Dicksoniaceae
Encyclopedia
The Dicksoniaceae is a family
of tropical, subtropical and warm temperate fern
s. Most of the 5-6 genera
in the family are terrestrial ferns or have very short trunks compared to tree ferns of the family Cyatheaceae
. However, some of the larger species can reach several metres in height. A number of others are epiphyte
s. They are found mostly in tropical regions in the Southern Hemisphere
, as far south as southern New Zealand
.
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.
period.
are recognised in this monophyletic family:
Family (biology)
In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...
of tropical, subtropical and warm temperate fern
Fern
A fern is any one of a group of about 12,000 species of plants belonging to the botanical group known as Pteridophyta. Unlike mosses, they have xylem and phloem . They have stems, leaves, and roots like other vascular plants...
s. Most of the 5-6 genera
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
in the family are terrestrial ferns or have very short trunks compared to tree ferns of the family Cyatheaceae
Cyatheaceae
The Cyatheaceae is the scaly tree fern family and includes the world's tallest tree ferns, which reach heights up to 20 m. They are also very ancient plants, appearing in the fossil record in the late Jurassic, though the modern genera likely appeared in the Tertiary. Cyatheaceae is the largest...
. However, some of the larger species can reach several metres in height. A number of others are epiphyte
Epiphyte
An epiphyte is a plant that grows upon another plant non-parasitically or sometimes upon some other object , derives its moisture and nutrients from the air and rain and sometimes from debris accumulating around it, and is found in the temperate zone and in the...
s. They are found mostly in tropical regions in the Southern Hemisphere
Southern Hemisphere
The Southern Hemisphere is the part of Earth that lies south of the equator. The word hemisphere literally means 'half ball' or "half sphere"...
, as far south as southern New Zealand
New Zealand
New Zealand is an island country in the south-western Pacific Ocean comprising two main landmasses and numerous smaller islands. The country is situated some east of Australia across the Tasman Sea, and roughly south of the Pacific island nations of New Caledonia, Fiji, and Tonga...
.
Morphology
Species in the family are generally characterized by large pinnate frondFrond
The term frond refers to 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...
s, 1–4 m long. The family includes several species of tree ferns, which grow a single trunk, notably the species in Dicksonia
Dicksonia
Dicksonia is a genus of tree ferns in the order Cyatheales. It is regarded as related to Cyathea, but is considered more primitive, dating back at least to the Jurassic and Cretaceous periods. The fossil record includes stems, pinnules, and spores....
. All members of the family have long, tapering hairs composed of cells arranged end to end, unlike the scales characteristic of the Cyatheaceae.
Evolution
The ferns of family Dicksoniaceae are generally regarded as more primitive than those of the family Cyatheaceae, having originated in the early JurassicJurassic
The Jurassic is a geologic period and system that extends from about Mya to Mya, that is, from the end of the Triassic to the beginning of the Cretaceous. The Jurassic constitutes the middle period of the Mesozoic era, also known as the age of reptiles. The start of the period is marked by...
period.
Diversity
Only 3 extant generaGenus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
are recognised in this monophyletic family:
- CalochlaenaCalochlaenaCalochlaena is a genus of ferns within the Dicksoniaceae family. Although these ground ferns resemble bracken, they are only distantly related. Five species are known from Melanesia, Polynesia and eastern Australia. Calochlaena dubia, is a common fern of the east coast of Australia...
- DicksoniaDicksoniaDicksonia is a genus of tree ferns in the order Cyatheales. It is regarded as related to Cyathea, but is considered more primitive, dating back at least to the Jurassic and Cretaceous periods. The fossil record includes stems, pinnules, and spores....
- LophosoriaLophosoriaLophosoria is a genus of tree ferns within the Dicksoniaceae family.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....