''Osmunda'' is a genus of primarily temperate-zone ferns of family Osmundaceae. Five to ten species have been listed for this genus.

Description

Completely dimorphic fronds or pinnae (hemidimorphic), green

photosynthetic Photosynthesis is a process used by plants and other organisms to convert light energy into chemical energy that, through cellular respiration, can later be released to fuel the organism's activities. Some of this chemical energy is stored in c ...

sterile fronds, and non-photosynthetic

spore In biology, a spore is a unit of sexual or asexual reproduction that may be adapted for dispersal and for survival, often for extended periods of time, in unfavourable conditions. Spores form part of the life cycles of many plants, algae, f ...

-bearing fertile pinnae, with large, naked sporangia. Because of the large mass of sporangia that ripen uniformly at the same time to a showy golden color, the ferns look as if they are in flower, and so this genus is sometimes called the "flowering ferns".

Taxonomy

''Osmunda'', the type genus of the fern

order Order, ORDER or Orders may refer to: * Categorization, the process in which ideas and objects are recognized, differentiated, and understood * Heterarchy, a system of organization wherein the elements have the potential to be ranked a number of d ...

, Osmundales has historically been the largest genus in the family Osmundaceae. Smith et al. (2006), who carried out the first higher-level

pteridophyte A pteridophyte is a vascular plant (with xylem and phloem) that disperses spores. Because pteridophytes produce neither flowers nor seeds, they are sometimes referred to as "cryptogams", meaning that their means of reproduction is hidden. Ferns, ...

classification published in the

molecular phylogenetic Molecular phylogenetics () is the branch of phylogeny that analyzes genetic, hereditary molecular differences, predominantly in DNA sequences, to gain information on an organism's evolutionary relationships. From these analyses, it is possible to ...

era, described three genera in that family, namely ''Osmunda'', '' Leptopteris'', and '' Todea''. The genus has also been treated historically as consisting of a number of subgroups, generally subgenera, ''Osmunda'' (3 species), ''Osmundastrum'' (2 species), and ''Plenasium'' (3–4 species). However, there was suspicion that the genus was not

monophyletic In cladistics for a group of organisms, monophyly is the condition of being a clade—that is, a group of taxa composed only of a common ancestor (or more precisely an ancestral population) and all of its lineal descendants. Monophyletic gro ...

. The publication of a detailed phylogeny of the family by Metzgar et al. in 2008 showed that ''Osmunda'' as

circumscribed In geometry, the circumscribed circle or circumcircle of a polygon is a circle that passes through all the vertices of the polygon. The center of this circle is called the circumcenter and its radius is called the circumradius. Not every po ...

was

paraphyletic In taxonomy (general), taxonomy, a group is paraphyletic if it consists of the group's most recent common ancestor, last common ancestor and most of its descendants, excluding a few Monophyly, monophyletic subgroups. The group is said to be pa ...

and that '' Osmunda cinnamomea'', despite its morphological similarity to '' Osmunda claytoniana'', was sister to the rest of the family, and resurrected the segregate genus ''Osmundastrum'', by elevating it from subgenus, to contain it and render ''Osmunda''

. The phylogeny of ''Osmunda'' is shown in the following cladograms. A number of authors have proposed elevating the subgenera to separate genus level, In 2016 the Pteridophyte Phylogeny Group (PPG) classification split ''Osmunda'' further by elevating its subgenera to genera as ''Claytosmunda'' and ''Plenasium'', leaving only the species originally included in subgenus ''Osmunda''. *'' O. abyssinica'' (Kuhn 1879) Bobrov *'' O. acuta'' (Burm.fil. 1768) Fraser-Jenk. *'' O. chengii'' Bomfleur, Grimm & McLoughlin 'Osmunda claytoniites'' Phipps, Taylor & Taylor non Graham 1963">Osmunda_claytoniites.html" ;"title="'Osmunda claytoniites">'Osmunda claytoniites'' Phipps, Taylor & Taylor non Graham 1963ref>Thomas N. Taylor, Edith L. Taylor, Michael Krings: Paleobotany. The Biology and Evolution of Fossil Plants . Second Edition, Academic Press 2009, , p. 437-443 *'' O. herbacea'' Copeland *'' O. hybrida'' Tsutsumi et al. *'' O. × intermedia'' *'' O. japonica'' Thunberg (Japanese flowering fern) *'' O. lancea'' Thunberg (Japanese lancea flowering fern) *'' O. x mildei'' *'' O. piresii'' Brade 1965 *'' O. regalis'' L. (Old World royal fern) *'' O. × ruggii'' *''Osmunda spectabilis">O. spectabilis'' Willdenow (American royal fern) *''Osmunda wehrii">O. wehrii'' Miller (Middle Miocene, Washington state)

Etymology

The derivation of the genus name is uncertain. A leading theory is that it is from an English folk tale of a boatman named Osmund hiding his wife and children in a patch of royal fern during the Danish invasion. Other theories propose that it is from Middle English and Middle French words for a type of fern.

Ecology

''Osmunda'' species are used as food plants by the larvae of some

Lepidoptera Lepidoptera ( ) is an order (biology), order of insects that includes butterfly, butterflies and moths (both are called lepidopterans). About 180,000 species of the Lepidoptera are described, in 126 Family (biology), families and 46 Taxonomic r ...

species including the engrailed. One of the species, the cinnamon fern (''Osmundastrum cinnamomeum'') forms huge clonal colonies in

swamp A swamp is a forested wetland.Keddy, P.A. 2010. Wetland Ecology: Principles and Conservation (2nd edition). Cambridge University Press, Cambridge, UK. 497 p. Swamps are considered to be transition zones because both land and water play a role in ...

areas. These ferns form massive rootstocks with densely matted, wiry roots. This root mass is an excellent substrate for many epiphytal plants. They are often harvested as osmundine and used horticulturally, especially in propagating and growing orchids.

References

Bibliography

* * * * * * * * * * * * , in * Phipps, C.J., Taylor, T.N., Taylor, E.L., Cuneo, N.R., Boucher, L.D., and Yao, X. (1998). ''Osmunda'' (Osmundaceae) from the Triassic of Antarctica: An example of evolutionary stasis. American Journal of Botany 85: 888-895

External links

Germplasm Resources Information Network: ''Osmunda''Flora of North America: ''Osmunda''
*http://data.gbif.org/species/browse/taxon/13191108 {{Taxonbar, from=Q1427328 Osmundales Extant Triassic first appearances Fern genera Taxa named by Carl Linnaeus