. It resembles its relatives from the genus '' Marsilea'', but has 2-lobed leaves (rather than 4). This fern is sometimes grown in aquaria. A fossil assigned to the species ''

Regnellidium upatoiensis Regnellidium is a monotypic genus of ferns of family Marsileaceae. The single living species, ''Regnellidium diphyllum'', the two-leaf water fern, is native to southeastern Brazil and adjacent regions of Argentina. It resembles its relatives fr ...

'' has been found in

Cretaceous The Cretaceous ( ) is a geological period that lasted from about 145 to 66 million years ago (Mya). It is the third and final period of the Mesozoic Era, as well as the longest. At around 79 million years, it is the longest geological period of ...

deposits of the eastern

United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country Continental United States, primarily located in North America. It consists of 50 U.S. state, states, a Washington, D.C., ...

. The genus name of ''Regnellidium'' is in honour of

Anders Fredrik Regnell Anders Fredrik Regnell (8 June 1807 – 12 September 1884) was a Swedish physician and botanist. He studied in Uppsala and received his medical doctorate in 1837. As a student he served as assistant to Anders Retzius in Stockholm. He served in v ...

(1807–1884), a Swedish physician and botanist. It was first described and published in Ark. Bot. Vol.3 (Issue 6) on page 2 in 1904.

References

Other sources

* Mabberley, D. J. (1997). ''The Plant-Book''. Cambridge University Press. Salviniales Flora of Brazil Monotypic fern genera Plants described in 1904 {{Polypodiidae-stub