Quantifying endangerment value: a promising tool to support curation decisions

Botanic garden collections are increasingly seeking to quantify and improve the value of their collections for science, horticulture, conservation and other uses. Quantifying the value of a collection depends on the mission of the institution. Many botanic gardens are prioritising the conservation of rare and threatened species towards preventing plant extinctions. In doing so, botanic gardens must make decisions about which plants should remain, be replaced or be added to their collections, and how to allocate staff and resources to care for individual plants, while considering funding and space limits. So, how can curators make the biggest impact towards conserving plant species? We present a promising method to quantitatively assess which plant species might be higher or lower conservation priority to an ex situ collection, using what we term ‘endangerment value’ – the value of collections for preventing plant extinction. We apply this method to four genera of high importance at The Morton Arboretum and showcase advantages of this approach as well as pitfalls. We found this method useful for priority setting, but note that the inclusion and exclusion of different data and how they are weighted impacts the ranking of priority species – an important lesson for any prioritisation method. We hope this method will inspire and help other botanic gardens to evaluate their current and future endangerment value and set priorities for maintaining and growing ex situ collections globally

Raising Rarity: creating meaningful and sustainable conservation outcomes through community-based outreach

A priority in plant conservation science is the identification of species at risk of extinction, allowing for conservation efforts to be focused on those that are most critically endangered to prevent their loss. A 2023 revision of threatened plants in Victoria found that 1,557 species remain under direct threat of extinction, despite conservation work being undertaken across the state to safeguard both individual species and plant communities. Although conservation efforts are fundamental to the protection of our flora, the persistently high number of threatened species illustrates a need to reimagine the way in which we approach conservation. Central to this is a need to engage more people across a broader cross-section of the community so that they can contribute to initiatives that effectively reduce the number of species at risk.Raising Rarity is a community-based outreach programme run by Royal Botanic Gardens Victoria (RBGV). It is designed to actively engage distinct sectors of the Victorian community in local plant conservation. The programme acknowledges that although the expertise provided by RBGV in areas that include conservation horticulture, seed ecology, population genetics, outreach and education is critical to plant conservation efforts, the engagement and involvement of the broader community is fundamental to creating sustainable plant conservation solutions. Raising Rarity achieves this by working with volunteers, school groups, regional botanic gardens, local councils and members of the nursery industry to grow and display rare and threatened Victorian plants in accessible horticultural settings. The initiative aims to increase public knowledge, awareness and hands-on involvement in plant conservation.There are four key components to the Raising Rarity programme: (1) school outreach; (2)local government outreach; (3) botanic gardens outreach in an initiative called Care for the Rare; and (4) commercialisation of an RBGV rare plant collection. This article provides an overview of each of these components and outlines future objectives for the Raising Rarity programme

Conservation Collections at the National Botanic Garden of Nepal – The Franklinia Taxus Project

Three species of Taxus occur in Nepal T. contorta, T. maireii and Taxus wallichiana,. All are under pressure from collection for medicinal use, habitat destruction and changing land use. In 2017 and 2018 fieldwork was carried out to collect seed, herbarium specimens, cuttings and information to improve protection of these species, funded by Fondation Franklinia. Collections were made for propagation, herbarium and molecular studies. Population level Information was also gathered to make national assessments for these species. This article traces the status of the living collections in the National Botanic Garden of Nepal (NBG) and the assessments made by the team comprising staffs of Department of Plant Resources (DPR) and Nepal Academy of Science and Technology (NAST) and Freelance botanist. Reference is made to work done prior to 2017 on the taxonomy and distribution of the species and which enabled efficient fieldwork thereafter. The establishment of a conservation collection at NBG provides a basis for research into yew species in Nepal and highlights the benefits of internationally collaborative projects to maintain conservation collections of threatened species in their country of origin

SHORT NOTE Air layering as a propagation method in glasshouse cultivation

The glasshouse renovation works being undertaken at the Royal Botanic Garden Edinburgh (RBGE) as part of the Edinburgh Biomes Project (2020–2027) pose a number of challenges to the horticulturists managing the plant collections. The grandeur of many of the larger specimens and the limit of available space are the most prominent of these. Air layering is a propagation method that until recently has not been used widely at RBGE. It has however proven to be a successful technique to maintain the genetic diversity of the collection while reducing both the need for space in propagation glasshouses and the level of aftercare required once propagation is complete. This Short Note explains the method used and highlights several successful propagations, illustrated with images, along with suggestions for implementing the method in the future

An investigation of large-leaved Gunnera L. (Gunneraceae) grown outside in Britain and Ireland

