Dicksoniaceae is a group of

tropical The tropics are the regions of Earth surrounding the Equator. They are defined in latitude by the Tropic of Cancer in the Northern Hemisphere at N and the Tropic of Capricorn in the Southern Hemisphere at S. The tropics are also referred to ...

subtropical The subtropical zones or subtropics are geographical and climate zones to the north and south of the tropics. Geographically part of the temperate zones of both hemispheres, they cover the middle latitudes from to approximately 35° north a ...

and warm temperate

fern 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 exce ...

s, treated as 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 ...

in the Pteridophyte Phylogeny Group classification of 2016 (PPG I), and counting 30-40 species.Scaly Tree Ferns Have Slow and Steady Diversification
/ref> Alternatively, the family may be sunk into a very broadly defined family

Cyatheaceae The Cyatheaceae are a family 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 ''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 subfamily Dicksonioideae. Most of the

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 ...

in the family are terrestrial ferns or have very short trunks compared to tree ferns of the family Cyatheaceae ''

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 c ...

''. However, some of the larger species can reach several metres in height. A number of others are

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 ...

s. They are found mostly in

regions in the Southern Hemisphere, as far south as southern

New Zealand New Zealand ( mi, Aotearoa ) is an island country in the southwestern Pacific Ocean. It consists of two main landmasses—the North Island () and the South Island ()—and over 700 smaller islands. It is the sixth-largest island coun ...

. Larger tree ferns in the genus ''

Cibotium ''Cibotium'' (from Greek , ''kibṓtion'', "little chest" or "box"), also known as manfern, is a genus of 11 species of tropical tree ferns. It is the only genus in family Cibotiaceae in the Pteridophyte Phylogeny Group classification of 2016 (PP ...

'' were formerly included in Dicksoniaceae, but are now segregated as the family Cibotiaceae.

Description

Species in the family are generally characterized by large pinnate

frond A frond is a large, divided leaf. In both common usage and botanical nomenclature, the leaves of ferns are referred to as fronds and some botanists restrict the term to this group. Other botanists allow the term frond to also apply to the lar ...

s, 1–4 m long. The family includes several species of tree ferns, which grow a single trunk, notably the species in '' Dicksonia''. All members of the family have long, tapering hairs composed of cells arranged end to end, unlike the scales characteristic of the Cyatheaceae ''s.l.''

Evolution

The family is thought to have arisen in the

Early Cretaceous The Early Cretaceous (geochronology, geochronological name) or the Lower Cretaceous (chronostratigraphy, chronostratigraphic name), is the earlier or lower of the two major divisions of the Cretaceous. It is usually considered to stretch from 145& ...

, based on molecular evidence. ''

Lophosoria Lophosoria is a genus of tree ferns within the family Dicksoniaceae. Although it is confined to tropical America in modern times, there is fossil evidence that it was once spread throughout Gondwana with the exception of New Zealand N ...

'' is known from fossil spores and leaf fragments from South America dating to the

Aptian The Aptian is an age in the geologic timescale or a stage in the stratigraphic column. It is a subdivision of the Early or Lower Cretaceous Epoch or Series and encompasses the time from 121.4 ± 1.0 Ma to 113.0 ± 1.0 Ma (million years ag ...

. The oldest fossil of '' Dicksonia'' is known from the

Eocene The Eocene ( ) Epoch is a geological epoch that lasted from about 56 to 33.9 million years ago (mya). It is the second epoch of the Paleogene Period in the modern Cenozoic Era. The name ''Eocene'' comes from the Ancient Greek (''ēṓs'', ...

of Antarctica. The widespread Jurassic-Cretaceous herbaceous fern genus ''

Coniopteris ''Coniopteris'' is an extinct genus of Mesozoic fern leaves with a fossil range from the Early Jurassic to the Cenomanian stage of the Late Cretaceous. It was widespread over both hemispheres during the Jurassic and Early Cretaceous, with over 130 ...

'' has historically been assigned to this family, but cladistic analysis suggests that it is more closely related to the

Polypodiales The order Polypodiales encompasses the major lineages of polypod ferns, which comprise more than 80% of today's fern species. They are found in many parts of the world including tropical, semitropical and temperate areas. Description Polypodiale ...

. Relationships of the three living genera, after.

Genera

Only three extant

are recognised in this

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 gr ...

family: * ''

Calochlaena ''Calochlaena'' is a genus of ferns within the family Dicksoniaceae. Although these ground ferns resemble bracken, they are only distantly related. Five species are known from Melanesia, Polynesia and eastern Australia. '' Calochlaena dubia'', i ...

'' (Maxon) M.D.Turner & R.A.White * '' Dicksonia'' L'Hér. * ''

'' C.Presl

References

Classification of Ferns and Allies
* Large, M.F. and J.E. Braggins (2004). ''Tree Ferns''. Timber Press. * Smith, A.R., K.M. Pryer, E. Schuettpelz, P. Korall, H. Schneider & P.G. Wolf 2006. ''Taxon'' 55(3): 705-731. {{Taxonbar, from=Q132779 Cyatheales Fern families