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Trochodendraceae

Trochodendraceae is the only family of flowering plants in the order Trochodendrales. It comprises two extant genera, each with a single species[1] along with up to five additional extinct genera and a number of extinct species.[2] The living species are native to south east Asia. The two living species (Tetracentron sinense and Trochodendron aralioides) 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.

Trochodendraceae
Temporal range: Paleocene–Recent
Trochodendron aralioides
Scientific classification
Kingdom: Plantae
Clade: Tracheophytes
Clade: Angiosperms
Clade: Eudicots
Order: Trochodendrales
Takhtajan ex Cronquist
Family: Trochodendraceae
Eichler
Genera

Description

Tetracentron and Trochodendron are deciduous or evergreen trees, which grow to between 20–30 m (66–98 ft) tall, with Trochodendron sometimes sporting umbrella-shaped branches.

  • Leaves in spirals at the end of the branches (umbrella-like appearance, Trochodendron) or separate (Tetracentron), simple, serrulate or crenulate, with clorantoid teeth, palmately or pinnately divided, brochidodromous or actinodromous, ovate or obovate, with a cordate to cuneate base and acuminate apex, stalked, with thin stipules fused with the petiole (Tetracentron) or absent (Trochodendron). Idioblasts present, large, branched, sclerenchymatous in Trochodendron and secretory in Tetracentron. Stomata laterocytic or cyclocytic, hypostomatic.
  • Stems without xylematic vessels, with tracheids, heterogeneous xylem, uni- and multi-seriate, branches clearly differentiated in unifoliate brachyblasts and macroblasts with distichous phyllotaxis (Tetracentron), with nodes (1-)3(-multi)-lacunar, with (1)3(-7) leaf stems.
  • Hermaphroditic or androdioecious plants.
  • Terminal Inflorescence in erect, aggregated racemiforms (botryoid or small panicles) (Trochodendron) or defined, axillary, multi-floral amentoid spikes with the flower in whorls of 4 (Tetracentron). Bracts and bracteoles present or absent.
  • Perfect flowers, actinomorphic or dissymmetric, yellowish. Short, sub-conical, or hollow receptacle. Hypogynous disk absent. Reduced, very thin perianth, of 4 tepals in 2 decussate whorls (Tetracentron), or at most in a recognizable preantheric state (Trochodendron). Androecium of 4 decussate stamens in pairs of 40-70 in a spiral, non-versatile, basifixed, tetrasporangial, latrorso, apiculate anthers, dehiscence along 2 longitudinal valves in the theca. Gynoecium superior (Tetracentron) to slightly semi-inferior (Trochodendron), of 4-11(-17) carpels, syncarpous (alternating with the stamens in Tetracentron) to semicarpous, the dorsal part of the ovary expanded horizontally in the anthesis, abaxially nectariferous, with sunken stomata, free styles (stylodious), dry, papillose, decurrent ventral stigmas, 5-30 anatropous, apotropous, bitegmicous, crassinucelate, pendulous ovules per carpel, placentation marginal in 2 series or apicoaxial.
  • Fruit in ventricidal or slightly loculicidal capsule or an aggregate of dorsally and ventrally dehiscent semicarpical follicles, with basal and external styles.
  • Small, flattened, tapered seeds, 3–4 mm in length, with lateral, apical, chalazal wings, with thin testa, with abundant, oily and proteinaceous endosperm, small embryo, with 2 cotyledons.
  • Pollen in small, granular, spheroidal, tricolpate, tectated-columelliform monads (10-20 μm in diameter), the surface with interwoven bars parallel to the edges of the colpus, which are granular.
  • Chromosomal number: 2n = 48 in Tetracentron and 2n = 38, 40 in Trochodendron.

Ecology

Pollination is probably myriophyllous, even though Tetracentron shows a clear anemophilous syndrome. The pulverulent seeds are dispersed by the wind (anemochory). Trochodendron is present in both protandrous and protogynous forms that are self-compatible.

The plants are found in wooded formations, Trochodendron between 300 m and 2.700 m above sea level and Tetracentron between 1.100 m and 3.600 m above sea level.

Phytochemistry

Flavonoids (quercetin and kaempferol) and proanthocyanidins (cyanidin and delphinidin) are present. Epicuticular waxes are basically composed of nonacosan-10-ol.[citation needed] Tetracentron contains chalcones or dihydrochalcones. Trochodendron contains myricetin. Ellagic acid is absent.

