Tetracentron

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Tetracentron
Tetracentron sinense - Feuilles et fleurs-3.jpg
Tetracentron sinense, leaves and flowers
Scientific classification OOjs UI icon edit-ltr.svg
Kingdom: Plantae
Clade: Tracheophytes
Clade: Angiosperms
Clade: Eudicots
Order: Trochodendrales
Family: Trochodendraceae
Genus: Tetracentron
Oliv.
Species

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 .

Contents

Range

The living Tetracentron sinense is native to southern China and the eastern Himalaya, where it grows at altitudes of 1,100–3,500 m (3,600–11,500 ft) in a temperate climate; it has no widely used common name in English, though is sometimes called "spur-leaf".[ citation needed ]

Wood vessels

Tetracentron shares with Trochodendron the feature, very unusual in angiosperms, of lacking vessel elements in its wood. 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, research in Molecular phylogenetics by the Angiosperm Phylogeny Group and others has shown that these two genera are not basal angiosperms, but basal eudicots. [1] [2] This suggests that the absence of vessel elements is a secondarily evolved character, not a primitive one.

Fossil record

The fossil record, extending back to the Eocene, shows a much wider distribution than modern times. Fossils of this genus have been found in British Columbia, Canada,; [3] Alaska, [3] Washington state, United States; [3] and Iceland. [4] The Miocene Tetracentron atlanticum , described in 2008, is the first confirmed record of the genus in Europe. This species was described from pollen, fruits, and leaves found in Iceland.

Specimens from British Columbia and Washington state are found in a series of Eocene Lakes in the Okanagan Highlands region in association with several extinct Trochodendron species. The Paleogene species Tetracentron piperoides from Alaska is currently regarded as suspect due to the lack of associated fruits. [3]

Species

Related Research Articles

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<i>Trochodendron</i> Genus of flowing plants in the family Trochodendraceae

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.

<span class="mw-page-title-main">Trochodendraceae</span> Family of flowering plants

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.

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<i>Tetracentron sinense</i> Species of tree

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.

<i>Trochodendron aralioides</i> Species of tree

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<i>Trochodendron nastae</i> Extinct species of flowering plant

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.

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<span class="mw-page-title-main">McAbee Fossil Beds</span> Fossil bed in the Interior of British Columbia

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Concavistylon is an extinct genus of flowering plant in the family Trochodendraceae comprising a single species Concavistylon kvacekii. The genus is known from fossils found in Middle Miocene deposits of central Oregon. A second species "Concavistylon" wehrii was originally placed in Concavistylon, but subsequently moved to a new genus Paraconcavistylon in 2020.

<i>Pentacentron</i> Extinct genus of Trochodendralean plant

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.

<i>Tetracentron hopkinsii</i> Extinct species of flowering plant

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.

Trochodendron postnastae is an extinct species of flowering plant in the family Trochodendraceae. The species is known from fossils found in Middle Miocene deposits of central Oregon. T. postnastae are possibly the leaves belonging to the extinct trochodendraceous fruits Trochodendron rosayi.

Trochodendron rosayi is an extinct species of flowering plant in the family Trochodendraceae. The species is known from fossils found in Middle Miocene deposits of central Oregon. T. rosayi are possibly the fruits belonging to the extinct trochodendraceous leaf species Trochodendron postnastae.

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.

The paleoflora of the Eocene Okanagan Highlands includes all plant and fungi fossils preserved in the Eocene Okanagan Highlands Lagerstätten. The highlands are a series of Early Eocene geological formations which span an 1,000 km (620 mi) transect of British Columbia, Canada and Washington state, United States and are known for the diverse and detailed plant fossils which represent an upland temperate ecosystem immediately after the Paleocene-Eocene thermal maximum, and before the increased cooling of the middle and late Eocene to Oligocene. The fossiliferous deposits of the region were noted as early as 1873, with small amounts of systematic work happening in the 1880-90s on British Columbian sites, and 1920-30s for Washington sites. A returned focus and more detailed descriptive work on the Okanagan Highlands sites revived in the 1970's. The noted richness of agricultural plant families in Republic and Princeton floras resulted in the term "Eocene orchards" being used for the paleofloras.

The Paleobiota of the Klondike Mountain Formation comprises a diverse suite of Early Eocene plants and animals recovered from North Central Washington State. The formation outcrops in locations across the north western area of Ferry County, with major sites in Republic, north west of Curlew Lake, and on the Toroda Creek area. The formation is the southern most of the Eocene Okanagan Highlands, sharing much of the paleoflora and paleofauna with site across Central and southern British Columbia.

References

  1. Andreas Worberg, Dietmar Quandt, Anna-Magdalena Barniske, Cornelia Löhne, Khidir W. Hilu, and Thomas Borsch. 2007. "Phylogeny of basal eudicots: Insights from non-coding and rapidly evolving DNA." Organisms Diversity and Evolution7(1):55-77. (see "External links" below).
  2. Burleigh, J. Gordon; Hilu, Khidir W.; Soltis, Douglas E. (2009). "Inferring phylogenies with incomplete data sets: a 5-gene, 567-taxon analysis of angiosperms". BMC Evolutionary Biology. 9 (1): 61. doi: 10.1186/1471-2148-9-61 . PMC   2674047 .
  3. 1 2 3 4 Pigg, K.B.; Wehr, W.C.; Ickert-Bond, S.M. (2001), "Trochodendron and Nordenskioldia (Trochodendraceae) from the Middle Eocene of Washington State, U.S.A.", International Journal of Plant Sciences, 162 (5): 1187, doi:10.1086/321927
  4. Grímsson, F.; Denk, T.; Zetter, R. (2008), "Pollen, fruits, and leaves of Tetracentron (Trochodendraceae) from the Cainozoic of Iceland and western North America and their palaeobiogeographic implications", Grana, 73 (2)