The Cyatheaceae are a

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

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 The order Cyatheales, which includes most tree ferns, is a taxonomic order of the fern class, Polypodiopsida. No clear morphological features characterize all of the Cyatheales, but DNA sequence data indicate the order is monophyletic. Some sp ...

in the

Pteridophyte Phylogeny Group The Pteridophyte Phylogeny Group, or PPG, is an informal international group of systematic botanists who collaborate to establish a consensus on the classification of pteridophytes ( lycophytes and ferns) that reflects knowledge about plant relatio ...

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 co ...

'') 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 Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nomenclat ...

likely appeared in the

Cenozoic The Cenozoic ( ; ) is Earth's current geological era, representing the last 66million years of Earth's history. It is characterised by the dominance of mammals, birds and flowering plants, a cooling and drying climate, and the current configura ...

. 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 ''Metaxya'' is a neotropical genus of ferns in the order Cyatheales. It is the only genus in the family Metaxyaceae in the Pteridophyte Phylogeny Group classification of 2016 (PPG I). Alternatively, the genus may be placed in the subfamily Metax ...

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

(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 In mathematics, an annulus (plural annuli or annuluses) is the region between two concentric circles. Informally, it is shaped like a ring or a hardware washer. The word "annulus" is borrowed from the Latin word ''anulus'' or ''annulus'' mean ...

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 An epiphyte is an organism that grows on the surface of a 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 epiphytes grow are called phoroph ...

and others having a creeping habit. Long Bao Valley Cyatheaceae

Cyatheaceae can be distinguished from arborescent ''

Dicksonia ''Dicksonia'' is a genus of tree ferns in the order Cyatheales. It is regarded as related to ''Cyathea'', but is considered to retain more primitive traits, dating back at least to the Jurassic and Cretaceous periods. The fossil record includes ...

'' by the presence of scales, the position of the sori, and the morphology of

sporangia A sporangium (; from Late Latin, ) is an enclosure in which spores are formed. It can be composed of a single cell or can be multicellular. Virtually all plants, fungi, and many other lineages form sporangia at some point in their life cyc ...

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, f ...

.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

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 ''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 co ...

'' 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 A clade (), also known as a monophyletic group or natural group, is a group of organisms that are monophyletic – that is, composed of a common ancestor and all its lineal descendants – on a phylogenetic tree. Rather than the English term, ...

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 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 (biology), family, order (biology), order, class (b ...

s. Most recently,

plastid The plastid (Greek: πλαστός; plastós: formed, molded – plural plastids) is a membrane-bound organelle found in the Cell (biology), cells of plants, algae, and some other eukaryotic organisms. They are considered to be intracellular endosy ...

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

s: ''

Sphaeropteris ''Sphaeropteris'' is a genus of tree fern 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 ''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. Des ...

'', '' Alsophila'', and ''Gymnosphaera + A. capensis''. , it remained unclear which of these groups should be considered genera and which subgenera. The

classification of 2016 (PPG I) accepts three genera, placing the ''Gymnosphaera'' clade within ''Alsophila'': *'' Alsophila'' R.Br., about 275 species *''

'' 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/ {{Taxonbar, from=Q133312 Fern families