Fossils

Trochodendron and the fossil genus Eotrochion are known from the Paleocene of Wyoming, which constitute the oldest records of the family.[2]

A diverse assemblage of trochodendraceous species have been described from the Eocene OKanagan Highlands in British Columbia and Northeastern Washington. The monotypic genera Paraconcavistylon and Pentacentron are accompanied by Tetracentron hopkinsii and the Trochodendron infructescence morphospecies Tr. drachukii plus the foliage morphospecies Tr. nastae.[3][2]

The fruit and wood genus Nordenskioeldia, along with the associated leaf morphogenus Zizyphoides have been considered part of Trochodendraceae, though phylogenetic analysis by Manchester et al (2020) suggested they might be better placed as a basal stem linage in the Trochodendrales, rather than as a crown group member of the family Trochodendraceae.[2]

Systematic position

The Trocodendraceae are a group of flowering plants that include the clade Eudicotyledoneae. In previous systems they have been related with the Cercidiphyllaceae and the Eupteleaceae, with which they share some characteristics that can be considered symplesiomorphic or convergent and that have been excluded from the order Trochodendrales because of molecular data leaving the Trocodendraceae isolated. Based on molecular and morphological data, the APW (Angiosperm Phylogeny Website) considers that it constitutes the only family in the Order Trochodendrales (cf. AP-website).

Classification

The current classification of Trochodendraceae is the APG IV system published in 2016, which maintains the circumscription of Trochodendraceae used in the APG III system published in October 2009. Unlike the APG and APG II systems, the later systems place the family as the only family in the order Trochodendrales. They also includes Tetracentron, synonymizing Tetracentraceae fully with Trochodenraceae.[4][5]

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.

Taxa included

The family includes two living genera with very different morphological characteristics:

  • Palmate leaves, with stipules, deciduous. Perianth of 4 tepals. Stamens 4. Carpels 4. Ovules 5-6 per carpel. Axillary inflorescence in amentoid spike.
Tetracentron Oliv., 1889. North-east India, Nepal, Bhutan, Burma, western and central China, Vietnam.
  • Pinnate leaves, without stipules, evergreen. Perianth absent. Stamens 40-70. Carpels (4-)6-11(-17). Ovules 15-30 per carpel. Terminal racemiform inflorescence, erect.
Trochodendron Siebold & Zucc., 1839. Japan, Taiwan, Korea.

References

  1. ^ Christenhusz, M. J. M. & Byng, J. W. (2016). "The number of known plants species in the world and its annual increase". Phytotaxa. 261 (3): 201–217. doi:10.11646/phytotaxa.261.3.1.
  2. ^ a b c d Manchester, S. R.; Kvaček, Z.; Judd, W. S. (2020). "Morphology, anatomy, phylogenetics and distribution of fossil and extant Trochodendraceae in the Northern Hemisphere". Botanical Journal of the Linnean Society. 195 (3): 467–484. doi:10.1093/botlinnean/boaa046.
  3. ^ Manchester, S.; Pigg, K. B.; Kvaček, Z; DeVore, M. L.; Dillhoff, R. M. (2018). "Newly recognized diversity in Trochodendraceae from the Eocene of western North America". International Journal of Plant Sciences. 179 (8): 663–676. doi:10.1086/699282. S2CID 92201595.
  4. ^ Angiosperm Phylogeny Group (2009). An update of the Angiosperm Phylogeny Group classification for the orders and families of flowering plants: APG III. Botanical Journal of the Linnean Society 161: 105-121.
  5. ^ Angiosperm Phylogeny Group (2016). "An update of the Angiosperm Phylogeny Group classification for the orders and families of flowering plants: APG IV". Botanical Journal of the Linnean Society. 181 (1): 1–20. doi:10.1111/boj.12385. ISSN 0024-4074.{{cite journal}}: CS1 maint: uses authors parameter (link)

Further reading

  • Endress, P.K. (1993). "Trochodendraceae.". Kubitzki, K., Rohwer, J.G. & Bittrich, V. (Editores). The Families and Genera of Vascular Plants. II. Flowering Plants - Dicotyledons. Springer-Verlag: Berlín. ISBN 978-3-540-55509-4.
  • Watson, L., and Dallwitz, M.J. (1992). "The families of flowering plants: descriptions, illustrations, identification, and information retrieval. Version: 29th July 2006". Retrieved 31 January 2007.{{cite web}}: CS1 maint: multiple names: authors list (link)

