Hybridization and

polyploidy Polyploidy is a condition in which the biological cell, cells of an organism have more than one pair of (Homologous chromosome, homologous) chromosomes. Most species whose cells have Cell nucleus, nuclei (eukaryotes) are diploid, meaning they ha ...

are common phenomena in

ferns 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 except th ...

, and the genus ''

Dryopteris :''The moth genus ''Dryopteris'' is now considered a junior synonym of '' Oreta. ''Dryopteris'' , commonly called the wood ferns, male ferns (referring in particular to ''Dryopteris filix-mas''), or buckler ferns, is a fern genus in the family D ...

'' is known to be one of the most freely-hybridizing fern genera.

North American North America is a continent in the Northern Hemisphere and almost entirely within the Western Hemisphere. It is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South America and the Ca ...

botanists recognized early that there were close relationships between many of the species of ''Dryopteris'' on the continent, and that these relationships reflected hybrid ancestry. The complex includes six sexual

diploid Ploidy () is the number of complete sets of chromosomes in a cell, and hence the number of possible alleles for autosomal and pseudoautosomal genes. Sets of chromosomes refer to the number of maternal and paternal chromosome copies, respectively ...

parents (one of which, "''D. semicristata"'', is hypothesized to be extinct), six sexual allopolyploids, and numerous sterile hybrids at various ploidal levels.

Diploid species

*''

Dryopteris intermedia ''Dryopteris intermedia'', the intermediate wood fern or evergreen wood fern, is a perennial, evergreen wood fern native to eastern North America. It is a diploid species, and is the parent of several species of hybrid origin, including ''Dryopt ...

'' *'' Dryopteris expansa'' *''

Dryopteris goldieana ''Dryopteris goldieana'', commonly called Goldie's wood fern, or giant wood fern is a fern native to the eastern United States and adjacent areas of Canada, from New Brunswick to Ontario and Georgia. It is the largest native North American speci ...

'' *''

Dryopteris ludoviciana ''Dryopteris ludoviciana'', the southern woodfern, is fern native to southern United States from Florida west to Texas and as far north as Kentucky and North Carolina. It is an evergreen in mild climates. Its growth habit is tall and upright wit ...

'' *''

Dryopteris marginalis ''Dryopteris marginalis'', vernacularly known as the marginal shield fern or marginal wood fern, is a perennial species of fern found in damp shady areas throughout eastern North America, from Texas to Minnesota and Newfoundland. It favors moder ...

'' *''Dryopteris "semicristata"''

Allopolyploid species

*''

Dryopteris carthusiana ''Dryopteris carthusiana'' is a species of fern native to damp forests throughout the Holarctic Kingdom. It is known as the narrow buckler-fern in the United Kingdom, and as the spinulose woodfern in North America. It is a tetraploid of hybrid o ...

'' (''D. intermedia'' × ''"D. semicristata"''; allotetraploid) *''

Dryopteris campyloptera ''Dryopteris campyloptera'', also known as the mountain wood fern, is a large American fern of higher elevations and latitudes. It was formerly known as ''Dryopteris spinulosa'' var. ''americana''. This species also has been mistakenly referred ...

'' (''D. intermedia'' × ''D. expansa''; allotetraploid) *''

Dryopteris celsa ''Dryopteris celsa'', the log fern, is a perennial fern in the family Dryopteridaceae. It naturally occurs on rotting logs and the rich soil of swamps and wet woodlands. Its native range includes the southeastern United States. References

...

'' (''D. goldieana'' × ''D. ludoviciana''; allotetraploid) *''

Dryopteris clintoniana ''Dryopteris clintoniana'', commonly known as Clinton's wood fern, is a fern of hybrid origin native to the northern hemisphere. It is a fertile hexaploid, arising as a species by doubling of its chromosome number from a hybrid between ''Dryopte ...

'' (''D. cristata'' × ''D. goldieana''; allohexaploid) *''

Dryopteris cristata ''Dryopteris cristata'' is a species of fern native to wetlands throughout the Northern Hemisphere. It is known as crested wood fern or crested buckler-fern. This plant is a tetraploid species of hybrid origin, one parent being ''Dryopteris ludov ...

'' (''D. ludovicana'' × ''"D. semicristata"''; allotetraploid) *''

Dryopteris filix-mas ''Dryopteris filix-mas'', the male fern, is a common fern of the temperate Northern Hemisphere, native to much of Europe, Asia, and North America. It favours damp shaded areas in the understory of woodlands, but also shady places on hedge-banks, ...

'' (progenitors D. caucasica and D. oreades)

Other hybrids

*''Dryopteris × australis (D. celsa × D. ludoviciana;

triploid Polyploidy is a condition in which the cells of an organism have more than one pair of ( homologous) chromosomes. Most species whose cells have nuclei ( eukaryotes) are diploid, meaning they have two sets of chromosomes, where each set contain ...

)'' *''Dryopteris'' × ''bootii'' (''D. cristata'' × ''D. intermedia'';

) *''Dryopteris'' × ''critica'' (''D. borreri'' × ''D. filix-mas'') *''Dryopteris'' × ''complexa'' aggregate (''D. filix-mas'' and ''D. affinis'';

tetraploid Polyploidy is a condition in which the cells of an organism have more than one pair of ( homologous) chromosomes. Most species whose cells have nuclei (eukaryotes) are diploid, meaning they have two sets of chromosomes, where each set contains ...

) *''Dryopteris'' × ''convoluta'' (''D. cambrensis'' × ''D. filix-mas'') *''Dryopteris'' × ''deweveri'' (''D. dilatata'' × ''D. carthusiana'') *''Dryopteris'' × ''neo-wherryi'' (''D. goldieana'' × ''D. marginalis'';

) *''Dryopteris'' × ''triploidea'' (''D. carthusiana'' × ''D. intermedia''; triploid)

References

{{reflist hybrid Hybrid plants