The Myrtales are an order of flowering plants placed as a sister to the eurosids II clade as of the publishing of the Eucalyptus grandis genome in June 2014.
The APG III system of classification for angiosperms still places it within the eurosids. This finding is corroborated by the placement of the Myrtales in the Malvid clade by the One Thousand Plant Transcriptomes Initiative. The following families are included as of APGIII:
The Cronquist system gives essentially the same composition, except the Vochysiaceae are removed to the order Polygalales, and the Thymelaeaceae are included. The families Sonneratiaceae, Trapaceae, and Punicaceae are removed from the Lythraceae. In the classification system of Dahlgren the Myrtales were in the superorder Myrtiflorae (also called Myrtanae). The APGIII system agrees with the older Cronquist circumscriptions of treating Psiloxylaceae and Heteropyxidaceae within Myrtaceae, and Memecyclaceae within Melastomataceae.
Ellagitannins are reported in dicotyledoneous angiospermes, and notably in species in the order Myrtales.
Myrtales is dated to have begun 89-99 million years ago (mya) in Australasia. There is some contention as to that date however, which was obtained using nuclear DNA. When looking at chloroplast DNA, the myrtales ancestor is instead considered to have evolved in the mid-Cretaceous period (100mya) in Southeast Africa, rather than in Australasia. Although the APG system classifies myrtales as within the eurosids, the recently published genome of Eucalyptus grandis places the order myrtales as a sister to the eurosids rather than inside them. The discrepancy is thought to have arisen due to the difference between using numerous taxa versus using various genes for constructing a phylogeny.
^ abAngiosperm 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
^Grattapaglia D, Vaillancourt RE, Shepherd M, Thumma BR, Foley W, Külheim C, Potts BM, Myburg AA (June 2012). "Progress in Myrtaceae genetics and genomics: Eucalyptus as the pivotal genus". Tree Genetics & Genomes. 8 (3): 463-508. doi:10.1007/s11295-012-0491-x.
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