Myosotis australis is a species of flowering plant in the family Boraginaceae, native to New Zealand, Australia and New Guinea. Robert Brown described this species in 1810. Plants of this species of forget-me-not are perennial rosettes with ebracteate inflorescences and white or yellow corollas with stamens that are fully included in the corolla tube or sometimes partly protruded.
Taxonomy and etymology
Myosotis australis R.Br. is in the plant family Boraginaceae. The species was originally described by Robert Brown in his Prodromus florae Novae-Hollandiae et Insulae Van Diemen 1810.
The lectotype was collected by Robert Brown on the "banks of Paterson River" (New South Wales, Australia), is lodged at the herbarium of the Natural History Museum (BM 000939408), and was designated by Carlos Lehnebach.
Myosotis australis is morphologically most similar to other ebracteate-erect species from New Zealand, especially Myosotis saxatilis. Several morphological characters can be used to distinguish M. australis from M. saxatilis. The partially bracteate, distally non-bifurcating inflorescence in M. australis can help distinguish it from the obviously bifurcating, ebracteate inflorescence of M. saxatilis. In addition, M. australis has long internodes (>10 mm) between fruits at fruiting, whereas M. saxatilis has short internodes (<12 mm).
The species epithet australis is a Latin word that means south or southern, referring to its presence in Australia.
According to the latest taxonomic treatment, the following names are all synonyms of M. australis: Myosotis mooreana Lehnebach, M. lytteltonensis (Laing & A.Wall) de Lange (and M. australis var. lytteltonensis Laing & A.Wall;), and M. australis var. conspicua Cheeseman.
Two subspecies are recognized in the latest taxonomic treatment: Myosotis australis subsp. australis (native to Australia and New Zealand), and M. australis subsp. saruwagedica (endemic to New Guinea). The subspecies are allopatric, and can be distinguished from one another based on the presence of hooked hairs on the underside of the uppermost cauline leaves, length and length to width ratio of the rosette leaf blade, presence of stolons.
Phylogeny
Four individuals of M. australis, including two from Australia, one from New Guinea, and one from New Zealand, were included in a phylogenetic analyses of standard DNA sequencing markers (nuclear ribosomal DNA and chloroplast DNA regions). These same four individuals, plus five others from New Zealand (including one each identified as M. mooreana and M. lytteltonensis), were included in a subsequent phylogeny (two other New Zealand individuals identified as M. australis aff. were subsequently re-identified as other species).
In both studies, within the southern hemisphere lineage, the M. australis individuals were not monophyletic, but in general species relationships were not well resolved.