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Dipentodontaceae

Dipentodontaceae

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Encyclopedia
Dipentodon is a genus
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...

 of 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...

s in the 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...

 Dipentodontaceae
Dipentodontaceae
Dipentodon is a genus of flowering plants in the family Dipentodontaceae. Its only species, Dipentodon sinicus, is a small, deciduous tree native to southern China, Burma, and northern India. It has been little studied and until recently its affinities remained obscure.- Description :Dipentodon...

. Its only 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...

, Dipentodon sinicus, is a small, deciduous
Deciduous
Deciduous means "falling off at maturity" or "tending to fall off", and is typically used in reference to trees or shrubs that lose their leaves seasonally, and to the shedding of other plant structures such as petals after flowering or fruit when ripe...

 tree
Tree
A tree is a perennial woody plant. It is most often defined as a woody plant that has many secondary branches supported clear of the ground on a single main stem or trunk with clear apical dominance. A minimum height specification at maturity is cited by some authors, varying from 3 m to...

 native to southern China, Burma, and northern India. It has been little studied and until recently its affinities remained obscure.

Description


Dipentodon sinicus is a small, deciduous tree. The leaves are stipulate
Stipule
In botany, stipule is a term coined by Linnaeus which refers to outgrowths borne on either side of the base of a leafstalk...

, alternate, and simple, with 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...

 margins. 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...

 is variable in form, usually an abbreviated, umbel
Umbel
An umbel is an inflorescence which consists of a number of short flower stalks which are equal in length and spread from a common point, somewhat like umbrella ribs....

liform cyme  containing 25 to 30 small flowers. The flowers are actinomorphic and yellowish green. The 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 and 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 only weakly differentiated, usually 5, rarely to 7 in number, free, or united only at the base. The hypanthium
Hypanthium
A hypanthium is a floral structure consisting of the bases of the sepals, petals, and stamens fused together. Its presence is diagnostic of many families, including the Rosaceae, Grossulariaceae, and Fabaceae...

 is very short or else 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. The nectary disk is intrastaminal. The stamen
Stamen
The stamen is the pollen producing reproductive organ of a flower...

s are opposite the sepals. The ovary consists of three united carpels with two 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 per carpel. The ovary is 1-loculate
Locule
A locule is a small cavity or compartment within an organ or part of an organism ....

, but partly 3-loculate at its base. 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,...

 is a 1-seeded drupaceous
Drupe
In botany, a drupe is a fruit in which an outer fleshy part surrounds a shell of hardened endocarp with a seed inside. These fruits develop from a single carpel, and mostly from flowers with superior ovaries...

 capsule
Capsule (fruit)
In botany a capsule is a type of simple, dry fruit produced by many species of flowering plants. A capsule is a structure composed of two or more carpels that in most cases is dehiscent, i.e. at maturity, it splits apart to release the seeds within. A few capsules are indehiscent, for example...

.

History


Dipentodon was named and first described in 1911 by Stephen Troyte Dunn in what is now called the Kew Bulletin
Kew Bulletin
Kew Bulletin is a quarterly peer-reviewed scientific journal on plant and fungal taxonomy published by Springer Science+Business Media on behalf of the Royal Botanic Gardens, Kew. It was established in 1887...

. At that time, Dunn wrote:
Dipentodon was placed in its own family by Elmer Drew Merrill
Elmer Drew Merrill
Elmer Drew Merrill was an American botanist, specializing in the flora of the Asia-Pacific region.He was born in East Auburn, Maine, and attended the University of Maine where he received a B.S. in 1898...

 in 1941, but this placement was not generally followed. Instead, most authors put Dipentodon in the ill-defined and heterogeneous family Flacourtiaceae. In the twenty-first century, Flacourtiaceae is recognized by only a few taxonomists
Taxonomy
Taxonomy is the science of identifying and naming species, and arranging them into a classification. The field of taxonomy, sometimes referred to as "biological taxonomy", revolves around the description and use of taxonomic units, known as taxa...

, and then only in a much narrower sense
Sensu
Sensu is a Latin word meaning "in the sense of".It is used in a number of fields including biology, geology, linguistics, and law. Commonly it refers to how strictly or loosely an expression is used, but it also appears in expressions that indicate the convention or context of the usage.-Sensu and...

 than it had been. Dipentodon is unrelated to Flacourtiaceae sensu stricto, a segregate
Segregate (taxonomy)
In taxonomy, a segregate, or a segregate taxon is created when a taxon is split off, from another taxon. This other taxon will be better known, usually bigger, and will continue to exist, even after the segregate taxon has been split off...

 of Salicaceae
Salicaceae
Salicaceae are a family of flowering plants. Recent genetic studies summarized by the Angiosperm Phylogeny Group has greatly expanded the circumscription of the family to contain 55 genera....

. Molecular phylogenetic studies have led to the widespread acceptance of the family Dipentodontaceae and its placement in the order Huerteales
Huerteales
Huerteales is the botanical name for an order of flowering plants. It is one of the 17 orders that make up the large eudicot group known as the rosids in the APG III system of plant classification. Within the rosids, it is one of the orders in Malvidae, a group formerly known as eurosids II and...

. Some authors have defined the family as consisting only of Dipentodon. Others, following the recommendation of a 2006 study
Research
Research can be defined as the scientific search for knowledge, or as any systematic investigation, to establish novel facts, solve new or existing problems, prove new ideas, or develop new theories, usually using a scientific method...

, have included Perrottetia. When the APG II classification was published in 2003, the taxonomic position
Systematics
Biological systematics is the study of the diversification of terrestrial life, both past and present, and the relationships among living things through time. Relationships are visualized as evolutionary trees...

 of Dipentodon was still unknown and it was placed incertae sedis
Incertae sedis
, is a term used to define a taxonomic group where its broader relationships are unknown or undefined. Uncertainty at specific taxonomic levels is attributed by , , and similar terms.-Examples:*The fossil plant Paradinandra suecica could not be assigned to any...

 in the angiosperms. It was listed in the appendix under TAXA OF UNCERTAIN POSITION.

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