Tetracarpaea
Encyclopedia
Tetracarpaea is the only genus
in the flowering plant
family
Tetracarpaeaceae. Some taxonomists
place it in the family Haloragaceae
sensu lato, expanding that family from its traditional circumscription
to include Penthorum
and Tetracarpaea, and sometimes Aphanopetalum
as well.
Tetracarpaea has one species
, Tetracarpaea tasmannica, an evergreen
, bushy shrub
from subalpine
areas of Tasmania
. 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.
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. Molecular phylogenetic analysis of DNA sequence
s has shown that Tetracarpaea is a member of the Haloragaceae alliance, an informal
group
composed of the families Aphanopetalaceae, Tetracarpaeaceae, Penthoraceae, and Haloragaceae. These are four of the fourteen or fifteen families in the order
Saxifragales
.
Tetracarpaea tasmannica is a glabrous
, evergreen
, erect and bushy shrub
. 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
are elliptic to oblanceolate
, about 25 mm long and 8 mm wide, on a petiole
about 2 mm long. The veins are prominent and end near the margin. The margins are serrate
or crenate. On both surfaces, the epidermis
is covered by a thick cuticle
.
The inflorescence
s are dense, erect, terminal raceme
s, up to 5 cm long. The flower
s appear in autumn
. They are bisexual, actinomorphic, and 5 to 10 mm wide. The 4 sepal
s persist to the maturity
of the fruit. The 4 petal
s are white
and spatulate in shape.
The stamen
s are either 4 or 8 in number. If 4, they are opposite (along the same radii as) the sepals. The anthers are basifixed.
The ovary
is superior and consists of 4 carpels 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 runs along each side of the suture and bears 1 to 3 rows of numerous, tiny ovule
s. The ovules have been described as having one integument
or two.
The ovary hardly enlarges after anthesis
. The fruit
consists of 4 follicles
joined at the base. The seeds are numerous and about ½ mm long.
in 1840, the name Tetracarpaea refers to the four conspicuous and separate carpels. At that time, he wrote:
Hooker did not use the modern system of suffixes for taxonomic rank
s. He placed Tetracarpaea in what would later be known as the family Cunoniaceae
. From that time, until the end of the twentieth century, most authors put it in either Cunoniaceae, Escalloniaceae
, or Saxifragaceae
. It was believed that these three families were related, but today, they are placed in separate orders.
It is now known that Cunoniaceae belongs in Oxalidales
. Escalloniaceae is even more distant from Tetracarpaea, being a member of an asterid group called the campanulids. In the APG III system
, it is assigned to the monofamilial order Escalloniales. Phylogenetic analysis of DNA
has placed Tetracarpaea in the order Saxifragales
, 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.
, who placed it in the same family. Bentham mistakenly attributed the name to "Hook.f." (Joseph Dalton Hooker
), an error that is still repeated today. In 1865, George Bentham and Joseph Hooker moved Tetracarpaea from Cunoniaceae to Escalloniaceae.
Adolf Engler
put Tetracarpaea in Saxifragaceae, but defined
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.
In 1943, Takenoshin Nakai
put Tetracarpaea in a family to itself and was the first to use the term "Tetracarpaeaceae". John Hutchinson
did not follow suit, but placed it in Escalloniaceae.
Arthur Cronquist
put Tetracarpaea in Grossulariaceae. This family is now understood to contain only the genus Ribes
and is sister to Saxifragaceae. Armen Takhtajan 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
of the wood
and leaves of Tetracarpaea. They concluded that Tetracarpaea was much closer to Saxifragaceae than to Cunoniaceae or Escalloniaceae.
The first molecular phylogenetic studies of the order Saxifragales were inconclusive because their results had only weak statistical support
. In 2008, by comparing DNA sequence
s of the entire invert repeat
region of the chloroplast
genome
, Shuguang Jian et alii were able to determine the position of Tetracarpaea within Saxifragales. These results had strong bootstrap
support.
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 flowering plant
Flowering plant
The flowering plants , also known as Angiospermae or Magnoliophyta, are the most diverse group of land plants. Angiosperms are seed-producing plants like the gymnosperms and can be distinguished from the gymnosperms by a series of synapomorphies...
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...
