Advances in high‐throughput, comprehensive small molecule analytical techniques have seen the development of the field of metabolomics. The coupling of mass spectrometry with high‐resolution chromatography provides extensive chemical profiles from complex biological extracts. These profiles include thousands of compounds linked to gene expression, and can be used as taxonomic characters. Studies have shown metabolite profiles to be taxon specific in a range of organisms, but few have investigated taxonomically problematic plant taxa. This study used a phenetic analysis of metabolite profiles to test taxonomic boundaries in the Olearia phlogopappa (Asteraceae) complex as delimited by morphological data. Metabolite profiles were generated from both field‐ and shade hous‐egrown material, using liquid chromatography‐mass spectrometry (LC‐MS). Aligned profiles of 51 samples from 12 taxa gave a final dataset of over 10,000 features. Multivariate analyses of field and shade house material gave congruent results, both confirming the distinctiveness of the morphologically defined species and subspecies in this complex. Metabolomics has great potential in alpha taxonomy, especially for testing the boundaries of closely related taxa where DNA sequence data has been uninformative.

Recent molecular work on Olearia s.l. has not supported current generic or sectional concepts, instead identifying two major lineages loosely based on distribution. Further work is required to adequately circumscribe Olearia s.s. The present study aimed to determine the monophyly of Australian stellate-haired species of Olearia. Using four molecular regions (ITS, psbA–trnH, rpl32–trnL and matK) sequenced from 27 species, Australian stellate-haired taxa were confirmed as monophyletic. Accordingly, Olearia section Asterotriche is redefined here to include only Australian species. This section is one of the few confirmed natural groups in Olearia. Section Asterotriche is closely associated with, but does not include, the type species of Olearia, O. tomentosa (J.C.Wendl.) DC. Given this close association to the type, section Asterotriche should be retained within Olearia, pending further research that would justify any future changes. This manuscript concludes with a monograph of section Asterotriche, in it six new subspecies are described and nine taxa are lectotypified.

A morphometric study of the Olearia phlogopappa species complex from throughout south-eastern Australia has confirmed species boundaries and resolved the infraspecific taxonomy of two species. It has shown O. phlogopappa (Labill.) DC., O. stellulata (Labill.) DC., O. lirata (Sims) Hutch., O. rugosa (F.Muell. ex W.Archer bis) Hutch. and O. brevipedunculata N.G.Walsh to be non-overlapping entities with unique morphological characters. O. stellulata is circumscribed to include only southern and western Tasmanian populations and those from the Otways and Wilsons Promontory in southern Victoria. O. rugosa is restricted to Victoria and a few isolated populations on Flinders Island and northern Tasmania. Four previously noted variants of O. rugosa from Victoria are here described as subspecies, along with the description of a fifth subspecies from northern Tasmania. Infraspecific boundaries of O. phlogopappa are here revised to include nine subspecies, six of which were previously included as varieties, and descriptions are made of three new subspecies.

The genus Melicytus (Violaceae), formerly regarded as comprising a single species, M. dentatus, in mainland Australia and Tasmania, is revised. We recognise M. dentatus, M. angustifolius subsp. angustifolius and M. angustifolius subsp. divaricatus following detailed herbarium and field studies, and morphological and molecular analyses. Full nomenclature is provided, and each species and subspecies is illustrated and mapped.