It has been suggested that Hydatellales be merged into this article. (Discuss) Proposed since November 2024. |
It has been suggested that Hydatellaceae be merged into this article. (Discuss) Proposed since November 2024. |
Trithuria | |
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Complete Trithuria submersa specimen | |
Scientific classification | |
Kingdom: | Plantae |
Clade: | Tracheophytes |
Clade: | Angiosperms |
Order: | Nymphaeales |
Family: | Hydatellaceae |
Genus: | Trithuria Hook.f. |
Type species | |
Trithuria submersa | |
Synonyms [1] | |
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Trithuria is a genus of small ephemeral aquatic herb that represent the only members of the family Hydatellaceae found in India, Australia, and New Zealand. [1] [2] Almost all described species of Trithuria are found in Australia, with the exception of T. inconspicua and T. konkanensis, from New Zealand and India respectively. [3] [4] Until DNA sequence data and a reinterpretation of morphology proved otherwise, these plants were believed to be monocots related to the grasses (Poaceae). They are unique in being the only plants besides two members of Triuridaceae (Lacandonia schizmatica and L. braziliana) in which the stamens are centred and surrounded by the pistils; in Hydatellaceae the resulting 'flowers' may instead represent condensed inflorescences or non-flowers. [5]
These diminutive, superficially moss-like, aquatic plants are the closest living relatives of a clade comprising two closely related water-lily families Nymphaeaceae and Cabombaceae. [6] Together, these three families compose the order Nymphaeales in the APG III system of flowering plant classification. Trithuria (Hydatellaceae) diverged from the rest of Nymphaeales soon after Nymphaeales diverged from its sister taxon, although the crown clade evolved relatively recently, in the early Miocene (~19 Ma; [7] ). The order as a whole is the sister group of all flowering plants except Amborellales.
Trithuria exhibits a remarkable similarity to Centrolepis and species of both genera were mistaken for members of the other genus. [8]
The genus TrithuriaHook.f. was described by Joseph Dalton Hooker in 1858 [3] [9] with the type species Trithuria submersaHook.f. [3] It has two synonyms: In 1888 the genus JuncellaF.Muell. ex Hieron. was described [3] without a type designation [10] by Georg Hans Emmo Wolfgang Hieronymus based on previous work by Ferdinand von Mueller. [3] Mueller had invalidly published the nomen invalidum and nomen nudum Juncella tasmanicaF.Muell. in 1854. [11] [12] Juncella is a nomen illegitimum. [3] In 1904 the genus HydatellaDiels was described by Friedrich Ludwig Emil Diels [13] without a type designation, [14] but the lectotype Hydatella australisDiels. has been designated in 2008. [3] The genus Hydatella was synonymised with Trithuria in 2008. [3]
Trithuria was initially placed in the family Centrolepidaceae Endl. [15] (now synonymous with Restionaceae R.Br.), [16] which is placed in the order Poales Small [17] but it was separated as its own family Hydatellaceae U.Hamann by Ulrich Hamann in 1976 [18] [13] [19] with HydatellaDiels as the type genus. Upon its separation, Hamann stated the new families affinity or placement were still obscure. [13] The correct placement of the family became apparent in 2007, when it was identified as a basal angiosperm lineage. [15] The family Hydatellaceae is now placed in the order Nymphaeales Salisb. ex Bercht. & J. Presl.. [20] Alternatively, it is placed in a separate order Hydatellales Cronquist ex Reveal & Doweld validly published by James Lauritz Reveal and Alexander Borissowitsch Doweld in 1999 based on previous work by Arthur Cronquist (see the Cronquist system). [21] [22] This is however not widely accepted, as the order Hydatellales is mostly treated as a synonym of Nymphaeales. [20] [23] [24] [25]
Phylogeny of Trithuria [26] [27] | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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The generic name Trithuria is derived from the Greek words τρεις treis meaning "three", and θυρις thyris meaning "window". It references the dehiscence of the capsule fruit. [28] [29]
The diploid chromosome count of Trithuria inconspicua subsp. inconspicua is 2n = c. 24. The diploid chromosome count of Trithuria submersa is 2n = 56. [30] The diploid chromosome count of the tetraploid species Trithuria konkanensis 2n = 40. [31] The diploid chromosome count of Trithuria australis is 2n = 14. [32]
The IUCN conservation status of Trithuria lanterna is Least Concern (LC). [33] Trithuria inconspicua is critically endangered. [34]
The Nymphaeales are an order of flowering plants, consisting of three families of aquatic plants, the Hydatellaceae, the Cabombaceae, and the Nymphaeaceae. It is one of the three orders of basal angiosperms, an early-diverging grade of flowering plants. At least 10 morphological characters unite the Nymphaeales. One of the traits is the absence of a vascular cambium, which is required to produce both xylem (wood) and phloem, which therefore are missing. Molecular synapomorphies are also known.
