''Tetracarpaea'' is the only

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...

in the

flowering plant Flowering plants are plants that bear flowers and fruits, and form the clade Angiospermae (), commonly called angiosperms. The term "angiosperm" is derived from the Greek words ('container, vessel') and ('seed'), and refers to those plants th ...

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 ...

Tetracarpaeaceae.Richard K. Brummitt. 2007. "Tetracarpaeaceae" pages 316-317. In: Vernon H. Heywood, Richard K. Brummitt, Ole Seberg, and Alastair Culham. ''Flowering Plant Families of the World''. Firefly Books: Ontario, Canada. .Klaus Kubitzki. 2007. "Tetracarpaeaceae" pages 456-457. In: Klaus Kubitski (editor). ''The Families and Genera of Vascular Plants'' volume IX. Springer-Verlag: Berlin;Heidelberg, Germany. Some

taxonomists In biology, taxonomy () is the scientific study of naming, defining ( circumscribing) and classifying groups of biological organisms based on shared characteristics. Organisms are grouped into taxa (singular: taxon) and these groups are given ...

place it in the family

Haloragaceae Haloragaceae (the watermilfoil family) is a eudicot flowering plant family in the order Saxifragales, based on the phylogenetic APG system. In the Cronquist system, it was included in the order Haloragales. Description The Haloragaceae are ...

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 ...

'', expanding that family from its traditional

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 ...

to include ''

Penthorum ''Penthorum'' is a genus of plants in the order Saxifragales. They are erect herbaceous perennials about half a meter tall. The genus consists of two species, one from east Asia and one from eastern North America. It is variously classified in ...

'' and ''Tetracarpaea'', and sometimes '' Aphanopetalum'' as well.Shuguang Jian,

Pamela S. Soltis Pamela Soltis (born November 13, 1957) is an American botanist. She is a distinguished professor at the University of Florida, curator at the Florida Museum of Natural History, principal investigator of the Laboratory of Molecular Systematics an ...

, Matthew A. Gitzendanner, Michael J. Moore, Ruiqi Li, Tory A. Hendry, Yin-Long Qiu, Amit Dhingra, Charles D. Bell, and Douglas E. Soltis. 2008. "Resolving an Ancient, Rapid Radiation in Saxifragales". ''Systematic Biology'' 57(1):38-57. (see ''External links'' below). ''Tetracarpaea'' has one

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

, ''Tetracarpaea tasmannica'', an

evergreen In botany, an evergreen is a plant which has foliage that remains green and functional through more than one growing season. This also pertains to plants that retain their foliage only in warm climates, and contrasts with deciduous plants, which ...

, bushy

shrub A shrub (often also called a bush) is a small-to-medium-sized perennial woody plant. Unlike herbaceous plants, shrubs have persistent woody stems above the ground. Shrubs can be either deciduous or evergreen. They are distinguished from trees ...

from

subalpine Montane ecosystems are found on the slopes of mountains. The alpine climate in these regions strongly affects the ecosystem because temperatures fall as elevation increases, causing the ecosystem to stratify. This stratification is a crucial f ...

areas of

Tasmania ) , nickname = , image_map = Tasmania in Australia.svg , map_caption = Location of Tasmania in AustraliaCoordinates: , subdivision_type = Country , subdi ...

. It is variable in height, from 1.5 to 10 dm. The leaves are shiny and small, with prominent veins, and the ends of the branches are crowded with small, white flowers. It is not known in cultivation, but has been grown from cuttings.John W. Wrigley and Murray Fagg. 2003. ''Australian Native Plants'' fifth edition. Reed New Holland, Australia. ''Tetracarpaea'' has an odd mix of characters, and during the nineteenth and twentieth centuries, its affinities remained obscure. It was variously classified by different authors, usually with considerable uncertainty.Matthew H. Hils, William C. Dickison, Terry W. Lucansky, and William Louis Stern. 1988. "Comparative anatomy and systematics of woody Saxifragaceae: Tetracarpaea". ''American Journal of Botany'' 75(11):1687-1700.