External links

trochodendraceae, only, family, flowering, plants, order, trochodendrales, comprises, extant, genera, each, with, single, species, along, with, five, additional, extinct, genera, number, extinct, species, living, species, native, south, east, asia, living, spe. Trochodendraceae is the only family of flowering plants in the order Trochodendrales It comprises two extant genera each with a single species 1 along with up to five additional extinct genera and a number of extinct species 2 The living species are native to south east Asia The two living species Tetracentron sinense and Trochodendron aralioides 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 TrochodendraceaeTemporal range Paleocene Recent PreꞒ Ꞓ O S D C P T J K Pg NTrochodendron aralioidesScientific classificationKingdom PlantaeClade TracheophytesClade AngiospermsClade EudicotsOrder TrochodendralesTakhtajan ex CronquistFamily TrochodendraceaeEichlerGenera Concavistylon Eotrochion Nordenskioeldia Paraconcavistylon Pentacentron Tetracentron Oliv Trochodendron Siebold amp Zucc wheel tree Zizyphoides Contents 1 Description 2 Ecology 3 Phytochemistry 4 Fossils 5 Systematic position 6 Classification 7 Taxa included 8 References 9 Further reading 10 External linksDescription EditThis section may be too technical for most readers to understand Please help improve it to make it understandable to non experts without removing the technical details October 2020 Learn how and when to remove this template message Tetracentron and Trochodendron are deciduous or evergreen trees which grow to between 20 30 m 66 98 ft tall with Trochodendron sometimes sporting umbrella shaped branches Leaves in spirals at the end of the branches umbrella like appearance Trochodendron or separate Tetracentron simple serrulate or crenulate with clorantoid teeth palmately or pinnately divided brochidodromous or actinodromous ovate or obovate with a cordate to cuneate base and acuminate apex stalked with thin stipules fused with the petiole Tetracentron or absent Trochodendron Idioblasts present large branched sclerenchymatous in Trochodendron and secretory in Tetracentron Stomata laterocytic or cyclocytic hypostomatic Stems without xylematic vessels with tracheids heterogeneous xylem uni and multi seriate branches clearly differentiated in unifoliate brachyblasts and macroblasts with distichous phyllotaxis Tetracentron with nodes 1 3 multi lacunar with 1 3 7 leaf stems Hermaphroditic or androdioecious plants Terminal Inflorescence in erect aggregated racemiforms botryoid or small panicles Trochodendron or defined axillary multi floral amentoid spikes with the flower in whorls of 4 Tetracentron Bracts and bracteoles present or absent Perfect flowers actinomorphic or dissymmetric yellowish Short sub conical or hollow receptacle Hypogynous disk absent Reduced very thin perianth of 4 tepals in 2 decussate whorls Tetracentron or at most in a recognizable preantheric state Trochodendron Androecium of 4 decussate stamens in pairs of 40 70 in a spiral non versatile basifixed tetrasporangial latrorso apiculate anthers dehiscence along 2 longitudinal valves in the theca Gynoecium superior Tetracentron to slightly semi inferior Trochodendron of 4 11 17 carpels syncarpous alternating with the stamens in Tetracentron to semicarpous the dorsal part of the ovary expanded horizontally in the anthesis abaxially nectariferous with sunken stomata free styles stylodious dry papillose decurrent ventral stigmas 5 30 anatropous apotropous bitegmicous crassinucelate pendulous ovules per carpel placentation marginal in 2 series or apicoaxial Fruit in ventricidal or slightly loculicidal capsule or an aggregate of dorsally and ventrally dehiscent semicarpical follicles with basal and external styles Small flattened tapered seeds 3 4 mm in length with lateral apical chalazal wings with thin testa with abundant oily and proteinaceous endosperm small embryo with 2 cotyledons Pollen in small granular spheroidal tricolpate tectated columelliform monads 10 20 mm in diameter the surface with interwoven bars parallel to the edges of the colpus which are granular Chromosomal number 2n 48 in Tetracentron and 2n 38 40 in Trochodendron Ecology EditPollination is probably myriophyllous even though Tetracentron shows a clear anemophilous syndrome The pulverulent seeds are dispersed by the wind anemochory Trochodendron is present in both protandrous and protogynous forms that are self compatible The plants are found in wooded formations Trochodendron between 300 m and 2 700 m above sea level and Tetracentron between 1 100 m and 3 600 m above sea level Phytochemistry EditFlavonoids quercetin and kaempferol and