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">Asparagales</span> Order of monocot flowering plants

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.

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

The Dioscoreales are an order of monocotyledonous flowering plants, organized under modern classification systems, such as the Angiosperm Phylogeny Group or the Angiosperm Phylogeny Web. Among monocot plants, Dioscoreales are grouped with the lilioid monocots, wherein they are a sister group to the Pandanales. In total, the order Dioscoreales comprises three families, 22 genera and about 850 species.

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

The Poales are a large order of flowering plants in the monocotyledons, and includes families of plants such as the grasses, bromeliads, rushes and sedges. Sixteen plant families are currently recognized by botanists to be part of Poales.

<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.

Hydatellales is a botanical name for an order of flowering plants. In the Cronquist system, 1981, the name was used for an order placed in the subclass Commelinidae in class Liliopsida [=monocotyledons]. The order consisted of one family only:

<span class="mw-page-title-main">Monocotyledon</span> Clade of flowering plants

Monocotyledons, commonly referred to as monocots, are grass and grass-like flowering plants (angiosperms), the seeds of which typically contain only one embryonic leaf, or cotyledon. They constitute one of the major groups into which the flowering plants have traditionally been divided; the rest of the flowering plants have two cotyledons and are classified as dicotyledons, or dicots.

<i>Amborella</i> Species of shrub

Amborella is a monotypic genus of understory shrubs or small trees endemic to the main island, Grande Terre, of New Caledonia in the southwest Pacific Ocean. The genus is the only member of the family Amborellaceae and the order Amborellales and contains a single species, Amborella trichopoda. Amborella is of great interest to plant systematists because molecular phylogenetic analyses consistently place it as the sister group to all other flowering plants, meaning it was the earliest group to evolve separately from all other flowering plants.

<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">Petrosaviaceae</span> Family of flowering plants

Petrosaviaceae is a family of flowering plants belonging to a monotypic order, Petrosaviales. Petrosaviales are monocots, and are grouped within the lilioid monocots. Petrosaviales is a very small order composed of one family, two genera and four species accepted in 2016. Some species are photosynthetic (Japonolirion) and others are rare, leafless, chlorophyllous, mycoheterotrophic plants (Petrosavia). The family is found in low-light montane rainforests in Japan, China, Southeast Asia and Borneo. They are characterised by having bracteate racemes, pedicellate flowers, six persistent tepals, septal nectaries, three almost-distinct carpels, simultaneous microsporogenesis, monosulcate pollen, and follicular fruit.

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

Burmanniaceae is a family of flowering plants, consisting of 99 species of herbaceous plants in eight genera.

<span class="mw-page-title-main">Hemerocallidoideae</span> Subfamily of flowering plants

Hemerocallidoideae is a subfamily of flowering plants, part of the family Asphodelaceae sensu lato in the monocot order Asparagales according to the APG system of 2016. Earlier classification systems treated the group as a separate family, the Hemerocallidaceae. The name is derived from the generic name of the type genus, Hemerocallis. The largest genera in the group are Dianella, Hemerocallis (15), and Caesia (11).

<span class="mw-page-title-main">Asphodelaceae</span> Family of flowering plants in the order Asparagales

Asphodelaceae is a family of flowering plants in the order Asparagales. Such a family has been recognized by most taxonomists, but the circumscription has varied widely. In its current circumscription in the APG IV system, it includes about 40 genera and 900 known species. The type genus is Asphodelus.

<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.

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

Dasypogonaceae is a family of flowering plants based on the type genus Dasypogon, one that has traditionally not been commonly recognized by taxonomists; the plants it contains were usually included in the family Xanthorrhoeaceae. If valid, Dasypogonaceae includes four genera with 16 species. The family is endemic to Australia. The best known representative is Kingia australis.

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

Boryaceae is a family of highly drought-tolerant flowering plants native to Australia, placed in the order Asparagales of the monocots. The family includes two genera, with twelve species in total in Australia.

<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 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. 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 in the center of the flower while the pistils surround them; 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.

<span class="mw-page-title-main">Lilioid monocots</span> Grade of flowering plant orders, within Lilianae

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.

<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.

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 .
  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. Wiley. 68: 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)