Trochodendraceae
Encyclopedia
Trochodendraceae is a family
of flowering plants with two living genera found in southeast Asia. The two living species share the feature of secondary xylem without vessels, which is quite rare in angiosperms. As the vessel-free wood suggested primitiveness, these two species have attracted much taxonomic attention.
published in October 2009. Unlike the APG
and APG II system
s, this system places the family as the only family in the order Trochodendrales. It also includes Tetracentron
, synonymizing Tetracentraceae fully with Trochodenraceae.
The APG II system
, of 2003 retained the classification used in the 1998 APG system
recognizing Trochodendraceae as a family. APG and APG II did not place the family in an order
, leaving it among the basal lineages of the eudicots
. Both APG systems accepts this as a family of two modern species, but it does allow the option of separating out the family Tetracentraceae.
This segregation would lead to two families with one species each: Tetracentraceae with Tetracentron sinense and Trochodendraceae with Trochodendron aralioides
.
The Cronquist system
, of 1981, accepted both Trochodendraceae and Tetracentraceae as families and placed these in the order Trochodendrales, in subclass Hamamelidae, in class Magnoliopsida
.
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 flowering plants with two living genera found in southeast Asia. The two living species share the feature of secondary xylem without vessels, which is quite rare in angiosperms. As the vessel-free wood suggested primitiveness, these two species have attracted much taxonomic attention.
Classification
The current classification of Trochodendraceae is the APG III systemAPG III system
The APG III system of flowering plant classification is the third version of a modern, mostly molecular-based, system of plant taxonomy...
published in October 2009. Unlike the APG
APG system
The APG system of plant classification is the first, now obsolete, version of a modern, mostly molecular-based, system of plant taxonomy that was published in 1998 by the Angiosperm Phylogeny Group. It was superseded in 2003 by a revision, the APG II system, and then in 2009 by a further...
and APG II system
APG II system
The APG II system of plant classification is the second, now obsolete, version of a modern, mostly molecular-based, system of plant taxonomy that was published in April 2003 by the Angiosperm Phylogeny Group. It was a revision of the first APG system, published in 1998, and was superseded in 2009...
s, this system places the family as the only family in the order Trochodendrales. It also includes Tetracentron
Tetracentron
Tetracentron is a genus of flowering plant, the sole living species being Tetracentron sinense. It was formerly considered the sole genus in the family Tetracentraceae, though modern botanists include it in the family Trochodendraceae together with the genus Trochodendron.It is native to southern...
, synonymizing Tetracentraceae fully with Trochodenraceae.
The APG II system
APG II system
The APG II system of plant classification is the second, now obsolete, version of a modern, mostly molecular-based, system of plant taxonomy that was published in April 2003 by the Angiosperm Phylogeny Group. It was a revision of the first APG system, published in 1998, and was superseded in 2009...
, of 2003 retained the classification used in the 1998 APG system
APG system
The APG system of plant classification is the first, now obsolete, version of a modern, mostly molecular-based, system of plant taxonomy that was published in 1998 by the Angiosperm Phylogeny Group. It was superseded in 2003 by a revision, the APG II system, and then in 2009 by a further...
recognizing Trochodendraceae as a family. APG and APG II did not place the family in an order
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...
, leaving it among the basal lineages of the eudicots
Eudicots
Eudicots and Eudicotyledons are botanical terms introduced by Doyle & Hotton to refer to a monophyletic group of flowering plants that had been called tricolpates or non-Magnoliid dicots by previous authors...
. Both APG systems accepts this as a family of two modern species, but it does allow the option of separating out the family Tetracentraceae.
This segregation would lead to two families with one species each: Tetracentraceae with Tetracentron sinense and Trochodendraceae with Trochodendron aralioides
Trochodendron aralioides
Trochodendron aralioides, sometimes colloquially called "wheel tree", is a flowering plant and the sole living species in the genus Trochodendron, which also includes several extinct species. It was also often considered the sole species in the family Trochodendraceae, though botanists now include...
.
The Cronquist system
Cronquist system
The Cronquist system is a taxonomic classification system of flowering plants. It was developed by Arthur Cronquist in his texts An Integrated System of Classification of Flowering Plants and The Evolution and Classification of Flowering Plants .Cronquist's system places flowering plants into two...
, of 1981, accepted both Trochodendraceae and Tetracentraceae as families and placed these in the order Trochodendrales, in subclass Hamamelidae, in class Magnoliopsida
Magnoliopsida
Magnoliopsida is a valid botanical name for a class of flowering plants. By definition the class will include the family Magnoliaceae, but its circumscription can otherwise vary, being more inclusive or less inclusive depending upon the classification system being discussed.-Cronquist and...
.
External links
- Trochodendraceae in L. Watson and M.J. Dallwitz (1992 onwards). The families of flowering plants: descriptions, illustrations, identification, information retrieval. Version: 3 May 2006. http://delta-intkey.com.
- Trochodendraceae in the Flora of China
- NCBI Taxonomy Browser
- links at CSDL