The rainforest genus Gossia N.Snow & Guymer (Myrtaceae) occurs in Australia, Melanesia and Malesia, and is capable of hyperaccumulating the heavy metal manganese (Mn). Here, we used nuclear ribosomal and plastid spacer DNA-sequence data to reconstruct the phylogeny of 19 Australian species of Gossia and eight New Caledonian taxa. Our results indicated that the relationship between Gossia and Austromyrtus (Nied.) Burret is not fully resolved, and most Australian species were supported as monophyletic. Non-monophyly might be related to incomplete lineage sorting or inaccurate taxonomic classification. Bark type appears to be a morphological synapomorphy separating two groups of species, with more recently derived lineages having smooth and mottled ‘python’ bark. New Caledonian species were well resolved in a single clade, but were not the first diverging Gossia lineage, calling into doubt the results of a recent study that found Zealandia as the ancestral area of tribe Myrteae. Within Australia, the evolution of multiple clades has probably been driven by well-known biogeographic barriers. Some species with more widespread distributions have been able to cross these barriers by having a wide range of soil-substrate tolerances. Novel Mn-hyperaccumulating species were identified, and, although Mn hyperaccumulation was not strongly correlated with phylogenetic position, there appeared to be some difference in accumulation levels among clades. Our study is the first detailed phylogenetic investigation of Gossia and will serve as a reference for future studies seeking to understand the origin and extent of hyperaccumulation within the Myrteae and Myrtaceae more broadly.

Phylogenetic relationships in Calochilus (∼30 species) were inferred based on a supermatrix of 81 loci including 22 species. To examine the spatio-temporal evolution of Calochilus, divergence-time estimations were conducted within a Bayesian framework using an uncorrelated relaxed molecular-clock model, followed by maximum-likelihood ancestral-range reconstructions comparing four biogeographic models. To trace the evolution of key floral and vegetative characters, maximum-likelihood ancestral-character reconstructions were carried out. The stem age of Calochilus was dated to ∼12.0 million years ago in the mid-Miocene. Divergence of Calochilus into a tropical and a temperate clade was inferred to have occurred ∼7.6 million years ago in the late Miocene. Northern Australia was reconstructed as the ancestral area of the tropical clade and the Euronotian region for the temperate clade. Range expansions from Australia to other Australasian regions, such as New Zealand and New Guinea, were inferred to have occurred only in recent geological times, commencing in the Pleistocene. The infrageneric classification for Calochilus was revised, erecting two subgenera, subgenus Calochilus and subgenus Tropichilus subgen. nov. Section Calochilus Szlach. was recircumscribed, and sect. Abrochilus sect. nov., and section Placochilus sect. nov. were erected. Identification keys to subgenera and sections and a taxonomic synopsis of the genus are provided.

The genus Elaeocarpus is the largest genus in the family Elaeocarpaceae, comprising more than 350 species of trees and shrubs with a mainly Indo-Pacific distribution. Approximately 28 species in the genus, including nine species from Australia, are known to possess ruminate endosperm. To provide a basis for understanding fruit development and endosperm rumination in the genus and, therefore, its taxonomic and evolutionary significance, we studied the fruit anatomy of Elaeocarpus ruminatus F.Muell. at different developmental phases (petal-fall to maturity). We found lignin in pericarp and ovary wall tissues in the earliest stages of development. In contrast, endosperm rumination occurs only after fruits have fully expanded, and becomes more pronounced as fruits ripen. Its phylogenetic distribution suggests that ruminate endosperm is a derived, albeit homoplasious character in Elaeocarpus. Comparative studies on related species will be instructive in determining the utility of ruminate endosperm for informing infra-generic taxonomy of the genus, and gaining insight into its adaptive significance.

Twenty-nine taxa of Eriocaulon L. are recorded in this synopsis of the genus for the region of New Guinea. A key to the New Guinea species is provided. The widespread E. cinereum R.Br. is not recorded for New Guinea but is included in the key. Eriocaulon brevipedunculatum var. longipes Moldenke is determined as a synonym of E. novoguineense P.Royen. Issues of lectotypification are discussed for E. echinulatum Mart. (syntypes identified), E. hamiltonianum Mart., E. hookerianum Stapf, E. nepalense var. luzulifolium (Mart.) Praj. & J.Parn., E. truncatum Buch.-Ham. ex Mart. Species with extra New Guinea distributions are E. australe R.Br., E. depressum R.Br. ex Sm., E. echinulatum, E. hamiltonianum, E. hookerianum, E. nepalense var. luzulifolium, E. setaceum L., E. sexangulare L., E. truncatum, E. willdenovianum Moldenke and E. zollingerianum Körn. A high level of endemism is recorded, particularly in the alpine zone.

Two new species of Plectranthus L’Hér. are described from tropical Queensland. Both Plectranthus laxus T.C.Wilson & P.I.Forst. and P. wallamanensis T.C.Wilson & P.I.Forst. are perennial suffrutescent shrubs found in open, exposed rocky habitats in the Wet Tropics bioregion. Both species are illustrated and notes on habitat, distribution, affinities and conservation status are provided. A revised key for Plectranthus in Queensland and the Australian tropics is presented.