Tetracarpaeaceae. Some taxonomists
Plant taxonomy
Plant taxonomy is the science that finds, describes, classifies, identifies, and names plants. It thus is one of the main branches of taxonomy.Plant taxonomy is closely allied to plant systematics, and there is no sharp boundary between the two...
place it in the family Haloragaceae
Haloragaceae
Haloragaceae is a dicotyledon flowering plant family in the order Saxifragales, based on the phylogenetic APG III system. In the Cronquist system, it was included in the order Haloragales.- Distribution :...
sensu lato, expanding that family from its traditional circumscription
Circumscription (taxonomy)
In taxonomy, circumscription is the definition of the limits of a taxonomic group of organisms. One goal of taxonomy is to achieve a stable circumscription for every taxonomic group. Achieving stability can be simple or difficult....
to include Penthorum
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 the family Saxifragaceae or its own family Penthoraceae....
and Tetracarpaea, and sometimes Aphanopetalum
Aphanopetalum
Aphanopetalum is a genus of twining shrubs or vines in the family Aphanopetalaceae which are endemic to Australia.The genus is placed alone in family Aphanopetalaceae, which is in turn now placed in order Saxifragales...
as well.
Tetracarpaea has one species
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
, Tetracarpaea tasmannica, an evergreen
Evergreen
In botany, an evergreen plant is a plant that has leaves in all seasons. This contrasts with deciduous plants, which completely lose their foliage during the winter or dry season.There are many different kinds of evergreen plants, both trees and shrubs...
, bushy shrub
Shrub
A shrub or bush is distinguished from a tree by its multiple stems and shorter height, usually under 5–6 m tall. A large number of plants may become either shrubs or trees, depending on the growing conditions they experience...
from subalpine
Alpine climate
Alpine climate is the average weather for a region above the tree line. This climate is also referred to as mountain climate or highland climate....
areas of Tasmania
Tasmania
Tasmania is an Australian island and state. It is south of the continent, separated by Bass Strait. The state includes the island of Tasmania—the 26th largest island in the world—and the surrounding islands. The state has a population of 507,626 , of whom almost half reside in the greater Hobart...
. 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
Plant propagation
Plant propagation is the process of creating new plants from a variety of sources: seeds, cuttings, bulbs and other plant parts. Plant propagation can also refer to the artificial or natural dispersal of plants.-Sexual propagation :...
from cuttings.
Tetracarpaea has an odd mix of characters, and during the nineteenth and twentieth centuries, its affinities remained obscure. It was variously classified
Biological classification
Biological classification, or scientific classification in biology, is a method to group and categorize organisms by biological type, such as genus or species. Biological classification is part of scientific taxonomy....
by different authors, usually with considerable uncertainty. Molecular phylogenetic analysis of DNA sequence
DNA sequence
The sequence or primary structure of a nucleic acid is the composition of atoms that make up the nucleic acid and the chemical bonds that bond those atoms. Because nucleic acids, such as DNA and RNA, are unbranched polymers, this specification is equivalent to specifying the sequence of...
s has shown that Tetracarpaea is a member of the Haloragaceae alliance, an informal
Taxonomic rank
In biological classification, rank is the level in a taxonomic hierarchy. Examples of taxonomic ranks are species, genus, family, and class. Each rank subsumes under it a number of less general categories...
group
Clade
A clade is a group consisting of a species and all its descendants. In the terms of biological systematics, a clade is a single "branch" on the "tree of life". The idea that such a "natural group" of organisms should be grouped together and given a taxonomic name is central to biological...
composed of the families Aphanopetalaceae, Tetracarpaeaceae, Penthoraceae, and Haloragaceae. These are four of the fourteen or fifteen families in the order
Order (biology)
In scientific classification used in biology, the order is# a taxonomic rank used in the classification of organisms. Other well-known ranks are life, domain, kingdom, phylum, class, family, genus, and species, with order fitting in between class and family...
Saxifragales
Saxifragales
Saxifragales is an order of flowering plants. Their closest relatives are a large eudicot group known as the rosids by the definition of rosids given in the APG II classification system. Some authors define the rosids more widely, including Saxifragales as their most basal group. Saxifragales is...
.
Description
The following description is based on information from several sources.Tetracarpaea tasmannica is a glabrous
Glabrousness
Glabrousness is the technical term for an anatomically atypical lack of hair, down, or similar structures...
, evergreen
Evergreen
In botany, an evergreen plant is a plant that has leaves in all seasons. This contrasts with deciduous plants, which completely lose their foliage during the winter or dry season.There are many different kinds of evergreen plants, both trees and shrubs...