Molecular phylogenetic Molecular phylogenetics () is the branch of phylogeny that analyzes genetic, hereditary molecular differences, predominantly in DNA sequences, to gain information on an organism's evolutionary relationships. From these analyses, it is possible to ...

analysis of

DNA sequence DNA sequencing is the process of determining the nucleic acid sequence – the order of nucleotides in DNA. It includes any method or technology that is used to determine the order of the four bases: adenine, guanine, cytosine, and thymine. Th ...

s has shown that ''Tetracarpaea'' is a member of the Haloragaceae alliance, an

informal Formal, formality, informal or informality imply the complying with, or not complying with, some set of requirements (forms, in Ancient Greek). They may refer to: Dress code and events * Formal wear, attire for formal events * Semi-formal attire ...

group A group is a number of persons or things that are located, gathered, or classed together. Groups of people * Cultural group, a group whose members share the same cultural identity * Ethnic group, a group whose members share the same ethnic ide ...

composed of the families Aphanopetalaceae, Tetracarpaeaceae, Penthoraceae, and Haloragaceae. These are four of the fourteenAngiosperm Phylogeny Group. 2009. "An update of the Angiosperm Phylogeny Group classification for the orders and families of flowering plants: APG III". ''Botanical Journal of the Linnean Society'' 161(2):105-121. (see ''External links'' below). or fifteen families in the order

Saxifragales The Saxifragales (saxifrages) are an order of flowering plants (Angiosperms). They are an extremely diverse group of plants which include trees, shrubs, perennial herbs, succulent and aquatic plants. The degree of diversity in terms of vege ...

Description

The following description is based on information from several sources.Armen L. Takhtajan (Takhtadzhian). ''Flowering Plants'' second edition (2009), pages 304-305. Springer Science+Business Media. . . (see ''External links'' below)

Frances Bodkin Frances (Fran) Bodkin (born 1937) is an Australian botanist and Dharawal elder. She is the author of ''Encyclopaedia Botanica: The Essential Reference Guide to Native and Exotic Plants in Australia'' (1986). In the 1970s she helped establish the Au ...

. 1986. ''Encyclopaedia Botanica: The Essential Reference Guide to Native and Exotic Plants in Australia''. Angus and Robertson, Publishers: New South Wales, Australia; London, England. ''Tetracarpaea tasmannica'' is a

glabrous Glabrousness (from the Latin '' glaber'' meaning "bald", "hairless", "shaved", "smooth") is the technical term for a lack of hair, down, setae, trichomes or other such covering. A glabrous surface may be a natural characteristic of all or part of ...

, erect and bushy

. It is variable in height, usually from 1.5 to 6 dm, but sometimes attaining a height of 1 m and a width of 7 dm. The

leaves A leaf (plural, : leaves) is any of the principal appendages of a vascular plant plant stem, stem, usually borne laterally aboveground and specialized for photosynthesis. Leaves are collectively called foliage, as in "autumn foliage", wh ...

are elliptic to

oblanceolate The following is a list of terms which are used to describe leaf morphology in the description and taxonomy of plants. Leaves may be simple (a single leaf blade or lamina) or compound (with several leaflets). The edge of the leaf may be regular o ...

, about 25 mm long and 8 mm wide, on a petiole about 2 mm long. The

veins Veins are blood vessels in humans and most other animals that carry blood towards the heart. Most veins carry deoxygenated blood from the tissues back to the heart; exceptions are the pulmonary and umbilical veins, both of which carry oxygenated b ...

are prominent and end near the margin. The margins are

serrate Serration is a saw-like appearance or a row of sharp or tooth-like projections. A serrated cutting edge has many small points of contact with the material being cut. By having less contact area than a smooth blade or other edge, the applied pr ...

crenate A leaf ( : leaves) is any of the principal appendages of a vascular plant stem, usually borne laterally aboveground and specialized for photosynthesis. Leaves are collectively called foliage, as in "autumn foliage", while the leaves, ste ...

