Trochodendron aralioides | |
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Scientific classification | |
Kingdom: | Plantae |
Clade: | Tracheophytes |
Clade: | Angiosperms |
Clade: | Eudicots |
Order: | Trochodendrales |
Family: | Trochodendraceae |
Genus: | Trochodendron |
Species: | T. aralioides |
Binomial name | |
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 distinct genus Tetracentron in the same family. T. aralioides is native to Japan, southern Korea and Taiwan. Growing in lower temperate montane mixed forests in Japan, and broad-leaved evergreen forest in the central mountain ranges and Northern parts of Taiwan. [1]
It is an evergreen tree or large shrub growing to 20 m tall. The leaves are borne in tight spirals at the apex of the year's growth, each leaf leathery dark green, simple broad lanceolate, 6–14 cm long and 3–8 cm broad, with a crenate margin. The flowers are produced 10–20 together in a racemose cyme 5–13 cm diameter; each flower is 15–18 mm diameter, yellowish green, without petals, but with a conspicuous ring of 40–70 stamens surrounding the 4–11 carpels. The fruit is 2 cm diameter, woody, star-shaped, composed of 4–11 follicles, each follicle containing several seeds.
Trochodendron aralioides shares with Tetracentron the very unusual feature in angiosperms, of lacking vessel elements in its wood. [2] This has long been considered a very primitive character, resulting in the classification of these two genera in a basal position in the angiosperms; however, genetic research by the Angiosperm Phylogeny Group has shown it to be in a less basal position (early in the eudicots), suggesting the absence of vessel elements is a secondarily evolved character, not a primitive one. [3]
From sequencing the chromosome scale (19 chromosomes and 1.614 Gb in size) genome of the species it was seen that the divergence time between T. aralioides and its common ancestor with the core eudicots was ~124.2 Mya. [4]
The Magnoliaceae are a flowering plant family, the magnolia family, in the order Magnoliales. It consists of two genera: Magnolia and Liriodendron.
The Buxales are a small order of eudicot flowering plants, recognized by the APG IV system of 2016. The order includes the family Buxaceae; the families Didymelaceae and Haptanthaceae may also be recognized or may be included in the Buxaceae. Many members of the order are evergreen shrubs or trees, although some are herbaceous perennials. They have separate "male" (staminate) and "female" (carpellate) flowers, mostly on the same plant. Some species are of economic importance either for the wood they produce or as ornamental plants.
Amborella is a monotypic genus of understory shrubs or small trees endemic to the main island, Grande Terre, of New Caledonia in the southwest Pacific Ocean. The genus is the only member of the family Amborellaceae and the order Amborellales and contains a single species, Amborella trichopoda. Amborella is of great interest to plant systematists because molecular phylogenetic analyses consistently place it as the sister group to all other flowering plants, meaning it was the earliest group to evolve separately from all other flowering plants.
Drosophyllum is a genus of carnivorous plants containing the single species Drosophyllum lusitanicum, commonly known as Portuguese sundew or dewy pine. In appearance, it is similar to the related genus Drosera, and to the much more distantly related Byblis.
Aextoxicon is a genus of dioecious trees native to southern Chile and Argentina. It is the only genus in the monotypic family Aextoxicaceae, and is itself represented by the olivillo. It is a large evergreen tree native to the forests of the Valdivian temperate rain forests and Magellanic subpolar forests of the Pacific coast of southern Chile, where it forms is a canopy tree in the broadleaf forests. It can reach 15 m tall.
Griselinia is a genus of seven species of shrubs and trees, with a highly disjunct distribution native to New Zealand and South America. It is a classic example of the Antarctic flora. It is the sole genus in the family Griseliniaceae. In the past it was often placed in Cornaceae but differs from that in many features.
Gomortega keule is a species of tree endemic to Chile. It is the sole species of the genus Gomortega and, according to the APG IV system of 2016, of the monotypic family Gomortegaceae, assigned to the order Laurales in the clade magnoliids.