, erect and bushy shrub
Shrub
A shrub or bush is distinguished from a tree by its multiple stems and shorter height, usually under 5–6 m tall. A large number of plants may become either shrubs or trees, depending on the growing conditions they experience...
. 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
Leaf
A leaf is an organ of a vascular plant, as defined in botanical terms, and in particular in plant morphology. Foliage is a mass noun that refers to leaves as a feature of plants....
are elliptic to oblanceolate
Leaf shape
In botany, leaf shape is characterised with the following terms :* Acicular : Slender and pointed, needle-like* Acuminate : Tapering to a long point...
, about 25 mm long and 8 mm wide, on a petiole
Petiole (botany)
In botany, the petiole is the stalk attaching the leaf blade to the stem. The petiole usually has the same internal structure as the stem. Outgrowths appearing on each side of the petiole are called stipules. Leaves lacking a petiole are called sessile, or clasping when they partly surround the...
about 2 mm long. The veins are prominent and end near the margin. The margins are serrate
Leaf shape
In botany, leaf shape is characterised with the following terms :* Acicular : Slender and pointed, needle-like* Acuminate : Tapering to a long point...
or crenate. On both surfaces, the epidermis
Epidermis (botany)
The epidermis is a single-layered group of cells that covers plants' leaves, flowers, roots and stems. It forms a boundary between the plant and the external environment. The epidermis serves several functions, it protects against water loss, regulates gas exchange, secretes metabolic compounds,...
is covered by a thick cuticle
Plant cuticle
Plant cuticles are a protective waxy covering produced only by the epidermal cells of leaves, young shoots and all other aerial plant organs without periderm...
.
The inflorescence
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. Strictly, it is the part of the shoot of seed plants where flowers are formed and which is accordingly modified...
s are dense, erect, terminal raceme
Raceme
A raceme is a type of inflorescence that is unbranched and indeterminate and bears pedicellate flowers — flowers having short floral stalks called pedicels — along the axis. In botany, axis means a shoot, in this case one bearing the flowers. In a raceme, the oldest flowers are borne...
s, up to 5 cm long. The flower
Flower
A flower, sometimes known as a bloom or blossom, is the reproductive structure found in flowering plants . The biological function of a flower is to effect reproduction, usually by providing a mechanism for the union of sperm with eggs...
s appear in autumn
Autumn
Autumn is one of the four temperate seasons. Autumn marks the transition from summer into winter usually in September or March when the arrival of night becomes noticeably earlier....
. They are bisexual, actinomorphic, and 5 to 10 mm wide. The 4 sepal
Sepal
A sepal is a part of the flower of angiosperms . Collectively the sepals form the calyx, which is the outermost whorl of parts that form a flower. Usually green, sepals have the typical function of protecting the petals when the flower is in bud...
s persist to the maturity
Ripening
Ripening is a process in fruits that causes them to become more palatable. In general, a fruit becomes sweeter, less green, and softer as it ripens. Even though the acidity of fruit increases as it ripens, the higher acidity level does not make the fruit seem tarter, which can lead to the...
of the fruit. The 4 petal
Petal
Petals are modified leaves that surround the reproductive parts of flowers. They often are brightly colored or unusually shaped to attract pollinators. Together, all of the petals of a flower are called a corolla. Petals are usually accompanied by another set of special leaves called sepals lying...
s are white
White
White is a color, the perception of which is evoked by light that stimulates all three types of color sensitive cone cells in the human eye in nearly equal amounts and with high brightness compared to the surroundings. A white visual stimulation will be void of hue and grayness.White light can be...
and spatulate in shape.
The stamen
Stamen
The stamen is the pollen producing reproductive organ of a flower...
s are either 4 or 8 in number. If 4, they are opposite (along the same radii as) the sepals. The anthers are basifixed.
The ovary
Ovary (plants)
In the flowering plants, an ovary is a part of the female reproductive organ of the flower or gynoecium. Specifically, it is the part of the pistil which holds the ovule and is located above or below or at the point of connection with the base of the petals and sepals...
is superior and consists of 4 carpels 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 runs along each side of the suture and bears 1 to 3 rows of numerous, tiny ovule
Ovule
Ovule means "small egg". 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 , and the megaspore-derived female gametophyte in its center...
s. The ovules have been described as having one integument
Ovule
Ovule means "small egg". 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 , and the megaspore-derived female gametophyte in its center...
or two.
