The Cyatheaceae are a

family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...

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

record in the

late Jurassic The Late Jurassic is the third Epoch (geology), epoch of the Jurassic Period, and it spans the geologic time scale, geologic time from 161.5 ± 1.0 to 143.1 ± 0.8 million years ago (Ma), which is preserved in Upper Jurassic stratum, strata.Owen ...

, though the modern

genera Genus (; : genera ) is a taxonomic rank above species and below family as used in the biological classification of living and fossil organisms as well as viruses. In binomial nomenclature, the genus name forms the first part of the binomial s ...

likely appeared in the

Cenozoic The Cenozoic Era ( ; ) is Earth's current geological era, representing the last 66million years of Earth's history. It is characterized by the dominance of mammals, insects, birds and angiosperms (flowering plants). It is the latest of three g ...

. Cyatheaceae are the largest family of tree ferns, including about 640 species. Cyatheaceae and Dicksoniaceae, together with Metaxyaceae and Cibotiaceae, 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 most familiar group of monilophytes. The Cyatheaceae usually have a single, erect or creeping

rhizome In botany and dendrology, a rhizome ( ) is a modified subterranean plant stem that sends out roots and Shoot (botany), shoots from its Node (botany), nodes. Rhizomes are also called creeping rootstalks or just rootstalks. Rhizomes develop from ...

(stem). Their fronds (leaves) are also very large, although not as large as the tree ferns of the Marattiaceae. 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 ...

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 An epiphyte is a plant or plant-like organism that grows on the surface of another plant and derives its moisture and nutrients from the air, rain, water (in marine environments) or from debris accumulating around it. The plants on which epiphyt ...

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 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 ...

and

spores In biology, a spore is a unit of sexual (in fungi) 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 plant ...

.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

clade In biology, a clade (), also known as a Monophyly, monophyletic group or natural group, is a group of organisms that is composed of a common ancestor and all of its descendants. Clades are the fundamental unit of cladistics, a modern approach t ...

s 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 were used to organize the Cyatheaceae into

taxonomic rank In biology, taxonomic rank (which some authors prefer to call nomenclatural rank because ranking is part of nomenclature rather than taxonomy proper, according to some definitions of these terms) is the relative or absolute level of a group of or ...

s. Most recently,

plastid A plastid is a membrane-bound organelle found in the Cell (biology), cells of plants, algae, and some other eukaryotic organisms. Plastids are considered to be intracellular endosymbiotic cyanobacteria. Examples of plastids include chloroplasts ...

DNA Deoxyribonucleic acid (; DNA) is a polymer composed of two polynucleotide chains that coil around each other to form a double helix. The polymer carries genetic instructions for the development, functioning, growth and reproduction of al ...

has been used, suggesting the Cyatheaceae should be split into four

s: ''

Sphaeropteris ''Sphaeropteris'' is a genus of tree ferns in the family Cyatheaceae. It has been treated as a subgenus within the genus ''Cyathea'', but is accepted in the Pteridophyte Phylogeny Group classification of 2016 (PPG I). Description Species of ' ...

'', '' Cyathea'', '' 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 *'' Cyathea'' Sm., about 265 species *''

'' 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/ {{Authority control Fern families