Hydatellaceae

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Hydatellaceae
Botanische Jahrbucher fur Systematik, Pflanzengeschichte und Pflanzengeographie (1904) (20402793025).jpg
Botanical illustration of Trithuria australis from 1904
Scientific classification OOjs UI icon edit-ltr.svg
Kingdom: Plantae
Clade: Tracheophytes
Clade: Angiosperms
Order: Nymphaeales
Family: Hydatellaceae
U.Hamann [1] [2]
Genera [3]

Trithuria Hook.f.

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 (order Poales), 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. [4] The family includes only the genus Trithuria , which has at least 13 species, although species diversity in the family has probably been substantially underestimated. [5]

Contents

Description

Trithuria submersa Trithuria submersa - Flickr - Kevin Thiele.jpg
Trithuria submersa
Trithuria inconspicua Trithuria inconspicua iNat2.jpg
Trithuria inconspicua

Plants are submerged and emergent aquatic plants, rooted in the substrate below the water. They are tiny plants, just a few cm tall. Most species are ephemeral aquatics that flower in vernal pools when the water draws down, but several species are submerged perennials found in shallow lakes. The simple leaves are concentrated basally around a short stem. Individual species are cosexual (with several types of hermaphroditic conditions) or dioecious, and are either wind-pollinated (anemophilous) or self-pollinating (autogamous). Two predominantly apomictic species are also known. [6] Flower-like reproductive units are composed of small collections of minute stamen- and/or pistil-like structures that may each represent very reduced individual flower, so that the reproductive units may be pseudanthia. The non-fleshy fruits are follicles or achenes. [2]

Taxonomy

Trithuria submersa, fruiting Trithuria submersa in fruit.jpg
Trithuria submersa , fruiting

The family was for many years assumed to be a close relative of the grasses and sedges and was even sometimes lumped under the poalean family Centrolepidaceae. Even as recently as 2003, the APG II system assigned Hydatellaceae to the grass order Poales in the commelinid monocots. However, research based on DNA sequences and morphology by Saarela et al. indicates that Hydatellaceae is the living sister group of the water lilies (Nymphaeaceae and Cabombaceae) and thus represents one of the most ancient lineages of flowering plants. [7] Developers of earlier classifications were misled by the apparently reduced vegetative and reproductive morphology of these plants. As aquatic herbs, Hydatellaceae have environmental adaptations leading to derived characteristics that create a morphological similarity to the more distant taxon. Careful reanalysis of their morphological traits and comparisons with other so-called 'basal' angiosperms have supported this "dramatic taxonomic adjustment". [8] [9] This realignment is now recognized in the APG III and APG IV systems of classification. [1] [10]

The family now includes only the genus Trithuria Hook.f., which in 2008 was re-defined to include the genus HydatellaDiels. The type species is Trithuria submersaHook.f. [11]

Related Research Articles

<span class="mw-page-title-main">Nymphaeales</span> Order of flowering plants

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.

<span class="mw-page-title-main">Pandanales</span> Order of monocot flowering plants

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.

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

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.

<i>Trithuria</i> Genus of aquatic plants

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. All 13 described species of Trithuria are found in Australia, with the exception of T. inconspicua and T. konkanensis, from New Zealand and India respectively. 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 in which the stamens are centred and surrounded by the pistils; in Hydatellaceae the resulting 'flowers' may instead represent condensed inflorescences or non-flowers.

<span class="mw-page-title-main">Basal angiosperms</span> Descendants of most extant flowering plants

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.

<i>Maundia</i> Genus of flowering plants

Maundia is a genus of alismatid monocots, described in 1858. Maundia was formerly included in the family Juncaginaceae but is now considered to form a family of its own under the name Maundiaceae. It contains only one known species, Maundia triglochinoides, endemic to Australia.

<i>Trithuria inconspicua</i> Species of aquatic plant

Trithuria inconspicua is a small aquatic herb of the family Hydatellaceae that is only found in New Zealand.

<i>Trithuria austinensis</i> Species of aquatic plant

Trithuria austinensis is a species of aquatic plant in the family Hydatellaceae endemic to Western Australia.

<i>Trithuria australis</i> Species of aquatic plant

Trithuria australis is a species of aquatic plant in the family Hydatellaceae endemic to Western Australia.

<i>Trithuria bibracteata</i> Species of aquatic plant

Trithuria bibracteata is a species of aquatic plant in the family Hydatellaceae endemic to Western Australia.

<i>Trithuria cookeana</i> Species of aquatic plant

Trithuria cookeana is a species of aquatic plant in the family Hydatellaceae endemic to the Northern Territory, Australia.

<i>Trithuria cowieana</i> Species of aquatic plant

Trithuria cowieana is a species of aquatic plant in the family Hydatellaceae endemic to the Northern Territory, Australia.