The ovary hardly enlarges after anthesis
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 of the style far beyond the upper perianth parts...
. The fruit
Fruit
In broad terms, a fruit is a structure of a plant that contains its seeds.The term has different meanings dependent on context. In non-technical usage, such as food preparation, fruit normally means the fleshy seed-associated structures of certain plants that are sweet and edible in the raw state,...
consists of 4 follicles
Follicle (fruit)
In botany, a follicle is a dry unilocular many-seeded fruit formed from one carpel and dehiscing by the ventral suture in order to release seeds, such as in larkspur, magnolia, banksia, peony and milkweed....
joined at the base. The seeds are numerous and about ½ mm long.
Relationships
Named by William Jackson HookerWilliam Jackson Hooker
Sir William Jackson Hooker, FRS was an English systematic botanist and organiser. He held the post of Regius Professor of Botany at Glasgow University, and was the first Director of the Royal Botanic Gardens, Kew. He enjoyed the friendship and support of Sir Joseph Banks for his exploring,...
in 1840, the name Tetracarpaea refers to the four conspicuous and separate carpels. At that time, he wrote:
Hooker did not use the modern system of suffixes for taxonomic rank
Taxonomic rank
In biological classification, rank is the level in a taxonomic hierarchy. Examples of taxonomic ranks are species, genus, family, and class. Each rank subsumes under it a number of less general categories...
s. He placed Tetracarpaea in what would later be known as the family Cunoniaceae
Cunoniaceae
The Cunoniaceae is a family of 26 genera and about 350 species of woody plants in the Antarctic flora, with many laurifolia species with glossy leaves endemic to laurel forest habitat. The family is native to Australia, New Caledonia, New Guinea, New Zealand, southern South America, the Mascarene...
. From that time, until the end of the twentieth century, most authors put it in either Cunoniaceae, Escalloniaceae
Escalloniaceae
The Escalloniaceae is a family of flowering plants comprising about 130 species in seven genera. In the APG II system it is one of eight families in the euasterids II clade that are unplaced as to order...
, or Saxifragaceae
Saxifragaceae
Saxifragaceae is a plant family with about 460 known species in 36 genera. In Europe there are 12 genera.The flowers are hermaphroditic and actinomorphic...
. It was believed that these three families were related, but today, they are placed in separate orders.
It is now known that Cunoniaceae belongs in Oxalidales
Oxalidales
The Oxalidales are an order of flowering plants, included within the rosid subgroup of eudicots. The following families are typically placed here:* Family Brunelliaceae* Family Cephalotaceae * Family Connaraceae...
. Escalloniaceae is even more distant from Tetracarpaea, being a member of an asterid group called the campanulids. In the APG III system
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...
, it is assigned to the monofamilial order Escalloniales. Phylogenetic analysis of DNA
DNA
Deoxyribonucleic acid is a nucleic acid that contains the genetic instructions used in the development and functioning of all known living organisms . The DNA segments that carry this genetic information are called genes, but other DNA sequences have structural purposes, or are involved in...
has placed Tetracarpaea in the order Saxifragales
Saxifragales
Saxifragales is an order of flowering plants. Their closest relatives are a large eudicot group known as the rosids by the definition of rosids given in the APG II classification system. Some authors define the rosids more widely, including Saxifragales as their most basal group. Saxifragales is...
, 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.
History
After William Jackson Hooker named Tetracarpaea and placed it in Cunoniaceae, he was followed by George BenthamGeorge Bentham
George Bentham CMG FRS was an English botanist, characterized by Duane Isely as "the premier systematic botanist of the nineteenth century".- Formative years :...
, who placed it in the same family. Bentham mistakenly attributed the name to "Hook.f." (Joseph Dalton Hooker
Joseph Dalton Hooker
Sir Joseph Dalton Hooker OM, GCSI, CB, MD, FRS was one of the greatest British botanists and explorers of the 19th century. Hooker was a founder of geographical botany, and Charles Darwin's closest friend...
), an error that is still repeated today. In 1865, George Bentham and Joseph Hooker moved Tetracarpaea from Cunoniaceae to Escalloniaceae.
