Trithuria inconspicua

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Trithuria inconspicua
Trithuria inconspicua iNat2.jpg
Trithuria inconspicua growing in fine silica sand
Status NZTCS NC.svg
Nationally Critical (NZ TCS) [1]
Scientific classification OOjs UI icon edit-ltr.svg
Kingdom: Plantae
Clade: Tracheophytes
Clade: Angiosperms
Order: Nymphaeales
Family: Hydatellaceae
Genus: Trithuria
Species:
T. inconspicua
Binomial name
Trithuria inconspicua
Cheeseman, 1906 [2]
Subspecies [3]
LocationNewZealand.svg
Distribution of Trithuria inconspicua
Synonyms [3]

Hydatella inconspicua (Cheeseman) Cheeseman

Trithuria inconspicua is a small aquatic herb of the family Hydatellaceae that is only found in New Zealand. [4] [5]

Contents

Description

T. inconspicua partially buried under sediment. Photo by Jeremy Rolfe Trithuria inconspicua lake.jpg
T. inconspicua partially buried under sediment. Photo by Jeremy Rolfe

Vegetative characteristics

Trithuria inconspicua is a small, 15–55 mm tall, aquatic, [1] perennial, [1] [5] rhizomatous [1] [6] herb with adventitious roots and glabrous, [1] linear-filiform, [7] 15–55 mm long, and 0.25–0.4 mm wide leaves. [1] The rhizome is up to 2 cm long, and up to 3 mm wide. [6]

Generative characteristics

It can be seen as either a monoicous, or in part as an exclusively female species. It can possess either bisexual, or unisexual reproductive units ("flowers"). [5] Female plants are more frequent, although male and bisexual individuals also occur. [7] [6] The male flowers consist of bright red 10 mm long filaments, whilst the female flowers are yellow-brown and contain 5-10 styles bunched at the apex. [1]

Cytology

The chloroplast genome is 165389 bp long. [8]

Taxonomy

It was published by Thomas Frederic Cheeseman in 1906. [2] [3] The lectotype specimen was collected by H. Carse in Lake Ngatu, New Zealand on the 1st of January 1902. [5] It is placed in Trithuria sect. Hydatella. [9]
It is divided into two subspecies, namely the autonymous subspecies Trithuria inconspicua subsp. inconspicua, which is found in coastal dune lakes in the North of North Island, New Zealand, and Trithuria inconspicua subsp. brevistyla K.A.Ford described in 2019, which is found in glacial lakes in the South of South Island, New Zealand. [7]

Etymology

The specific epithet inconspicua means inconspicous, not easily visible. [1] [10]

The first flowering plant?

Based on molecular data from a single plastid gene (rbcL)T. inconspicua was originally believed to a monocot. [11] However, a more recent study using multiple genetic loci, supported by a subsequent re-evaluation of morphological characteristics, now places T. inconspicua as a sister group with the water lilies (Nymphaeales). [12] This new placement of T. inconspicua means only a single lineage of flowering plant is thought to be older, that being the woody New Caledonian shrub Amborella trichopoda . [13]

The predominant view that Amborella represents the oldest flowering plant was recently challenged in a study by Goremykini et al (2013), [14] who showed that when highly variable sites were removed from the dataset, T. inconspicua was consistently identified as the oldest angiosperm lineage. This proposal has attracted criticism from Drew et al (2014), who argued that the basal placement of T. inconspicua is an artifact of the variable site filtering method used by Goremykini et al (2013). [15] One of the main reasons why people are interested in this question is that placing T. inconspicua at the base of the angiosperm lineage would suggest the first angiosperms were soft bodied aquatic plants, rather than a woody terrestrial plants like Amborella . These competing theories have been given the light hearted monikers "wet and wild" and "dark and disturbed". [15] [16] [17]

Conservation status

Trithuria inconspicua is seriously threatened [1] due to the competition by the introduced bladder wort ( Utricularia gibba ) as well as other fresh water weeds.

Ecology

It occurs in coastal dune lakes and glacial lakes [7] in shallow to 5–7 m deep waters. It grows in mud, sand, and gravel substrates. [1] The plants are often partly buried within the substrate. [7] [1]

Cultural significance

It has been chosen to be the New Zealand's Favourite Plant 2024. [18] [19]

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.

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

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.

<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.

<span class="mw-page-title-main">Mesangiospermae</span> One of two clades of flowering plants

Mesangiospermae is a clade of flowering plants (angiosperms) that contains about 99.95% of all angiosperm species. Mesangiosperms are therefore known as the core angiosperms, in contrast to the earlier-diverging species known as the basal angiosperms. Mesangiospermae includes about 350,000 species, while there are about 175 extant species of basal angiosperms.