proanthocyanidins cyanidin and delphinidin are present Epicuticular waxes are basically composed of nonacosan 10 ol citation needed Tetracentron contains chalcones or dihydrochalcones Trochodendron contains myricetin Ellagic acid is absent Fossils EditTrochodendron and the fossil genus Eotrochion are known from the Paleocene of Wyoming which constitute the oldest records of the family 2 A diverse assemblage of trochodendraceous species have been described from the Eocene OKanagan Highlands in British Columbia and Northeastern Washington The monotypic genera Paraconcavistylon and Pentacentron are accompanied by Tetracentron hopkinsii and the Trochodendron infructescence morphospecies Tr drachukii plus the foliage morphospecies Tr nastae 3 2 The fruit and wood genus Nordenskioeldia along with the associated leaf morphogenus Zizyphoides have been considered part of Trochodendraceae though phylogenetic analysis by Manchester et al 2020 suggested they might be better placed as a basal stem linage in the Trochodendrales rather than as a crown group member of the family Trochodendraceae 2 Systematic position EditThe Trocodendraceae are a group of flowering plants that include the clade Eudicotyledoneae In previous systems they have been related with the Cercidiphyllaceae and the Eupteleaceae with which they share some characteristics that can be considered symplesiomorphic or convergent and that have been excluded from the order Trochodendrales because of molecular data leaving the Trocodendraceae isolated Based on molecular and morphological data the APW Angiosperm Phylogeny Website considers that it constitutes the only family in the Order Trochodendrales cf AP website Classification EditThe current classification of Trochodendraceae is the APG IV system published in 2016 which maintains the circumscription of Trochodendraceae used in the APG III system published in October 2009 Unlike the APG and APG II systems the later systems place the family as the only family in the order Trochodendrales They also includes Tetracentron synonymizing Tetracentraceae fully with Trochodenraceae 4 5 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 Taxa included EditThe family includes two living genera with very different morphological characteristics Palmate leaves with stipules deciduous Perianth of 4 tepals Stamens 4 Carpels 4 Ovules 5 6 per carpel Axillary inflorescence in amentoid spike Tetracentron Oliv 1889 North east India Nepal Bhutan Burma western and central China Vietnam Pinnate leaves without stipules evergreen Perianth absent Stamens 40 70 Carpels 4 6 11 17 Ovules 15 30 per carpel Terminal racemiform inflorescence erect Trochodendron Siebold amp Zucc 1839 Japan Taiwan Korea References Edit Christenhusz M J M amp Byng J W 2016 The number of known plants species in the world and its annual increase Phytotaxa 261 3 201 217 doi 10 11646 phytotaxa 261 3 1 a b c d Manchester S R Kvacek Z Judd W S 2020 Morphology anatomy phylogenetics and distribution of fossil and extant Trochodendraceae in the Northern Hemisphere Botanical Journal of the Linnean Society 195 3 467 484 doi 10 1093 botlinnean boaa046 Manchester S Pigg K B Kvacek Z DeVore M L Dillhoff R M 2018 Newly recognized diversity in Trochodendraceae from the Eocene of western North America International Journal of Plant Sciences 179 8 663 676 doi 10 1086 699282 S2CID 92201595 Angiosperm Phylogeny Group 2009 An update of the Angiosperm Phylogeny Group classification for the orders and families of flowering plants APG III Botanical Journal of the Linnean Society 161 105 121 Angiosperm Phylogeny Group 2016 An update of the Angiosperm Phylogeny Group classification for the orders and families of flowering plants APG IV Botanical Journal of the Linnean Society 181 1 1 20 doi 10 1111 boj 12385 ISSN 0024 4074 a href Template Cite journal html title Template Cite journal cite journal a CS1 maint uses authors parameter link Further reading EditEndress P K 1993 Trochodendraceae Kubitzki K Rohwer J G amp Bittrich V Editores The Families and Genera of Vascular Plants II Flowering Plants Dicotyledons Springer Verlag Berlin ISBN 978 3 540 55509 4 Watson L and Dallwitz M J 1992 The families of flowering plants descriptions illustrations identification and information retrieval Version 29th July 2006 Retrieved 31 January 2007 a href Template Cite web html title Template Cite web cite web a CS1 maint multiple names authors list link External links Edit Wikimedia Commons has media related to Trochodendraceae Retrieved from https en wikipedia org w index php title Trochodendraceae amp oldid 1095688363, wikipedia, wiki, book, books, library,

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