Adolf Engler
Adolf Engler
Heinrich Gustav Adolf Engler was a German botanist. He is notable for his work on plant taxonomy and phytogeography, like Die Natürlichen Pflanzenfamilien , edited with Karl A. E...
put Tetracarpaea in Saxifragaceae, but defined
Circumscription (taxonomy)
In taxonomy, circumscription is the definition of the limits of a taxonomic group of organisms. One goal of taxonomy is to achieve a stable circumscription for every taxonomic group. Achieving stability can be simple or difficult....
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.
In 1943, Takenoshin Nakai
Takenoshin Nakai
was a Japanese botanist.-External links:* * * by Yong Shik Kim and Mike Maunder from CURTIS'S Botanical Magazine, Royal Botanic Gardens, Kew, UK. Vol. 15: 141-146, 1998....
put Tetracarpaea in a family to itself and was the first to use the term "Tetracarpaeaceae". John Hutchinson
John Hutchinson (botanist)
John Hutchinson, OBE, FRS was a renowned English botanist, taxonomist and author.-Life and career:...
did not follow suit, but placed it in Escalloniaceae.
Arthur Cronquist
Arthur Cronquist
Arthur John Cronquist was a North American 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 Cronquist system. Two plant genera in the aster family have been named in his honor...
put Tetracarpaea in Grossulariaceae. This family is now understood to contain only the genus Ribes
Ribes
Ribes is a genus of about 150 species of flowering plants native throughout the temperate regions of the Northern Hemisphere. It is usually treated as the only genus in the family Grossulariaceae. Seven subgenera are recognized....
and is sister to Saxifragaceae. Armen Takhtajan 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
Plant anatomy
Plant anatomy or phytotomy is the general term for the study of the internal structure of plants. While originally it included plant morphology, which is the description of the physical form and external structure of plants, since the mid-20th century the investigations of plant anatomy are...
of the wood
Wood
Wood is a hard, fibrous tissue found in many trees. It has been used for hundreds of thousands of years for both fuel and as a construction material. It is an organic material, a natural composite of cellulose fibers embedded in a matrix of lignin which resists compression...
and leaves of Tetracarpaea. They concluded that Tetracarpaea was much closer to Saxifragaceae than to Cunoniaceae or Escalloniaceae.
The first molecular phylogenetic studies of the order Saxifragales were inconclusive because their results had only weak statistical support
Resampling (statistics)
In statistics, resampling is any of a variety of methods for doing one of the following:# Estimating the precision of sample statistics by using subsets of available data or drawing randomly with replacement from a set of data points # Exchanging labels on data points when performing significance...
. In 2008, by comparing DNA sequence
DNA sequence
The sequence or primary structure of a nucleic acid is the composition of atoms that make up the nucleic acid and the chemical bonds that bond those atoms. Because nucleic acids, such as DNA and RNA, are unbranched polymers, this specification is equivalent to specifying the sequence of...
s of the entire invert repeat
Inverted repeat
An inverted repeat is a sequence of nucleotides that is the reversed complement of another sequence further downstream.For example, 5'---GACTGC....GCAGTC---3'. When no nucleotides intervene between the sequence and its downstream complement, it is called a palindrome. Inverted repeats define the...
region of the chloroplast
Chloroplast
Chloroplasts are organelles found in plant cells and other eukaryotic organisms that conduct photosynthesis. Chloroplasts capture light energy to conserve free energy in the form of ATP and reduce NADP to NADPH through a complex set of processes called photosynthesis.Chloroplasts are green...
genome
Genome
In modern molecular biology and genetics, the genome is the entirety of an organism's hereditary information. It is encoded either in DNA or, for many types of virus, in RNA. The genome includes both the genes and the non-coding sequences of the DNA/RNA....
, Shuguang Jian et alii were able to determine the position of Tetracarpaea within Saxifragales. These results had strong bootstrap
Bootstrapping (statistics)
In statistics, bootstrapping is a computer-based method for assigning measures of accuracy to sample estimates . This technique allows estimation of the sample distribution of almost any statistic using only very simple methods...
support.
External links
- Shuguang Jian et alii on phylogeny of Saxifragales
- APG III
- Tetracarpaea In: Flowering Plants (Takhtajan)
- Tetracarpaea in Icones Plantarum
- Tetracarpaeaceae At: Saxifragales At: Angiosperm Phylogeny Website At: Missoure Botanical Garden Website
- Tetracarpaea In: Flora Australiensis
- Tetracarpaea In: Genera Plantarum 1865
- Family and Suprafamilial Names At: James L. Reveal