## 2 Results and Discussion
### Miscellaneous Eremophila by Endemic Location
#### 2.4.2 _Eremophila_ of the Murchison District, Western Australia  
The Murchison District of Western Australia is potentially the location of the ancestral stock of Australian _Eremophila_. It was put forward by [PERSON] that post glaciation aridity more than 75K years prior caused a significant die back of Australian species, restricting the _Eremophila_ genus to the Murchison District, from where it developed polyploidy and increased adaptability to recolonise the lands of the continent [9]. It was later speculated that Mutawintji NP of New South Wales may have also been an ancestral stock, since most of the tetraploid _E. longifolia_ of Australia follow terpenoid biosynthesis, which is a character of the diploids of Mutawintji NP, but not the Murchison diploids, which express only phenylpropanoids [2].  
A species in the Murchison District of Western Australia that is very similar to _E. gilesii_ is _E. foliosissima_, which was collected from the Sandstone airstrip. _Eremophila_ foliosissima produced an essential oil (Efo-57, Table 4) with a different profile of volatiles compared to _E. gilesii_, comprised by the monoterpenoid pinene isomers (\(\alpha/\beta\)) and the sesquiterpenes, elemol and eudesmol isomers.  
Three further essential oils in Table 4 were produced from _E. platycalyx_ (Epla-53, Epla-61, and Epla-62), which were sampled from the Murchison District of Western Australia and identified by [PERSON] (authority on _Eremophila_[1]) in email correspondence. It was communicated that _E. platycalyx_ is morphologically variable and may include variants that are not yet described.  
The monoterpenes in the hydrodistilled essential oils from _E. platycalyx_ include the pinene isomers, camphene, limonene and \(\beta\)-phellandrene (Table 4). Furthermore, like the sympatric species _E. foliosissima_, _E. platycalyx_ also expresses the eudesmol isomers. Lastly, farnesol is also evident in the essential oil profile, which as previously mentioned is a promoter of biofilm formation in bacteria. _Eremophila platycalyx_, was also studied by solvent extraction (Epla, Table 10) from a private garden specimen. The analysis of the solvent extract (Epla, Table 10) detected \(>90\%\) low vapour pressure components that are not driven into the essential oil in hydrodistillation. These components were not isolated or identified in the current study.  
A species that occurs in the Murchison District but is also widely distributed across Australia is _E. youngii_ (Eyo-345). This species gives a high-yielding monoterpenoid essential oil with 1,8-cineole as a major component. However, since this species has such a wide distribution it should be examined for cytogeographical and chemotypic variation, like _E. longifolia_, because it occurs in the Murchison District.  
Two of the species from the Murchison District expressed ngaione, dehydrodrongaione and significant relative abundances of unidentified furanosesquiterpenes that require isolation and elucidation in a future study. These two species were _E. laanii_ (Elaa) and _E. pterocarpa_ (Epte). As a side note, the two non-volatile furofuran lignans sesamin and aptosimon were also isolated from leaves of _E. pterocarpa_, and assigned against published spectra [52; 53]. Then, another two species expressed germacrene D, i.e., _E. spectabilis_ subsp. _brevis_ (EspB) and _E. recurura_ (Erec) (Tables 10 and 11, respectively). However, _E. recurura_ also expressed the uncommon sesquiterpene germacrene-D-4-ol, as well as eremoacetal. Eremoacetal was identified in only one other species, which is also endemic to Western Australia but restricted to southern parts, proximate to Kalgoorlie.