Context Fewer than 10 plant species from Australia were known to hyperaccumulate metal(loid)s, despite metal-rich soils being widespread in Australia. By measuring herbarium specimens with non-destructive portable X-ray fluorescence spectroscopy (XRF) instrumentation their metal(loid)s concentrations can be determined, providing information that could be used to probe the evolution, biogeography, ecology, and physiology of plant species. Aims This study aimed to systematically measure herbarium specimens to obtain information on the prevailing concentrations of metal(loid)s in nearly 7000 plant specimens across seven plant families, and to link this data to an assessment of their spatial distribution. Methods The raw XRF spectrum of each herbarium specimen was processed using a new data-analysis pipeline recently validated for XRF data of herbarium specimens, to determine the concentrations of the first-row metal transition elements, and other detected elements. The collection localities of each of the herbarium specimens were plotted against rainfall and soil types to assess possible distributional patterns. Key results The results showed several newly discovered hyperaccumulator plant species, including 15 for manganese, two for nickel, three for cobalt, three for zinc, two for rare earth elements and one for selenium. Conclusions and implications Australia has more hyperaccumulator plant species than previously known and the XRF analysis of herbarium specimens is a powerful tool for their discovery. This research presents a new value proposition for the continued funding of herbarium collections in Australia and could initiate a range of research opportunities to use these data for future studies of plant evolution and adaptation.

Context Australia’s tropical montane cloud forests (TMCF) exhibit exceptional species richness and endemism. Determinants of regeneration via seed of these species are next to unknown, limiting our ability to quantify and project their vulnerability to climate change. The ratio of red to far-red light (R:FR) has been shown to influence seed germination of many tropical species. Aims We investigated germination of six previously unstudied TMCF species in relation to the presence or absence of light (light/dark) and light quality (R:FR). We hypothesised that increased R:FR would lead to increased germination and that small-seeded species would be more likely to have a light requirement and be less sensitive to R:FR compared to larger-seeded species. Methods Sunlight and polyester filters were used to create a gradient of R:FR ranging from 0.1 to 1.14. Seeds were also sown in constant darkness. Key results Across species we saw varying germination responses. Three of the four smallest-seeded species exhibited an absolute light requirement for germination and did not discriminate between different R:FR. Germination of the small-seeded TMCF endemic Dracophyllum increased exponentially with increasing R:FR. Germination of the largest-seeded species was inhibited by both low and high R:FR, and germination was higher in constant darkness than diurnal light/dark. All six species were able to germinate at remarkably low R:FR values. Conclusions Light affects seed germination of Australia’s TMCF plant species in a variety of ways. Implications The findings of this study provide insights into plant recruitment in situ, and the acclimation potential of these species under reduced R:FR predicted for the future.

Context As threatening processes continue to impact rare plant populations, the use of translocations is becoming increasingly frequent. The ultimate success of translocation, attaining long-term persistence, is determined by species’ ability to reproduce, recruit, and maintain levels of genetic diversity that permits the capacity to adapt to environmental change. Aims This study aimed to assess translocation success of Banksia brownii. Methods We compared genetic diversity, reproductive output and aspects of the mating system of a translocated population with four reference wild populations. Key results We found that the use of multiple source populations for the translocation resulted in levels of genetic diversity comparable to reference populations of high diversity. Reproductive output was highest in the translocated population and a positive relationship between plant size and number of flowers across all populations was evident. However, mating system analysis revealed a large difference in outcrossing rates between populations in different habitats despite common pollinators, with the translocated population having the highest rates of selfing. Conclusion Whilst genetic diversity and reproductive output were comparable or higher in the translocated population than in the reference populations, assessing translocation outcomes by these measures alone can potentially mask the longer-term erosion of genetic diversity through unfavourable patterns of mating. Implications We recommend using multiple metrics of reproductive, recruitment and genetic diversity to properly assess plant translocation success.