The New Caledonian biodiversity hotspot contains many micro-hotspots that exhibit high plant micro-endemism, and that are facing different types and intensities of threats. The Belep archipelago, and especially Île Art, with 24 and 21 respective narrowly endemic species (1 Extinct, 21 Critically Endangered and 2 Endangered), should be considered as the most sensitive micro-hotspot of plant diversity in New Caledonia because of the high anthropogenic threat of fire. Nano-hotspots could also be defined for the low forest remnants of the southern and northern plateaus of Île Art. With an average rate of more than one new species described for New Caledonia each month since January 2000 and five new endemics for the Belep archipelago since 2009, the state of knowledge of the flora is steadily improving. The present account of eight new species from Île Art (Bocquillonia montrouzieri Gâteblé & McPherson, Cleidion artense Gâteblé & McPherson, Endiandra artensis Munzinger & McPherson, Eugenia belepiana J.W.Dawson ex N.Snow, Eugenia insulartensis J.W.Dawson ex N.Snow, Macaranga latebrosa Gâteblé & McPherson, Planchonella serpentinicola Swenson & Munzinger and Psychotria neodouarrei Barrabé & A.Martini) further demonstrates the need both to recognise the Belep Islands as a major New Caledonian micro-hotspot and to formulate concrete conservation programs for the archipelago.

The new species, Tecomanthe burungu Zich & A.J.Ford (Bignoniaceae) from the Wet Tropics bioregion of north-eastern Queensland is described, illustrated and differentiated from similar and closely related taxa.

Two additional species of the liverwort genus Chiastocaulon Carl, namely, C. fasciculatum M.A.M.Renner sp. nov. and C. pachycephalum (De Not.) Herzog, are reported from two mountain tops in the north of the Queensland Wet Tropics Bioregion, namely, Mount Finnigan and Thornton Peak. Given the recent completion of a revision for Chiastocaulon in Australia, the new species provides another cogent demonstration that the bryophyte flora of the Wet Tropics Bioregion is incompletely explored and documented. The new species Chiastocaulon fasciculatum is similar to C. dendroides (Nees) Carl, but can be distinguished by leaf shape and dentition, among other characters. The leaves of C. fasciculatum are ovate and bear two or three prominent equally sized teeth, and the ventral leaf margin bears two to eight smaller teeth, whereas the leaves of C. dendroides are elliptic and bear two unequally sized teeth, the postical of which is largest, and the ventral leaf margin is entire. Chiastocaulon fasciculatum, as far as currently known, is endemic to the Wet Tropics Bioregion. Chiastocaulon pachycephalum, of which the type is from Borneo, is reported for Australia for the first time from specimens collected on Mount Finnigan.

The Australian monsoon tropics are currently dominated by savanna and tropical woodland biomes that have arisen in response to a cooling and drying trend within the past ∼3 million years. It is expected that organisms well adapted to these conditions have expanded into available habitats, leading to the differentiation of populations and species across this landscape, a process that could be magnified by the presence of several biogeographic barriers. The broad-leaved paperbark (Melaleuca leucadendra (L.) L.) complex is one such group of plants, with 14 poorly morphologically differentiated species occupying large overlapping distributions across the region, and across several recognised biogeographic barriers. Using phylogenetic and network analyses of nuclear and plastid sequences, we tested species limits among currently described species within the complex and for phylogeographic structure within species across seven of these barriers. Overall, our data suggested patterns of differentiation among species consistent with the early to middle stages of incomplete lineage sorting, and evidence for an idiosyncratic cryptic response of species to biogeographic barriers. Unexpectedly, we found a deep molecular split across all species, broadly coinciding with the northern part of the Great Dividing Range, a feature not typically considered to be a barrier to dispersal. Our study has offered one of the first insights into the dynamics within and among widespread species across the north of Australia, suggesting considerably more geographic structure than was previously recognised.

Mycoheterotrophs, i.e. plants that acquire carbon from root-associated soil fungi, often have highly degraded plastomes, reflecting relaxed selective constraints on plastid genes following the loss of photosynthesis. Geosiris Baill. is the only mycoheterotrophic genus in Iridaceae and comprises two species in Madagascar and nearby islands, and a third recently discovered species in north-eastern Australia. Here, we characterise the plastomes of the Australian and one Madagascan species to compare patterns of plastome degradation in relation to autotrophic and other mycoheterotrophic taxa and investigate the evolutionary and biogeographical history of the genus in Iridaceae. Both examined species have lost approximately half their plastid-encoded genes and a small but significant reduction in purifying selection in retained non-photosynthetic genes was observed. Geosiris is confirmed as monophyletic, with initial divergence of the genus occurring c. 53 million years ago, and subsequent diversification occurring c. 30 million years ago. Africa (including Madagascar) is reconstructed as the most likely ancestral area of the genus, implying a major range-expansion event of one lineage to Australia after its divergence in the Oligocene. Our study has highlighted the dynamic evolutionary history of Geosiris, contributed to the characterisation of mycoheterotrophic plastomes, and furthered our understanding of plastome structure and function.