The APG III system places the order within theeurosids; this is corroborated by the placement of the Myrtales in the Malvid clade by theOne Thousand Plant Transcriptomes Initiative.[3]
Myrtales are placed as a sister to theeurosids IIclade as of the publishing of theEucalyptus grandis genome in June 2014.[4]
TheCronquist system gives essentially the same composition, except theVochysiaceae are removed to the orderPolygalales, and theThymelaeaceae are included. The familiesSonneratiaceae,Trapaceae, andPunicaceae are removed from the Lythraceae. In the classification system ofDahlgren the Myrtales were in thesuperorder 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 angiosperms, and notably in species in the order Myrtales.[5]
Myrtales is dated to around 89–99 million years ago (mya) inAustralasia; however, there is some contention as to that date, which was obtained usingnuclear DNA. When looking atchloroplast DNA, the myrtales' ancestor is, instead, considered to have evolved during the mid-Cretaceous period (100mya) inSoutheast Africa, rather than in Australasia.[6] Although the APG system classifies myrtales as within the eurosids, the recently published genome ofEucalyptus 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.[4]
^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,hdl:10654/18083
Schönenberger J, Conti E (February 2003). "Molecular phylogeny and floral evolution of Penaeaceae, Oliniaceae, Rhynchocalycaceae, and Alzateaceae (Myrtales)".American Journal of Botany.90 (2):293–309.doi:10.3732/ajb.90.2.293.PMID21659121.