Sabiaceae is a family of flowering plants that were placed in the order Proteales according to the APG IV system. It comprises three genera, Meliosma, Ophiocaryon and Sabia, with 66 known species, native to tropical to warm temperate regions of southern Asia and the Americas. The family has also been called Meliosmaceae Endl., 1841, nom. rej.
Trochodendron is a genus of flowering plants with one living species, Trochodendron aralioides, and six extinct species known from the fossil record. It was often considered the sole genus in the family Trochodendraceae, though botanists now also include the distinct genus Tetracentron in the family.
Tetracentron is a genus of flowering plant with a sole living species being Tetracentron sinense and several extinct species. It was formerly considered the sole genus in the family Tetracentraceae, though it is now included in the family Trochodendraceae together with the genus Trochodendron.
Trochodendraceae is the only family of flowering plants in the order Trochodendrales. It comprises two extant genera, each with a single species along with up to five additional extinct genera and a number of extinct species. The living species are native to south east Asia. The two living species both have secondary xylem without vessel elements, which is quite rare in angiosperms. As the vessel-free wood suggests primitiveness, these two species have attracted much taxonomic attention.
Asteropeia is a genus of flowering plants. The genus contains 8 known species of shrubs and small trees, all endemic to Madagascar. It is the sole genus in family Asteropeiaceae. Members of the family are evergreen trees or shrubs.
Tetracentron sinense is a flowering plant native to Asia and the sole living species in the genus Tetracentron. It was formerly considered the sole species in the family Tetracentraceae, though Tetracentron is now included in the family Trochodendraceae together with the genus Trochodendron.
Aphloia is a genus of flowering plants that contains a single species, Aphloia theiformis, the sole species of the monogeneric family Aphloiaceae. It is a species of evergreen shrubs or small trees occurring in East Africa, Madagascar, the Mascarene Islands and the Seychelles.
Geissoloma is a genus of flowering plants in the monotypic family Geissolomataceae, native to the Cape Province of South Africa. Geissoloma marginatum is the only species in the family. It is sometimes called guyalone in English. The plants are xerophytic evergreen shrubs and are known to accumulate aluminum.
Trochodendron nastae is an extinct species of flowering plant in the family Trochodendraceae known from fossil leaves found in the early Eocene Ypresian stage Klondike Mountain Formation deposits of northern Washington state. T. nastae is one of the oldest members of the genus Trochodendron, which includes the living species T. aralioides, native to Japan, southern Korea and Taiwan and the coeval extinct species T. drachukii from the McAbee Fossil Beds near Cache Creek, British Columbia.
Trochodendron drachukii is an extinct species of flowering plants in the family Trochodendraceae known from a fossil fruiting structure found in the early Ypresian age Eocene fossils found in British Columbia, Canada. T. drachukii is one of the oldest members of the genus Trochodendron, which includes the living species T. aralioides, native to Japan, southern Korea and Taiwan and the coeval extinct species T. nastae from Washington state, United States.
Pentacentron is an extinct genus of flowering plant in the family Trochodendraceae, consisting of the single species Pentacentron sternhartae. The genus is known from fossil fruits found in the early Eocene deposits of northern Washington state, United States. P. sternhartae are possibly the fruits belonging to the extinct trochodendraceous leaves Tetracentron hopkinsii.
Tetracentron hopkinsii is an extinct species of flowering plant in the family Trochodendraceae. The species is known from fossil leaves found in the early Eocene deposits of northern Washington state, United States and south Central British Columbia. The species was first described from fossil leaves found in the Allenby Formation. T. hopkinsii are possibly the leaves belonging to the extinct trochodendraceous fruits Pentacentron sternhartae.
Paraconcavistylon is an extinct genus of flowering plant in the family Trochodendraceae comprises a single species, Paraconcavistylon wehrii. The genus is known from fossil fruits and leaves found in the early Eocene deposits of northern Washington state, United States, and southern British Columbia, Canada. The species was initially described as a member of the related extinct genus Concavistylon as "Concavistylon" wehrii, but subsequently moved to the new genus Paraconcavistylon in 2020 after additional study.