Context Asymbiotic germination is used for propagation of orchids and to assess seed viability. However, asymbiotic germination media remain undeveloped for Prasophyllum (Orchidaceae), a genus with 39 threatened species in southern Australia. Aims To develop asymbiotic germination and replate media for Prasophyllum, and determine whether survival of asymbiotically grown seedlings under nursery conditions is enhanced through the addition of a mycorrhizal fungus to potting media. Methods Using Prasophyllum frenchii as a model, we tested 81 asymbiotic germination medium combinations. The three best-performing media were then compared against four untested commercial media, with and without added coconut water and/or banana. The best-performing medium was trialled on 18 additional Prasophyllum species. Twenty-four replate media were then tested for their ability to support seedling development. We measured the survival of seedlings under nursery conditions with and without the addition of mycorrhizal Ceratobasidium fungus to potting media. Key results Low concentrations of minerals, auxins and cytokinins were necessary for asymbiotic germination of P. frenchii, although germination was highest overall on the commercial medium W9.5 with 5% coconut water. The most effective replate medium was W9 with 5% banana. However, survival of seedlings was 1.7%, 2 years after transferral to potting media in the nursery, regardless of the addition or absence of a mycorrhizal fungus. Conclusions Asymbiotic media can effectively germinate Prasophyllum seed, although deflasked seedlings have low survival rates. Implications Our media are broadly applicable to assess seed viability in Prasophyllum. However, poor survival of asymbiotically grown seedlings contrasts with recently published evidence of high seedling survival using symbiotic propagation methods, indicating that plants should be propagated symbiotically for conservation programs.

Context Silver banksia (Banksia marginata) savannas of south-eastern Australia were formerly widespread but are now largely cleared and fragmented, with small populations often showing recruitment limitation. Which may, in part, be due to seed predation by yellow-tailed black cockatoos (Zanda funerea), which have been observed foraging for seed. Aims The study aimed to investigate the impact of pre-dispersal seed predation by yellow-tailed black cockatoos on fruit crop between early development and seed release. Additionally, we wanted to assess seed fitness from partially damaged and discarded cones. Methods The study quantified silver banksia infructescence removal at four populations between early December and seed release in March. We also quantified seed mass and germinability of seeds from cones removed in December, February and March. Key results All populations experienced significant seed predation (>50%), with almost complete removal of cones from some populations. Early removal limits seed release from cones (only 18% of early removed follicles released seed). Further, early removal also significantly reduced seed mass and germination. Conclusions Pre-dispersal seed predation by cockatoos is likely to act as a strong filter for recruitment limitation in silver banksia, by negatively affecting annual seed crop size, seed fitness and germinability. Implications Our study showed the potential impact fragmentation can have on antagonistic plant–animal interactions. Small, isolated B. marginata populations are likely to continue to decline without active strategies to remedy seed predation such as large-scale restoration.

Context Germination is a vulnerable life stage for plants, therefore understanding the dynamics of seed ecology is essential to guiding management recommendations for highly invasive weeds. Aim We addressed the knowledge gap for how seeds contribute to the invasion process for European blackberry (Rubus anglocandicans), a threatening weed across the riparian ecosystems of south-western Australia. Methods We performed mechanical, chemical and thermal treatments on seeds to test for changes in germination success and conducted seed-burial trials to monitor seed viability over time in the soil seedbank. Key results In germination trials, freshly picked and frugivore egested seeds failed to germinate with the endocarp intact. With the endocarp removed, germination remained lower at 4–6 months compared with 10–28 months after collection, indicating a significant after-ripening period. Seeds in intact endocarps survived water immersion for more than 2 months, indicating an ability to survive winter flooding. Acid immersion did not improve germination. The germination success of seeds with endocarp removed increased linearly above 11°C, was greatest at 30°C and thereafter declined rapidly (no survival at 40°C). In a 5-year seed-burial trial, germination varied from 7.6 to 48.4% and was significantly lower closer to a river, and in areas where ‘blackberry decline’ syndrome was present. Conclusions While germination of seed without its pyrene coat occurred over a range of controlled conditions, the natural processes needed to break the pyrene remain unknown. Implications High germination success and the long-term survival of seeds in soil clarifies that the management of blackberry remains a difficult challenge in Australia.