<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 3 4 5 6 7 8 9 10 11 de Lange, P.J. (2024): Trithuria inconspicua Fact Sheet (content continuously updated). New Zealand Plant Conservation Network. https://www.nzpcn.org.nz/flora/species/trithuria-inconspicua/ (2024-11-13)
  2. 1 2 Cheeseman, T. F. (1906), Manual of the New Zealand Flora, New Zealand Government, p. 756, OCLC   688378960, Wikidata   Q5992016
  3. 1 2 3 "Trithuria inconspicua Cheeseman". Plants of the World Online . Royal Botanic Gardens, Kew . Retrieved 18 May 2022.
  4. ↑ Kew World Checklist of Selected Plant Families
  5. 1 2 3 4 Dmitry D. Sokoloff, Margarita V. Remizowa, Terry D. Macfarlane, and Paula J. Rudall. 2008. "Classification of the early-divergent angiosperm family Hydatellaceae: one genus instead of two, four new species and sexual dimorphism in dioecious taxa". Taxon57(1):179-200.
  6. 1 2 3 Pledge, David H. 1974. "Some Observations on Hydatella Inconspicua (Cheesem.) Cheesem. (Centrolepidaceae)." New Zealand Journal of Botany 12 (4): 559–61.
  7. 1 2 3 4 5 Smissen, R. D., Ford, K. A., Champion, P. D., & Heenan, P. 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, 32(1), 1-11.
  8. ↑ Gruenstaeudl, M., Nauheimer, L., & Borsch, T. (2017). Plastid genome structure and phylogenomics of Nymphaeales: conserved gene order and new insights into relationships. Plant systematics and evolution, 303, 1251-1270.
  9. ↑ Iles, W. J., Rudall, P. J., Sokoloff, D. D., Remizowa, M. V., Macfarlane, T. D., Logacheva, M. D., & Graham, S. W. (2012). Molecular phylogenetics of Hydatellaceae (Nymphaeales): Sexual‐system homoplasy and a new sectional classification. American Journal of Botany, 99(4), 663-676.
  10. ↑ Manaaki Whenua – Landcare Research. (n.d.-a). Trithuria inconspicua Cheeseman. Biota of New Zealand. Retrieved November 13, 2024, from https://biotanz.landcareresearch.co.nz/scientific-names/bb52b280-93f6-45d3-b434-ea6c4081e712
  11. ↑ Michelangeli, Fabian A., Jerrold I. Davis, and Dennis Wm Stevenson. 2003. "Phylogenetic Relationships among Poaceae and Related Families as Inferred from Morphology, Inversions in the Plastid Genome, and Sequence Data from the Mitochondrial and Plastid Genomes." American Journal of Botany 90 (1): 93–106.
  12. ↑ Saarela, Jeffery M., Hardeep S. Rai, James A. Doyle, Peter K. Endress, Sarah Mathews, Adam D. Marchant, Barbara G. Briggs, and Sean W. Graham. 2007. "Hydatellaceae Identified as a New Branch near the Base of the Angiosperm Phylogenetic Tree." Nature 446 (7133): 312–15.
  13. ↑ Friis, Else Marie, and Peter Crane. 2007. "Botany: New Home for Tiny Aquatics." Nature 446 (7133): 269–70.
  14. ↑ Goremykini, V.V.; Nikiforova, S.V.; Biggs, P.J.; Zhong, B. de Lange, P.; Martin, W.; Woetzel, S.; Atherton, R.A., McLenachan, T.; Lockhart, P.J. 2013: The evolutionary root of flowering plants. Systematic Biology61 (1) 50–61.
  15. 1 2 Drew, Bryan T., Brad R. Ruhfel, Stephen A. Smith, Michael J. Moore, Barbara G. Briggs, Matthew A. Gitzendanner, Pamela S. Soltis, and Douglas E. Soltis. 2014. "Another Look at the Root of the Angiosperms Reveals a Familiar Tale." Systematic Biology 63 (3): 368–82.
  16. ↑ Feild, Taylor S., Nan Crystal Arens, James A. Doyle, Todd E. Dawson, and Michael J. Donoghue. 2004. "Dark and Disturbed: A New Image of Early Angiosperm Ecology." Paleobiology 30 (1): 82–107.
  17. ↑ Coiffard, C., B. Gomez, and F. Thevenard. 2007. "Early Cretaceous Angiosperm Invasion of Western Europe and Major Environmental Changes." Annals of Botany 100 (3): 545–53.
  18. ↑ Critically endangered Northland lake plant voted NZ’s favourite plant 2024 - Northland Regional Council. (n.d.). Retrieved November 6, 2024, from https://www.nrc.govt.nz/news/2024/november/critically-endangered-northland-lake-plant-voted-nz-s-favourite-plant-2024/
  19. ↑ Degraaf, P. (2024, November 5). Ancient, inconspicuous plant voted New Zealand’s favourite. RNZ. https://www.rnz.co.nz/news/national/532934/ancient-inconspicuous-plant-voted-new-zealand-s-favourite
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