. On both surfaces, the

epidermis The epidermis is the outermost of the three layers that comprise the skin, the inner layers being the dermis and hypodermis. The epidermis layer provides a barrier to infection from environmental pathogens and regulates the amount of water rele ...

is covered by a thick

cuticle A cuticle (), or cuticula, is any of a variety of tough but flexible, non-mineral outer coverings of an organism, or parts of an organism, that provide protection. Various types of "cuticle" are non- homologous, differing in their origin, structu ...

. The

inflorescence An inflorescence is a group or cluster of flowers arranged on a stem that is composed of a main branch or a complicated arrangement of branches. Morphologically, it is the modified part of the shoot of seed plants where flowers are formed o ...

s are dense, erect,

terminal Terminal may refer to: Computing Hardware * Terminal (electronics), a device for joining electrical circuits together * Terminal (telecommunication), a device communicating over a line * Computer terminal, a set of primary input and output dev ...

raceme A raceme ( or ) or racemoid is an unbranched, indeterminate type of inflorescence bearing flowers having short floral stalks along the shoots that bear the flowers. The oldest flowers grow close to the base and new flowers are produced as the s ...

s, up to 5 cm long. The

flower A flower, sometimes known as a bloom or blossom, is the reproductive structure found in flowering plants (plants of the division Angiospermae). The biological function of a flower is to facilitate reproduction, usually by providing a mechani ...

s appear in

autumn Autumn, also known as fall in American English and Canadian English, is one of the four temperate seasons on Earth. Outside the tropics, autumn marks the transition from summer to winter, in September ( Northern Hemisphere) or March ( Sou ...

. They are bisexual,

actinomorphic Floral symmetry describes whether, and how, a flower, in particular its perianth, can be divided into two or more identical or mirror-image parts. Uncommonly, flowers may have no axis of symmetry at all, typically because their parts are spirall ...

, and 5 to 10 mm wide. The 4

sepal A sepal () is a part of the flower of angiosperms (flowering plants). Usually green, sepals typically function as protection for the flower in bud, and often as support for the petals when in bloom., p. 106 The term ''sepalum'' was coined b ...

s persist to the maturity of the fruit. The 4

petal Petals are modified Leaf, leaves that surround the reproductive parts of flowers. They are often advertising coloration, brightly colored or unusually shaped to attract pollinators. All of the petals of a flower are collectively known as the ''c ...

s are

white White is the lightest color and is achromatic (having no hue). It is the color of objects such as snow, chalk, and milk, and is the opposite of black. White objects fully reflect and scatter all the visible wavelengths of light. White on ...

and

spatulate The following is a list of terms which are used to describe leaf morphology in the description and taxonomy of plants. Leaves may be simple (a single leaf blade or lamina) or compound (with several leaflets). The edge of the leaf may be regular ...

in shape. The

stamen The stamen (plural ''stamina'' or ''stamens'') is the pollen-producing reproductive organ of a flower. Collectively the stamens form the androecium., p. 10 Morphology and terminology A stamen typically consists of a stalk called the filame ...

s are either 4 or 8 in number. If 4, they are opposite (along the same radii as) the sepals. The

anther The stamen (plural ''stamina'' or ''stamens'') is the pollen-producing reproductive organ of a flower. Collectively the stamens form the androecium., p. 10 Morphology and terminology A stamen typically consists of a stalk called the filam ...

s are basifixed. The

ovary The ovary is an organ in the female reproductive system that produces an ovum. When released, this travels down the fallopian tube into the uterus, where it may become fertilized by a sperm. There is an ovary () found on each side of the body. ...

is superior and consists of 4

carpel Gynoecium (; ) is most commonly used as a collective term for the parts of a flower that produce ovules and ultimately develop into the fruit and seeds. The gynoecium is the innermost whorl of a flower; it consists of (one or more) ''pistils'' ...

s that are large compared to the rest of the flower. The carpels are usually separate, but occasionally 2 or 3 of them are fused at the base, or rarely, as far as halfway up. They are erect and stipitate with a suture along the ventral side. A

placenta The placenta is a temporary embryonic and later fetal organ that begins developing from the blastocyst shortly after implantation. It plays critical roles in facilitating nutrient, gas and waste exchange between the physically separate mater ...

