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
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 with 12 species (Christenhusz ">
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
Centrolepidaceae . Even as recently as 2003, the APG II system
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 (
Cabombaceae ) and thus
represents one of the most ancient lineages of flowering plants.
Developers of earlier classifications were misled by the apparently
reduced vegetative and reproductive morphology of these plants. As
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". This realignment is now recognized
in the APG III and APG IV systems of classification.
The family now includes only the genus
Trithuria , which in 2008 was
re-defined to include the genus Hydatella.
* ^ 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 .
* ^ A B Macfarlane, T.D.; Watson, L. & Marchant, N.G., eds. (2000).
Hydatellaceae U Hamann". FloraBase: Flora of Western Australian.
* ^ 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 identified as a new branch
near the base of the angiosperm phylogenetic tree". Nature. 446:
312–315. PMID 17361182 . doi :10.1038/nature05612 .
* ^ 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. PMID 21636477 . doi
* ^ 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. ISSN 0024-4074 . doi :10.1111/boj.12385 .
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 )