Context Global environmental modification is placing increased demand on taxonomic resources, especially herbarium collections, which are being utilised for information and as biological resource material in ways never previously envisaged. This increased use of herbarium collections presents current and on-going management challenges. Aims To demonstrate, with two Australian studies, the essential role of herbarium collections in investigating long-term pollution; to emphasise the importance of on-going collecting for herbaria and make recommendations for future collection management. Methods Australian case studies of a long-term pollution problem are used to show how verified lichen and fungal taxa in Australian herbaria were crucial in identifying sources of air pollution over time. Key results Chemical and isotopic analyses of lead in samples from curated herbarium collections were used to reconstruct patterns of atmospheric lead deposition over 150 years in eastern Australia. This extended time series of samples facilitated documentation of the full cycle from natural background concentrations to the introduction and increasing usage of lead both in industry and motor vehicles, to the eventual discontinuation of its use in automotive fuel. In addition to demonstrating the value of regular, long-term sampling of selected taxa and potential applications to emerging environmental problems, the importance of strict protocols for destructive sampling and analysis of herbarium specimens, especially for older collections containing small quantities of material, has been highlighted. Conclusions Both the Australian and previous studies have identified a number of problems and potential challenges to maintaining and maximising the utilisation of finite herbarium resources for the future. While acknowledging that Australasian herbaria have well documented policies and protocols for studies that sample their collections, six recommendations are made, for future implementation as appropriate. Implications Current management strategies for finite reference collections are summarised and recommendations for the future include the following: repeated, ongoing collecting over broader areas; periodic re-collection of larger samples from select reference sites with detailed field data; preparation and storage of specimens under controlled environmental conditions, with minimal chemical pest control; utilisation of common widespread taxa for research; careful supervision of destructive sampling techniques to assess compounds present; and adequate funding to facilitate the digitisation of herbarium specimens to increase access and optimise use of curated collections.

Context Casuarina trees are extensively planted in the tropics for wood production and environmental services. The breeding program’s current focus is on developing hybrids that combine the specific characteristics of different species and are suitable for various planting environments and end uses. Aim Breeding programs aim to develop interspecific hybrids possessing desirable combinations of species-specific characters of Casuarina for increasing plantation productivity. Methods Controlled-pollination studies were conducted involving C. equisetifolia, C. junghuhniana and C. cristata to determine the possibility of hybridisation among them and to evaluate the hybridisation success rate in different cross-combinations. The pollen-tube growth in the pistil was studied to understand the role of pollen–pistil interactions in hybridisation success. Key result Fourteen cross-combinations of the three species resulted in 2–57% fruit set and 75.1–93.8% seed set. C. equisetifolia and C. junghuhniana hybridised reciprocally, whereas C. cristata hybridised with other species only as pollen parent. The larger flower size of C. cristata acted as a barrier preventing hybridisation with species having smaller-sized flowers. Variation in seed germination was large (3.6–91.3%), highest for C. junghuhniana and lowest for C. equisetifolia mothers. Fertilisation occurred 45 days after pollination in C. equisetifolia and C. junghuhniana and after 50 days in C. cristata. The ovary was immature at pollination and pollen tubes showed discontinuous growth in the pistil marked by periods of arrest for the ovules to develop. The stigma showed 3–5.7 pollen tubes, and invariably a single tube entered the ovary. The absence of major pre-fertilisation barriers but varying levels of hybridisation success indicates post-zygotic selection through embryo abortion. Conclusion Increasing the parental combinations of interspecific crosses where fruit set is limiting and pollinating more flowers per cross where germination is low may enhance hybridisation success. Implications The cross compatibility among different species of Casuarina provides scope to produce site and end-use specific hybrids to meet the commercial and livelihood needs.

Dr Beth Gott, a legendary Australian botanist, passed away recently aged 99. Her contribution to botanical research and teaching was exceptional, at Universities in Australia, the UK, the USA and Hong Kong. Her pioneering studies in the use of native plants by Australian aboriginal peoples are classics of the ethnobotanical literature.

The extent and abundance of Rytidosperma Steud. species in mixed woodland, forest and derived grassland was examined over a 15-year period following removal of long-term sheep grazing. Ground-layer vegetation in 73 permanent plots was surveyed five times between 2005 and 2020 in a 50-ha paddock on the southern tablelands of New South Wales. Sites were stratified over the slope positions and micro-habitats represented at the site. Of the 12 Rytidosperma species recorded, only R. pallidum was morphologically and ecologically distinct in the field. The remaining 11 species, termed ‘cryptic Rytidosperma’, were assessed using a novel sampling method developed for this group. Rytidosperma pallida was the only species strongly associated with sclerophyll forest habitat. The 11 other species varied in their habitat preferences but, as a group, were most dominant and persistent on upper slopes. Over the 15 years, the relative abundance of R. pilosum, R. erianthum, R. monticola, R. carphoides and R. caespitosum declined as annual exotics, native sub-shrubs and low-palatability graminoids became more dominant. But only one species (R. pilosum) significantly declined in overall frequency of presence (constancy) in the plots. The changes observed suggest that when pastoral land is converted to conservation management, reduced grazing pressure could affect the abundance of Rytidosperma species important to other species, such as the threatened moth Synemon plana.