runs along each side of the suture and bears 1 to 3 rows of numerous, tiny

ovule In seed plants, the ovule is the structure that gives rise to and contains the female reproductive cells. It consists of three parts: the ''integument'', forming its outer layer, the ''nucellus'' (or remnant of the megasporangium), and the fe ...

s. The ovules have been described as having one

integument In biology, an integument is the tissue surrounding an organism's body or an organ within, such as skin, a husk, shell, germ or rind. Etymology The term is derived from ''integumentum'', which is Latin for "a covering". In a transferred, or ...

or two. The ovary hardly enlarges after

anthesis Anthesis is the period during which a flower is fully open and functional. It may also refer to the onset of that period. The onset of anthesis is spectacular in some species. In ''Banksia'' species, for example, anthesis involves the extension ...

. The

fruit In botany, a fruit is the seed-bearing structure in flowering plants that is formed from the ovary after flowering. Fruits are the means by which flowering plants (also known as angiosperms) disseminate their seeds. Edible fruits in particu ...

consists of 4 follicles joined at the base. The seeds are numerous and about ½ mm long.

Relationships

Named by

William Jackson Hooker Sir William Jackson Hooker (6 July 178512 August 1865) was an English botanist and botanical illustrator, who became the first director of Kew when in 1841 it was recommended to be placed under state ownership as a botanic garden. At Kew he ...

in 1840, the name ''Tetracarpaea'' refers to the four conspicuous and separate carpels.William Jackson Hooker. 1840. ''Hooker's Icones Plantarum'' volume 3. page 56 and table 264. Longman, Orme, Brown, Green, and Longmans: London, England. (see ''External links'' below). At that time, he wrote: Hooker did not use the modern system of suffixes for

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. He placed ''Tetracarpaea'' in what would later be known as the family

Cunoniaceae Cunoniaceae is a family of 27 Genus, genera and about 335 species of woody plants in the order Oxalidales, mostly found in the tropical and wet temperate regions of the Southern Hemisphere. The greatest diversity of genera are in Australia and Ta ...

. From that time, until the end of the twentieth century, most authors put it in either Cunoniaceae,

Escalloniaceae Escalloniaceae is a family of flowering plants consisting of about 130 species in seven genera. In the APG II system it is one of eight families in the euasterids II clade (campanulids) that are unplaced as to order. More recent research has prov ...

, or

Saxifragaceae Saxifragaceae is a family of herbaceous perennial flowering plants, within the core eudicot order Saxifragales. The taxonomy of the family has been greatly revised and the scope much reduced in the era of molecular phylogenetic analysis. The f ...

. It was believed that these three families were related, but today, they are placed in separate orders.Peter F. Stevens. 2001 onwards. Angiosperm Phylogeny Website At: Missouri Botanical Garden Website. (see ''External links'' below). It is now known that Cunoniaceae belongs in

Oxalidales Oxalidales is an order of flowering plants, included within the rosid subgroup of eudicots. Compound leaves are common in Oxalidales and the majority of the species in this order have five or six sepals and petals. The following families are typic ...

.Jason C. Bradford, Helen C. Fortune-Hopkins, and Richard W. Barnes. 2004. "Cunoniaceae". pages 91-111. In: Klaus Kubitski (editor). ''The Families and Genera of Vascular Plants'' volume VI. Springer-Verlag: Berlin;Heidelberg, Germany. Escalloniaceae is even more distant from ''Tetracarpaea'', being a member of an

asterid In the APG IV system (2016) for the classification of flowering plants, the name asterids denotes a clade (a monophyletic group). Asterids is the largest group of flowering plants, with more than 80,000 species, about a third of the total floweri ...

group called the

campanulids In the APG IV system (2016) for the classification of flowering plants, the name asterids denotes a clade (a monophyletic group). Asterids is the largest group of flowering plants, with more than 80,000 species, about a third of the total flo ...