<i>Trithuria filamentosa</i> Species of aquatic plant

Trithuria filamentosa is a species of aquatic plant in the family Hydatellaceae endemic to Tasmania, Australia.

<i>Trithuria fitzgeraldii</i> Species of aquatic plant

Trithuria fitzgeraldii is a species of aquatic plant in the family Hydatellaceae endemic to Western Australia.

<i>Trithuria konkanensis</i> Species of aquatic plant

Trithuria konkanensis is a species of aquatic plant in the family Hydatellaceae endemic to India.

<i>Trithuria lanterna</i> Species of aquatic plant

Trithuria lanterna is a species of plant in the family Hydatellaceae endemic to Australia.

<i>Trithuria occidentalis</i> Species of aquatic plant

Trithuria occidentalis is a species of plant in the family Hydatellaceae endemic to Western Australia.

<i>Trithuria polybracteata</i> Species of aquatic plant

Trithuria polybracteata is a species of plant in the family Hydatellaceae endemic to Western Australia.

<i>Trithuria submersa</i> Species of aquatic plant

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.

<i>Trithuria inconspicua <span style="font-style:normal;">subsp.</span> brevistyla</i> Species of aquatic plant

Trithuria inconspicua subsp. brevistyla is a subspecies of Trithuria inconspicua in the family Hydatellaceae endemic to the South Island of New Zealand.

References

  1. 1 2 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 (2): 105–121. doi: 10.1111/j.1095-8339.2009.00996.x . hdl: 10654/18083 .
  2. 1 2 Macfarlane, T.D.; Watson, L. & Marchant, N.G., eds. (2000). "Hydatellaceae U Hamann". FloraBase: Flora of Western Australian. Archived from the original on 14 July 2007. Retrieved 15 November 2013.
  3. ↑ "Hydatellaceae U.Hamann". Plants of the World Online . Royal Botanic Gardens, Kew . Retrieved 26 July 2023.
  4. ↑ Sokoloff, Dmitry D.; Marques, Isabel; Macfarlane, Terry D.; Remizowa, Margarita V.; Lam, Vivienne K.Y.; Pellicer, Jaume; Hidalgo, Oriane; Rudall, Paula J.; Graham, Sean W. (14 April 2019). "Cryptic species in an ancient flowering‐plant lineage (Hydatellaceae, Nymphaeales) revealed by molecular and micromorphological data". Taxon. 68. Wiley: 1–19. doi: 10.1002/tax.12026 . ISSN   0040-0262.
  5. ↑ Smissen, Rob D.; Ford, Kerry A.; Champion, Paul D.; Heenan, Peter B. (2019). "Genetic variation in Trithuria inconspicua and T. filamentosa (Hydatellaceae): a new subspecies and a hypothesis of apomixis arising within a predominantly selfing lineage". Australian Systematic Botany. CSIRO Publishing. doi:10.1071/sb18013. ISSN   1030-1887. S2CID   91261563.
  6. ↑ Saarela, Jeffery M.; Rai, Hardeep S.; Doyle, James A.; Endress, Peter K.; Mathews, Sarah; Marchant, Adam D.; Briggs, Barbara G. & Graham, Sean W. (2007). "Hydatellaceae identified as a new branch near the base of the angiosperm phylogenetic tree". Nature. 446 (7133): 312–315. Bibcode:2007Natur.446..312S. doi:10.1038/nature05612. PMID   17361182. S2CID   4415881.
  7. ↑ Rudall, Paula J.; Sokoloff, Dmitry D.; Remizowa, Margarita V.; Conran, John G.; Davis, Jerrold I.; Macfarlane, Terry D. & Stevenson, Dennis W. (2007). "Morphology of Hydatellaceae, an anomalous aquatic family recently recognized as an early-divergent angiosperm lineage". American Journal of Botany. 94 (7): 1073–1092. doi:10.3732/ajb.94.7.1073. hdl: 2440/44423 . PMID   21636477. S2CID   10405562.
  8. ↑ Friis, Else Marie; Crane, Peter R. & Pederses, Kaj Raunsgaard (2011). Early Flowers and Angiosperm Evolution. Cambridge University Press. ISBN   978-1-139-12392-1.
  9. ↑ 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.
  10. ↑ Sokoloff, Dmitry D.; Remizowa, Terry D. Macfarlane, Paula J. Rudall, Margarita V.; Macfarlane, Terry D. & Rudall, Paula J. (2008). "Classification of the early-divergent angiosperm family Hydatellaceae: one genus instead of two, four new species and sexual dimorphism in dioecious taxa" (PDF). Taxon. 57: 179–200.{{cite journal}}: CS1 maint: multiple names: authors list (link)
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