The Cyatheaceae are a

family Family (from la, familia) is a group of people related either by consanguinity (by recognized birth) or affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its members and of society. Idea ...

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 ...

, the scaly tree ferns, one of eight families in the order Cyatheales in the Pteridophyte Phylogeny Group classification of 2016 (PPG I). Alternatively, the family may defined much more broadly (Cyatheaceae ''

sensu lato ''Sensu'' is a Latin word meaning "in the sense of". It is used in a number of fields including biology, geology, linguistics, semiotics, and law. Commonly it refers to how strictly or loosely an expression is used in describing any particular c ...

'') as the only family in the Cyatheales, with the PPG I family treated as the subfamily Cyatheoideae. The narrower

circumscription Circumscription may refer to: *Circumscribed circle * Circumscription (logic) *Circumscription (taxonomy) *Circumscription theory, a theory about the origins of the political state in the history of human evolution proposed by the American anthrop ...

is used in this article. The family includes the world's tallest tree ferns, which reach heights up to 20 m. They are also very ancient plants, appearing in the

fossil A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved ...

record in the

late Jurassic The Late Jurassic is the third epoch of the Jurassic Period, and it spans the geologic time from 163.5 ± 1.0 to 145.0 ± 0.8 million years ago (Ma), which is preserved in Upper Jurassic strata.Owen 1987. In European lithostratigraphy, the name ...

, though the modern genera likely appeared in the Cenozoic. Cyatheaceae are the largest family of tree ferns, including about 640 species. Cyatheaceae and

Dicksoniaceae Dicksoniaceae is a group of tropical, subtropical and warm temperate ferns, treated as a family in the Pteridophyte Phylogeny Group classification of 2016 (PPG I), and counting 30-40 species. Alternatively, the family may be sunk into a very bro ...

, together with Metaxyaceae and

Cibotiaceae ''Cibotium'' (from Ancient Greek language, Greek , ''kibṓtion'', "little chest" or "box"), also known as manfern, is a genus of 11 species of tropical Cyatheales, tree ferns. It is the only genus in family Cibotiaceae in the Pteridophyte Phylog ...

, do not form a strongly supported monophyletic group and could be paraphyletic, but several individual subgroups are well supported as being monophyletic. Cyatheaceae are

leptosporangiate ferns The Polypodiidae, commonly called leptosporangiate ferns, formerly Leptosporangiatae, are one of four subclasses of ferns, and the largest of these, being the largest group of living ferns, including some 11,000 species worldwide. The group has ...

, the most familiar group of

monilophyte 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 ...

s. The Cyatheaceae usually have a single, erect or creeping rhizome (stem). Their fronds (leaves) are also very large, although not as large as the tree ferns of the

Marattiaceae Marattiaceae is the only family of extant (living) ferns in the order Marattiales. In the Pteridophyte Phylogeny Group classification of 2016 (PPG I), Marattiales is the only order in the subclass Marattiidae. The family has six genera and about ...

. Some species have fronds reaching 3–4 m in length, and have a final crown width of some 6 m. The fronds are circinate before unfolding and usually

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 in ...

ly or bipinnately compound, with deeply pinnately lobed leaflets. The large leaves are covered in scales and hairs, and bear sori (spore clusters) on their undersides.Judd, W.S., C.S. Campbell, E.A. Kellogg, P.F. Stevens, and M.J. Donoghue (Eds.) 2008. Plant Systematics: A Phylogenetic Approach, Third Edition. Sinauer Associates, Sunderland, Massachusetts, USA. The sori are often covered by a flap of tissue called an indusium, a useful characteristic for classifying the Cyatheaceae. Some indusia are cup-shaped (cyatheoid), while others are hood-shaped (hemitelioid), enclose the sorus (sphaeropteroid), or scaly. Like most ferns, members of the Cyatheaceae are homosporous. Cyatheaceae are found in both New and Old World tropical wet montane forests and cloud forests, with some species extending into south-temperate regions. Most Cyatheaceae are terrestrial, with one being a facultative epiphyte and others having a creeping habit. Long Bao Valley Cyatheaceae

Cyatheaceae can be distinguished from arborescent '' Dicksonia'' by the presence of scales, the position of the sori, and the morphology of sporangia and

spores 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, ...

.Holttum, R.E. and P.J. Edwards. 1983. The tree-ferns of Mount Roraima and neighbouring areas of the Guayana highlands with comments on the family Cyatheaceae. Kew Bulletin 38(2): 155-188. In the Cyatheaceae, the sori occur away from the margins of the pinnules, and are elongate or rounded.

Taxonomy

, two different circumscriptions of the family Cyatheaceae are used, as summarized in the table below. In the Pteridophyte Phylogeny Group classification of 2016 (PPG I), the family is one of eight in the order Cyatheales, and has three genera. In the classification of Christenhusz & Chase (2014), the family is the only one in the order Cytheales, the families of PPG I being reduced to subfamilies. It then has 13–14 genera. The '' sensu stricto'' circumscription of PPG I is used here.

Genera

Since the exact number of species is not known, classification of the Cyatheaceae ''s.s.'' has had a long and controversial history, and is still undergoing revision. Three tentative clades have been developed: ''Alsophila'', ''Cyathea'', and ''Sphaeropteris''. These are frequently used as genus names. ''Cnemidaria'', ''Trichopteris'' (or ''Trichipteris''), and ''Nephelea'' (or ''Nephelia'') have also been suggested as genera. Initially, indusium and scale

morphology Morphology, from the Greek and meaning "study of shape", may refer to: Disciplines * Morphology (archaeology), study of the shapes or forms of artifacts * Morphology (astronomy), study of the shape of astronomical objects such as nebulae, galaxies ...

were used to organize the Cyatheaceae into

taxonomic rank In biological classification, taxonomic rank is the relative level of a group of organisms (a taxon) in an ancestral or hereditary hierarchy. A common system consists of species, genus, family, order, class, phylum, kingdom, domain. While ...

s. Most recently, plastid DNA has been used, suggesting the Cyatheaceae should be split into four clades: '' Sphaeropteris'', ''

Cyathea ''Cyathea'' is a genus of tree ferns, the type genus of the fern order Cyatheales. The genus name ''Cyathea'' is derived from the Greek ''kyatheion'', meaning "little cup", and refers to the cup-shaped sori on the underside of the fronds. De ...

'', '' Alsophila'', and ''Gymnosphaera + A. capensis''. , it remained unclear which of these groups should be considered genera and which subgenera. The Pteridophyte Phylogeny Group classification of 2016 (PPG I) accepts three genera, placing the ''Gymnosphaera'' clade within ''Alsophila'': *'' Alsophila'' R.Br., about 275 species *''

'' Sm., about 265 species *'' Sphaeropteris'' Bernh., about 103 species

References

* Large, M.F. and J.E. Braggins ''Tree Ferns''. Timber Press (2004).

External links

Tree ferns:Monophyletic groups and their relationships as revealed by four protein-coding plastid loci
* Palacios-Rios, M. 2007. https://web.archive.org/web/20170107191324/http://www.helechos.com.mx/ {{Taxonbar, from=Q133312 Fern families