.Richard C. Winkworth, Johannes Lundberg, and Michael J. Donoghue. 2008. "Toward a resolution of Campanulid phylogeny, with special reference to the placement of Dipsacales". ''Taxon'' 57(1):53-65. In the

APG III system The APG III system of flowering plant classification is the third version of a modern, mostly molecular-based, system of plant taxonomy being developed by the Angiosperm Phylogeny Group (APG). Published in 2009, it was superseded in 2016 by a fur ...

, it is assigned to the monofamilial order

Escalloniales Escalloniaceae is a family of flowering plants consisting of about 130 species in seven genera. In the APG II system it is one of eight families in the euasterids II clade (campanulids) that are unplaced as to order. More recent research has prov ...

Phylogenetic In biology, phylogenetics (; from Greek φυλή/ φῦλον [] "tribe, clan, race", and wikt:γενετικός, γενετικός [] "origin, source, birth") is the study of the evolutionary history and relationships among or within groups o ...

analysis of DNA has placed ''Tetracarpaea'' in the order

, and in the "core Saxifragales", but no closer to Saxifragaceae. The family Saxifragaceae is now defined much more narrowly than it had been until 2001.Douglas E. Soltis, Robert K. Kuzoff, Mark E. Mort, Michael Zanis, Mark Fishbein, Larry Hufford, Jason Koontz, and Mary K. Arroyo. 2001. "Elucidating deep-level phylogenetic relationships in Saxifragaceae using sequences for six chloroplastic and nuclear DNA regions". ''Annals of the Missouri Botanical Garden'' 88(4):669-693.

History

After William Jackson Hooker named ''Tetracarpaea'' and placed it in Cunoniaceae, he was followed by

George Bentham George Bentham (22 September 1800 – 10 September 1884) was an English botanist, described by the weed botanist Duane Isely as "the premier systematic botanist of the nineteenth century". Born into a distinguished family, he initially studi ...

, who placed it in the same family.George Bentham. 1864. ''Flora Australiensis'' volume 2, page 445. Lovell Reeve & Co.: London, England. (see ''External links'' below). Bentham mistakenly attributed the name to "Hook.f." (

Joseph Dalton Hooker Sir Joseph Dalton Hooker (30 June 1817 – 10 December 1911) was a British botanist and explorer in the 19th century. He was a founder of geographical botany and Charles Darwin's closest friend. For twenty years he served as director of t ...

), an error that is still repeated today. In 1865, George Bentham and Joseph Hooker moved ''Tetracarpaea'' from Cunoniaceae to Escalloniaceae.George Bentham and Joseph Hooker. 1865. ''Genera Plantarum'' volume 1, part 2, pages 648-649. Lovell Reeve & Co.; Williams & Norgate: London, England. (see ''External links'' below).

Adolf Engler Heinrich Gustav Adolf Engler (25 March 1844 – 10 October 1930) was a German botanist. He is notable for his work on plant taxonomy and phytogeography, such as ''Die natürlichen Pflanzenfamilien'' (''The Natural Plant Families''), edited with ...

put ''Tetracarpaea'' in Saxifragaceae, but

defined A definition is a statement of the meaning of a term (a word, phrase, or other set of symbols). Definitions can be classified into two large categories: intensional definitions (which try to give the sense of a term), and extensional defini ...

the latter so widely that it included what is now Escalloniaceae as a subfamily. Engler first placed ''Tetracarpaea'' in subfamily Escallonioideae, then later moved it to its own subfamily.H.G. Adolf Engler. 1930. "Tetracarpaea" page 183. In: H.G. Adolf Engler and Karl A.E. Prantl (editors). 1930. ''Die Natürlichen Pflanzenfamilien'' volume 18a. Verlag von Wilhelm Engelmann: Leipzig, Germany. In 1943,

Takenoshin Nakai was a Japanese botanist. In 19191919. Notulae and Plantas Japoniae at Koreae X XI. The Botanical Magazine (Tokyo) 33(395): 193–194. and 19301930. Plantae Japonicae & Koreanae. The Botanical Magazine (Tokyo) 44(526): 508. he published papers on ...

