## 1 Introduction  
The semi-desert 'grassland' region of Australia's inner perimeter is in a transition zone between the sandy central Australian deserts and the tropical, subtropical, or temperate regions (Figure 1). In these semi-deserts, several species of _Eremophila_ are found in dwindling populations [1] adjacent to sandstone or shale ranges that, on rare occasions, channel rainwater to near exhausted water pans underlain by red or grey cracking clay, which is where some of the highest essential oil-yielding aromatic species can be found. Such species include the diploid specimens of _Eremophila longifolia_ ([PERSON] from Mutawintji National Park [2] and the myodesert-1-ene-yielding species _Eremophila dayana_. [PERSON] of the 'grey ranges' in south-west Queensland [3]. In contrast, other moderately aromatic species are sparsely distributed across the undulating slopes and plains of western New South Wales, the sand-to-clay dermosols on the flat plains of central west Queensland and north-west Western Australia. Human habitation of these arid parts is sparse, particularly outside of the lake regions (i.e., Menindee Lakes), where farming practices include cattle and sheep grazing. Due to populous wild goats, the native flora is under considerable pressure, with some common species in rapid decline as grazing continues to denude the landscape. The so called 'goat weed' is a classic example; _Eremophila latrobei_ [PERSON] is often found with only a few remaining leaves. In contrast, with the disappearance of indigenous foliage, opportunistic native species are rapidly finding a niche. Both _Eremophila sturti_ R.Br and _Eremophila mitchellii_ Benth. are becoming so common that they are regarded by some as a weed [4]. Previous phytochemical studies on the volatile organic compounds in species of _Eremophila_ demonstrate considerable intraspecific variability, particularly in _E. longifolia_[2; 5; 6]. Furthermore, aromatic timbers express completely different chemical profiles as compared to their leaves. To illustrate this, the aromatic timbers of _E. mitchellii_ were once regarded as a suitable alternative to the Australian sandalwood, _Santalum spicatum_ (R.Br) A.DC., producing a termite repellent essential oil comprised of eremophilones and other derivatives [7]. As a substitute, it came to be regarded with distaste and earned the colloquial name 'bastard sandalwood' and was discontinued [8]. Figure 1: Australian climate map; image taken from [[https://en.wikipedia.org/wiki/Deserts_of_Australia](https://en.wikipedia.org/wiki/Deserts_of_Australia)]([https://en.wikipedia.org/wiki/Deserts_of_Australia](https://en.wikipedia.org/wiki/Deserts_of_Australia)) (accessed on 15 January 2021). The etymology of the name _Eremophila_ is related to its persistence in arid regions. The name is an amalgamation of the Greek words 'eremos', which means desert, and 'philos', which means friend (or platonic love); hence, _Eremophila_ translates to 'desert loving'. It is also believed that the ephemeral nature of the arid landscapes is important in persuading the expression of secondary metabolites. Preliminary observations of the effects of persistent drought and the opposite, persistent watering, convey that cycles of wet and dry periods favour the expression of specialised metabolites, particularly the volatile organic compounds [2]. Theoretically, this character survives from an ancestral 'eremaeon' stock of diploid _Eremophila_[9], which developed polyploidy in response to pressures from prolonged drought during post-glaciation events some 75K years ago [10], leading to speciation events and creating the diversity that we know of today. _Eremophila_ is now comprised by more than 215 species [1], which include several that have not yet been described. Phytochemists have barely covered the full metabolite diversity of _Eremophila_.