Prostanthera phylicifolia
Introduction '''''Prostanthera phylicifolia''''', commonly known as '''spiked mint-bush''', is a species of plant in the family Lamiaceae. It is an erect shrub with four-ridged branches, narrow egg-shaped to oval leaves and white or pale lilac-coloured flowers with purple and yellow spots.
Description ''Prostanthera phylicifolia'' is an erect, compact to spreading shrub that typically grows to a height of  and has four-ridged, slightly aromatic branches. The leaves are narrow egg-shaped to oval,  long and  wide on a petiole up to  long. The flowers are arranged near the ends of the branchlets with bracteoles  long at the base. The sepals are  long forming a tube  long with two lobes, the upper lobe  long. The petals are  long and white to pale lilac with purple spots inside the tube and yellow spots on the lower lobe.
Taxonomy ''Prostanthera phylicifolia'' was first formally described by Victorian Government botanist Ferdinand von Mueller in 1858 in his book ''Fragmenta Phytographiae Australiae'' from material collected from "Mt McFarlane" (now Macfarlane’s Lookout) near Omeo in northern Victoria and the “Maneroo” (present-day Monaro) region of New South Wales.George Bentham's 1870 revision of the genus ''Prostanthera'' broadened the species' circumscription, by citing specimens from the New England region of New South Wales and the Glass House Mountains, Queensland, in addition to the Victorian type locality. Bentham’s broad circumscription subsequently caused taxonomic confusion, and populations from northern New South Wales and southern Queensland were variously identified as either ''P. phylicifolia'' or ''P. scutellarioides'', despite considerable morphological differences between them. Molecular phylogenetic studies later confirmed Bentham's circumscription as erroneous, demonstrating that ''P. phylicifolia'' is restricted to localities cited in the original description, while populations from northern New South Wales and Queensland are more closely allied to ''P. scutellarioides''. The species was lectotypified in 2023 to restrict application of the name ''P. phylicifolia'' to populations in southern New South Wales and Victoria, as described in Mueller's original description.
Evolutionary relationships Molecular studies have demonstrated that ''P. phylicifolia'' is closely related to ''Prostanthera gilesii'' and ''Prostanthera volucris'', the latter not a species accepted by the Australian Plant Census or by Plants of the World Online as of September 2023.
Distribution and habitat This species occurs on hillsides and granite outcrops in heath and woodland in south-eastern New South Wales, the Australian Capital Territory and north-eastern Victoria.
Use in horticulture ''Prostanthera'' 'Poorinda Snow Queen' and 'Poorinda Ballerina', hybrid crosses of ''P. lasianthos'' and ''P. phylicifolia'', are cultivated.
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