State of the World's Plants and Fungi is an international report series produced by the Royal Botanic Gardens, Kew, which since 2016 has brought together the latest knowledge on the world's plants and fungi.
The report is based on peer-reviewed research published in a special issue of the journals New Phytologist and Plants, People, Planet, and includes contributions from researchers and institutions from around the world.
This year's report explores, among other topics, how digitisation and new analytical methods are creating new opportunities for research based on natural history collections and their associated data.
Historic plant collections are playing an increasingly important role in research. This is one of the findings of the latest State of the World's Plants and Fungi report from the Royal Botanic Gardens, Kew, which brings together the latest international knowledge on the world's plants and fungi.
Several researchers from the Natural History Museum Denmark contributed to the report, including through research on new ways of using historic plant collections to understand environmental change over time.
– The world's herbaria contain around 400 million plant specimens collected over the past 500 years. These collections represent an enormous but long underutilised source of new knowledge about biodiversity and climate change. Digitisation and new analytical methods now make it possible to use that knowledge on a much larger scale than before, says Natasha de Vere, Professor and Curator of Botany at Natural History Museum Denmark.
One of the studies featured in the report demonstrates how reflectance spectroscopy – the measurement of how light is reflected from plant specimens – can be used to extract new information from historic herbarium specimens. The method makes it possible to derive information about plant traits and function directly from dried plant specimens, some of which are more than 100 years old.
– Traditionally, herbarium specimens have primarily been used for species identification and for documenting plant distributions. With this new analytical method, we can now also gain new insights into plant structure, chemistry and function directly from dried plant specimens. This means that historic collections can now be used to answer research questions that could not have been imagined when the plants were originally collected, explains Natalie Iwanycki Ahlstrand, Assistant Professor and Curator at Natural History Museum Denmark.
The report also shows how digitised herbarium collections can be used to investigate how plant flowering changes in response to climate change.
The analyses are based in part on information about when and where plants were collected, as recorded on herbarium specimens.
– Every herbarium specimen tells us where and when a plant was collected. When we combine millions of these observations across collections and countries, we can begin to see patterns that would otherwise remain invisible. This gives us a unique opportunity to investigate how plant life cycles are changing in response to climate change,” explains Natalie Iwanycki Ahlstrand.
Researchers from the Natural History Museum Denmark contributed to analyses of millions of digitised plant specimens from collections around the world. The results show that, globally, flowering times have shifted by an average of 2.5 days per decade over the past century. At the same time, the analyses show that the length of flowering seasons is changing in many parts of the world, although the trend does not follow the same pattern everywhere.
For researchers to make use of the millions of digitised plant records that are now available online, it is essential that information on species, localities and collections can be compared across institutions and countries.
One of the museum’s contributions to the report has therefore been the development of methods for standardising and linking digital plant data from different collections. This work has, among other things, been used to update and quality-assure the digital flora of Greenland (Kalaallit Nunaat) and make it easier to use in biodiversity and climate change research.
– Natural history collections contain enormous amounts of knowledge, but their full potential can only be realised when data from many different collections can be used together. By harmonising the information, we can gain a much more accurate picture of biodiversity and how it changes across both time and place,” says Brandon Samuel Whitley, PhD Research Fellow and Research Assistent at Natural History Museum Denmark and lead author of the study.
Overall, the report demonstrates the growing importance of historic plant collections as a foundation for research into both biodiversity and climate change.
The report brings together contributions from researchers and institutions from around the world, including several researchers from Natural History Museum Denmark.
New Analytical Methods for Historic Plant Collections – Development of new methods that make it possible to extract information about plant traits and development directly from historic herbarium specimens.
Plants and Climate Change – Research into how digitised herbarium collections can be used to investigate plant growth, flowering, and responses to climate change, including in the Arctic.
Plant Flowering in a Changing Climate – Research into how millions of digitised plant specimens from herbarium collections can be used to map changes in flowering times and plant life cycles in response to climate change.
Digitisation of Biodiversity Data – Research into the use of digitised herbarium collections to strengthen knowledge of biodiversity, including efforts to update the checklist of Greenland’s plant species.
New Fungal Species – Research on newly discovered fungal species, including the description of Purpureocillium atlanticum – a fungus found in Brazil’s Atlantic rainforest, where it grows from a trapdoor spider that it has infected and consumed. The discovery was ranked number one on Kew’s list of the Top 10 New Species of 2025.
