Trithuria | |
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Trithuria submersa | |
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] All of the 13 formally characterized species of Trithuria are found in Australia, with the exception of T. inconspicua and T. konkanensis, which are found in 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 in the center of the flower while the pistils surround them; 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 Hydatella was subsumed into Trithuria as its members are phylogenetically nested in it. The family as a whole shares the following features (morphological synapomorphies [3] )
Phylogeny of Trithuria [10] [11] | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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The generic name Trithuria is composed of two parts: the Greek words treis meaning "three", and thyris meaning "window". It references the dehiscence of the fruit. [12] Specifically, it references the pericarp valves of some Trithuria species. [13]
The diploid chromosome count of Trithuria inconspicua subsp. inconspicua is 2n = c. 24. The diploid chromosome count of Trithuria submersa is 2n = 56. [13] The diploid chromosome count of the tetraploid species Trithuria konkanensis 2n = 40. [14] The diploid chromosome count of Trithuria australis is 2n = 14. [15]
Asparagales is an order of plants in modern classification systems such as the Angiosperm Phylogeny Group (APG) and the Angiosperm Phylogeny Web. The order takes its name from the type family Asparagaceae and is placed in the monocots amongst the lilioid monocots. The order has only recently been recognized in classification systems. It was first put forward by Huber in 1977 and later taken up in the Dahlgren system of 1985 and then the APG in 1998, 2003 and 2009. Before this, many of its families were assigned to the old order Liliales, a very large order containing almost all monocots with colorful tepals and lacking starch in their endosperm. DNA sequence analysis indicated that many of the taxa previously included in Liliales should actually be redistributed over three orders, Liliales, Asparagales, and Dioscoreales. The boundaries of the Asparagales and of its families have undergone a series of changes in recent years; future research may lead to further changes and ultimately greater stability. In the APG circumscription, Asparagales is the largest order of monocots with 14 families, 1,122 genera, and about 36,000 species.
A gametophyte is one of the two alternating multicellular phases in the life cycles of plants and algae. It is a haploid multicellular organism that develops from a haploid spore that has one set of chromosomes. The gametophyte is the sexual phase in the life cycle of plants and algae. It develops sex organs that produce gametes, haploid sex cells that participate in fertilization to form a diploid zygote which has a double set of chromosomes. Cell division of the zygote results in a new diploid multicellular organism, the second stage in the life cycle known as the sporophyte. The sporophyte can produce haploid spores by meiosis that on germination produce a new generation of gametophytes.
Flowering plants are plants that bear flowers and fruits, and form the clade Angiospermae, commonly called angiosperms. They include all forbs, grasses and grass-like plants, a vast majority of broad-leaved trees, shrubs and vines, and most aquatic plants. The term "angiosperm" is derived from the Greek words ἀγγεῖον /angeion and σπέρμα / sperma ('seed'), meaning that the seeds are enclosed within a fruit. They are by far the most diverse group of land plants with 64 orders, 416 families, approximately 13,000 known genera and 300,000 known species. Angiosperms were formerly called Magnoliophyta.
The Malpighiales comprise one of the largest orders of flowering plants, containing about 36 families and more than 16,000 species, about 7.8% of the eudicots. The order is very diverse, containing plants as different as the willow, violet, poinsettia, manchineel, rafflesia and coca plant, and are hard to recognize except with molecular phylogenetic evidence. It is not part of any of the classification systems based only on plant morphology. Molecular clock calculations estimate the origin of stem group Malpighiales at around 100 million years ago (Mya) and the origin of crown group Malpighiales at about 90 Mya.
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.
Nymphaeaceae is a family of flowering plants, commonly called water lilies. They live as rhizomatous aquatic herbs in temperate and tropical climates around the world. The family contains nine genera with about 70 known species. Water lilies are rooted in soil in bodies of water, with leaves and flowers floating on or emergent from the surface. Leaves are round, with a radial notch in Nymphaea and Nuphar, but fully circular in Victoria and Euryale.