A molecular investigation of large-leaved Gunnera growing outside in Britain and Ireland was conducted. Two low-copy nuclear CYCLOIDEA-like genes (CYC-like 1 and CYC-like 2) and two chloroplast DNA regions (matK and psbD-trnT) were sequenced for 271 samples of Gunnera. While it was confirmed that genuine G. tinctoria is growing both in cultivation and in the wild, the results support recently published morphological and historical findings that the species G. manicata appears no longer to be present in Britain and Ireland. Instead, the plant under this name is G. × cryptica, a hybrid between G. manicata and G. tinctoria. The implication of this discovery for legislation on invasive non-native species where G. manicata and G. tinctoria are listed is explored

GUEST ESSAY Vive l\u27horticulture de conservation

Conservation horticulture is an emerging and increasingly important function for all botanic gardens, but it is an activity that can be difficult to explain and to promote. Part of that difficulty lies in its name, and a few alternatives are suggested in this Guest Essay – such as Care for the Rare, Raising Rarity, and Plant Rescue and Care Unit – all currently in use at Royal Botanic Gardens Victoria (RBGV) for more narrowly scoped but pioneering projects. In reimagining conservation horticulture at RBGV we want to draw on the public’s intrinsic interest in and affinity with plants, rather than taking a defensive stand against what is often called ‘plant blindness’. Raising Rarity 2.0 is likely to combine commercialisation of rare species, innovative blending of amenity and conservation horticulture, and even stronger partnerships with schools and local government. As I prepare to leave RBGV after 25 years in senior management of botanic gardens, I’m supporting a grassroots push from horticultural and research staff to add conservation horticulture (whatever we call it) to our already potent mix of nature, culture and science

Water sensitive design features: their function and effectiveness over ten years in a botanic garden

Water sensitive design (WSD) is a nature-based solution to urban stormwater problems which involves intercepting rainfall and stormwater from impervious surfaces using a range of devices. These devices rely on soils and plants to slow water flows, reduce water volumes and improve the quality of the water reaching our rivers, streams, lakes and oceans. Common devices used in Auckland, New Zealand are rain gardens and swales. Auckland Botanic Gardens (ABG) has applied a variety of these devices, often in ‘treatment trains’ and focusing on the use of native New Zealand plants, to solve an on-site environmental problem. ABG additionally supports research, advocates for the selection and effective maintenance of the native New Zealand plants, and educates the public about WSD. Recommendations for plant selection in Auckland for rain gardens and swales are made based on ten years of observations and trials at ABG

Parasitic plant cultivation: examples, lessons learned and future directions

Parasitic plants contain some of the most bizarre and fascinating organisms in the plant kingdom. Yet they are notable for their absence from botanic gardens’ plant collections and conservation strategies. Besides a handful of species, few are widespread in cultivation; indeed we estimate at least 76 per cent of species are entirely missing from collections today, and most of these have never been grown at all. Here, we place focus on the holoparasites, a group of plants long neglected due to their difficulty in cultivation. We review propagation breakthroughs in temperate and tropical botanic gardens to identify guiding principles for the cultivation of these neglected plants. We document the life cycle of a range of parasitic plants, and assess successful and failed attempts to propagate Rafflesia specifically, which has been the focus of decades of research. By uniting isolated case studies from around the world, we identify future directions for the cultivation and possible ex situ conservation of these botanical enigmas at a time when this is needed urgently. Finally, we recommend a dedicated global community of purpose as an intentional step forward: this could take the form of a Global Consortium for Conservation for parasitic plants, or a Parasitic Plant Specialist Group under the International Union for Conservation of Nature

Growing roses without chemicals: transitioning the collection at Auckland Botanic Gardens (New Zealand) 2000–2020

The Rose Garden at Auckland Botanic Gardens displays rose cultivars which perform well and remain healthy in Auckland, New Zealand, without pesticide applications. Miticides, insecticides and fungicides are not used. Suitable cultivars are chosen for public display to inspire gardeners and encourage visitors to make their own rose selections based on personal preferences from an array of proven performers. These are identified to the public as ‘Star Performers’. Here the process of trialling, identifying and displaying old shrub and modern rose cultivars that have achieved Star Performer status over the past 20 years is presented. This work demonstrates the role that botanic gardens can play in promoting sustainable horticultural practices

GUEST ESSAY A lesson for Botanic Gardens from the Covid-19 pandemic: reaching wider audiences through online activity

The power of botanic gardens to connect people to plants has traditionally stemmed from the physical interaction between visitors and living collections. However, the Covid-19 pandemic forced many botanic gardens to consider alternative, online programmes of engagement. Here I argue that this experience has been revelatory, showing us that digital approaches provide the power not only to reach a wider audience, but to connect more deeply with that audience if the content is carefully designed. The new opportunities provided for connecting people to plants will be an important part of botanic garden engagement programmes in the years ahead