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Trithuria

Hydatellaceae
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
Nymphaeales
as a result of DNA and morphological analyses showing its closer affinity to basal angiosperms than to the order Poales, to which it bears a superficial resemblance. The family includes only the genus Trithuria
Trithuria
with 12 species (Christenhusz & Byng 2016 [3]). .

Contents

1 Description 2 Taxonomy 3 References 4 External links

Description[edit] The family consists of ten or more species with substantial variation among them.[4] Plants are submerged and emergent aquatic annuals, rooted in the substrate below the water. They are tiny (a few cm tall) and relatively simple. The simple leaves are concentrated basally around a short stem. The members of this plant family are monoecious or dioecious and are likely wind-pollinated (anemophilous), water-pollinated (hydrophilous) or self-pollinating (autogamous). 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[edit]

Trithuria
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
Hydatellaceae
to the grass order Poales
Poales
in the commelinid monocots. However, research based on DNA sequences and morphology by Saarela et al. indicates that Hydatellaceae
Hydatellaceae
is the living sister group of the water lilies ( Nymphaeaceae
Nymphaeaceae
and Cabombaceae) and thus represents one of the most ancient lineages of flowering plants.[4] Developers of earlier classifications were misled by the apparently reduced vegetative and reproductive morphology of these plants. As aquatic herbs, Hydatellaceae
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 basal angiosperms have supported this "dramatic taxonomic adjustment".[5][6] This realignment is now recognized in the APG III and APG IV systems of classification.[1][7] The family now includes only the genus Trithuria, which in 2008 was re-defined to include the genus Hydatella.[8] References[edit]

^ a b Angiosperm Phylogeny Group (2009). "An update of the Angiosperm Phylogeny Group classification for the orders and families of flowering plants: APG III" (PDF). Botanical Journal of the Linnean Society. 161 (2): 105–121. doi:10.1111/j.1095-8339.2009.00996.x. Retrieved 2013-06-26.  ^ a b Macfarlane, T.D.; Watson, L. & Marchant, N.G., eds. (2000). " Hydatellaceae
Hydatellaceae
U Hamann". FloraBase: Flora of Western Australian. Retrieved 2013-11-15.  ^ Christenhusz, M. J. M.; Byng, J. W. (2016). "The number of known plants species in the world and its annual increase". Phytotaxa. Magnolia Press. 261 (3): 201–217. doi:10.11646/phytotaxa.261.3.1.  ^ a b 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
Hydatellaceae
identified as a new branch near the base of the angiosperm phylogenetic tree". Nature. 446 (7133): 312–315. doi:10.1038/nature05612. PMID 17361182.  ^ 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. PMID 21636477.  ^ Friis, Else Marie; Crane, Peter R. & Pederses, Kaj Raunsgaard (2011). Early Flowers and Angiosperm Evolution. Cambridge University Press. ISBN 978-1-139-12392-1.  ^ Angiosperm Phylogeny Group (2016). "An update of the Angiosperm Phylogeny Group classification for the orders and families of flowering plants: APG IV" (PDF). Botanical Journal of the Linnean Society. 181 (1): 1–20. doi:10.1111/boj.12385. ISSN 0024-4074. CS1 maint: Uses authors parameter (link) ^ 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". Taxon. 57: 179–200. CS1 maint: Multiple names: authors list (link)

External links[edit]

Hydatellaceae
Hydatellaceae
in L. Watson and M.J. Dallwitz (1992 onwards). The families of flowering plants: descriptions, illustrations, identification, information retrieval. Version: 27 April 2006. https://web.archive.org/web/20060424062016/http://delta-intkey.com/ Hydatellaceae
Hydatellaceae
photographs Hydatella in western Australia Trithuria
Trithuria
in western Australia NCBI Taxonomy Browser links at CSDL Original paper recognising the family[permanent dead link]

Data related to Hydatellaceae
Hydatellaceae
at Wikispecies

Taxon identifiers

Wd: Q131515 EoL: 8222 EPPO: 1HYAF FloraBase: 22759 Fossilworks: 55816 GBIF: 8827 GRIN: 556 IPNI: 8-1 ITIS: 896685 NCBI: 178426 Tropicos: 42000358 Watson &

.