put ''Tetracarpaea'' in a family to itself and was the first to use the term "Tetracarpaeaceae".Takenoshin Nakai. 1943. ''Chosakuronbun Mokuroku'': 244. 20 Jul 1943.James L. Reveal. 2008 onward. "A Checklist of Family and Suprafamilial Names for Extant Vascular Plants." At: Home page of James L. Reveal and C. Rose Broome. (see ''External links'' below). John Hutchinson did not follow suit, but placed it in Escalloniaceae.John Hutchinson ''The Families of Flowering Plants'' 3rd edition. 1973. Oxford University Press.

Arthur Cronquist Arthur John Cronquist (March 19, 1919 – March 22, 1992) was an American biologist, botanist and a specialist on Compositae. He is considered one of the most influential botanists of the 20th century, largely due to his formulation of the Cr ...

put ''Tetracarpaea'' in

Grossulariaceae ''Ribes'' is a genus of about 200 known species of flowering plants, most of them native to the temperate regions of the Northern Hemisphere. The various species are known as currants or gooseberries, and some are cultivated for their edible f ...

.Arthur John Cronquist. 1981. "Grossulariaceae" pages 558-561. In: ''An Integrated System of Classification of Flowering Plants''. Columbia University Press: New York, NY, USA. This family is now understood to contain only the genus

Ribes ''Ribes'' is a genus of about 200 known species of flowering plants, most of them native to the temperate regions of the Northern Hemisphere. The various species are known as currants or gooseberries, and some are cultivated for their edible f ...

and is

sister A sister is a woman or a girl who shares one or more parents with another individual; a female sibling. The male counterpart is a brother. Although the term typically refers to a familial relationship, it is sometimes used endearingly to refer to ...

to Saxifragaceae.

Armen Takhtajan Armen Leonovich Takhtajan or Takhtajian ( hy, Արմեն Լևոնի Թախտաջյան; russian: Армен Леонович Тахтаджян; surname also transliterated Takhtadjan, Takhtadzhi︠a︡n or Takhtadzhian, pronounced takh-tuh-JA ...

has at different times put ''Tetracarpaea'' in Escalloniaceae and in Tetracarpaeaceae. Most recently, in 2009, he put it in Tetracarpaeaceae. In 1988, Matthew H. Hils, et alii, did a detailed study of the

anatomy Anatomy () is the branch of biology concerned with the study of the structure of organisms and their parts. Anatomy is a branch of natural science that deals with the structural organization of living things. It is an old science, having its ...

of the

wood Wood is a porous and fibrous structural tissue found in the stems and roots of trees and other woody plants. It is an organic materiala natural composite of cellulose fibers that are strong in tension and embedded in a matrix of lignin th ...

and leaves of ''Tetracarpaea''. They concluded that ''Tetracarpaea'' was much closer to Saxifragaceae than to Cunoniaceae or Escalloniaceae. The first

molecular phylogenetic Molecular phylogenetics () is the branch of phylogeny that analyzes genetic, hereditary molecular differences, predominantly in DNA sequences, to gain information on an organism's evolutionary relationships. From these analyses, it is possible to ...

studies of the order Saxifragales were inconclusive because their results had only weak statistical support. In 2008, by comparing

s of the entire invert repeat region of the

chloroplast A chloroplast () is a type of membrane-bound organelle known as a plastid that conducts photosynthesis mostly in plant and algal cells. The photosynthetic pigment chlorophyll captures the energy from sunlight, converts it, and stores it in ...

genome In the fields of molecular biology and genetics, a genome is all the genetic information of an organism. It consists of nucleotide sequences of DNA (or RNA in RNA viruses). The nuclear genome includes protein-coding genes and non-coding ge ...

, Shuguang Jian et alii were able to determine the position of ''Tetracarpaea'' within Saxifragales. These results had strong bootstrap support.

Description

Relationships

History

References

External links