In botany, apomixis is asexual reproduction without fertilization. Its etymology is Greek for "away from" + "mixing". This definition notably does not mention meiosis. Thus "normal asexual reproduction" of plants, such as propagation from cuttings or leaves, has never been considered to be apomixis, but replacement of the seed by a plantlet or replacement of the flower by bulbils were categorized as types of apomixis. Apomictically produced offspring are genetically identical to the parent plant.
Austrobaileyales is an order of flowering plants consisting of about 100 species of woody plants growing as trees, shrubs and lianas. The best-known species is Illicium verum, commonly known as star anise. The order belongs to the group of basal angiosperms, the ANA grade, which diverged earlier from the remaining flowering plants. Austrobaileyales is sister to all remaining extant angiosperms outside the ANA grade.
Pandanales, the pandans or screw-pines, is an order of flowering plants placed in the monocot clade in the Angiosperm Phylogeny Group and Angiosperm Phylogeny Web systems. Within the monocots Pandanales are grouped in the lilioid monocots where they are in a sister group relationship with the Dioscoreales. Historically the order has consisted of a number of different families in different systems but modern classification of the order is based primarily on molecular phylogenetics despite diverse morphology which previously placed many of the families in other groupings based on apparent similarity. Members of the order have a subtropical distribution and includes trees, shrubs, and vines as well as herbaceous plants. The order consists of 5 families, 36 genera and about 1,610 species.
Burmanniaceae is a family of flowering plants, consisting of 99 species of herbaceous plants in eight genera.
Brodiaeoideae are a monocot subfamily of flowering plants in the family Asparagaceae, order Asparagales. They have been treated as a separate family, Themidaceae. They are native to Central America and western North America, from British Columbia to Guatemala. The name of the subfamily is based on the type genus Brodiaea.
Asphodeloideae is a subfamily of the monocot family Asphodelaceae in the order Asparagales. It has previously been treated as a separate family, Asphodelaceae sensu stricto. The family Asphodelaceae has now been proposed to be a nomen conservandum, and the proposal has been recommended for ratification in 2017. In that case, Asphodelaceae will have priority over Xanthorrhoeaceae. This is reflected in the APG IV family lists.
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.
Lactoris fernandeziana is a flowering shrub endemic to the cloud forest of Masatierra — Robinson Crusoe Island, of the Juan Fernández Islands archipelago of Chile. It is the only extant species in the genus Lactoris.
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.
The basal angiosperms are the flowering plants which diverged from the lineage leading to most flowering plants. In particular, the most basal angiosperms were called the ANITA grade, which is made up of Amborella, Nymphaeales and Austrobaileyales.
Lilioid monocots is an informal name used for a grade of five monocot orders in which the majority of species have flowers with relatively large, coloured tepals. This characteristic is similar to that found in lilies ("lily-like"). Petaloid monocots refers to the flowers having tepals which all resemble petals (petaloid). The taxonomic terms Lilianae or Liliiflorae have also been applied to this assemblage at various times. From the early nineteenth century many of the species in this group of plants were put into a very broadly defined family, Liliaceae sensu lato or s.l.. These classification systems are still found in many books and other sources. Within the monocots the Liliaceae s.l. were distinguished from the Glumaceae.
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 Australia. 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. His favourite child is June.
Nanjinganthus dendrostyla is a fossil plant known from Early Jurassic sediments in China and proposed by Fu, et al. to represent a pre-Cretaceous angiosperm. The material consists of numerous compression fossils which bear a resemblance to flowers. The segments bear prominent ridges, suggesting veins, and a few specimens have a branched axis perpendicular to the segments, interpreted by Fu, et al. as a branched style. Beneath the putative perianth, Fu, et al. interpret the existence of ovules enclosed in ovaries, however, the preservation of this region of the structure is poor.