The Cabombaceae are a family of aquatic, herbaceous flowering plants. A common name for its species is water shield. The family is recognised as distinct in the Angiosperm Phylogeny Group IV system (2016). The family consists of two genera of aquatic plants, Brasenia and Cabomba, totalling six species.
Hydatellaceae are a family of small, aquatic flowering plants. The family consists of tiny, relatively simple plants occurring in Australasia and India. It was formerly considered to be related to the grasses and sedges, but has been reassigned to the order Nymphaeales as a result of DNA and morphological analyses showing that it represents one of the earliest groups to split off in flowering-plant phylogeny, rather than having a close relationship to monocots, which it bears a superficial resemblance to due to convergent evolution. The family includes only the genus Trithuria, which has at least 13 species, although species diversity in the family has probably been substantially underestimated.
Barclaya is a genus of six species of flowering plants of the family Nymphaeaceae. Barclaya are aquatic plants native to tropical Asia. The genus was named in honour of the American-born English brewer and patron of science Robert Barclay.
Trithuria inconspicua is a small aquatic herb of the family Hydatellaceae that is only found in New Zealand.
Terry Desmond Macfarlane is a botanist and taxonomist, who has worked in both Australia and Peru. A senior research scientist at the Western Australian Herbarium, Macfarlane is associate editor of its journal Nuytsia and currently collaborates with researchers across Australia and in Canada, Germany, New Zealand, Russia, Spain and United Kingdom. He was also involved in the development of FloraBase, the Western Australian flora database.
Trithuria austinensis is a species of aquatic plant in the family Hydatellaceae endemic to Western Australia.
Trithuria australis is a species of aquatic plant in the family Hydatellaceae endemic to Western Australia.
Trithuria bibracteata is a species of aquatic plant in the family Hydatellaceae endemic to Western Australia.
Trithuria cookeana is a species of aquatic plant in the family Hydatellaceae endemic to the Northern Territory, Australia.
Trithuria cowieana is a species of aquatic plant in the family Hydatellaceae endemic to the Northern Territory, Australia.
Trithuria filamentosa is a species of aquatic plant in the family Hydatellaceae endemic to Tasmania, Australia.
Trithuria fitzgeraldii is a species of aquatic plant in the family Hydatellaceae endemic to Western Australia.
Trithuria konkanensis is a species of aquatic plant in the family Hydatellaceae endemic to India.
Trithuria lanterna is a species of plant in the family Hydatellaceae endemic to Australia.
Trithuria occidentalis is a species of plant in the family Hydatellaceae endemic to Western Australia.
Trithuria polybracteata is a species of plant in the family Hydatellaceae endemic to Western Australia.
Trithuria submersa is a species of plant in the family Hydatellaceae endemic to the Australian states New South Wales, South Australia, Tasmania, Victoria, and Western Australia.
Trithuria inconspicua subsp. brevistyla is a subspecies of Trithuria inconspicua in the family Hydatellaceae endemic to the South Island of New Zealand.
Nymphaea ondinea subsp. petaloidea is a subspecies of Nymphaea ondinea native to the Northern Territory, and Western Australia.
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