BAUHINIA – Zeitschrift der Basler Botanischen Gesellschaft

A second Renaissance of herbarium-based research, almost five centuries after their invention

Jurriaan M. de Vos, Jürg Stöcklin — Sun, 31 Dec 2023 00:00:00 +0000

The present issue of Bauhinia presents the Proceedings of the Bauhin2022 conference, that the authors organized at the University of Basel, Switzerland, from 15-16 September 2022 in honor of Caspar Bauhin (1560–1624), celebrating his pioneering Flora of Basel 400 years after its publication (Bauhin 1622). This meeting, with ca. 100 participants from 14 countries, with 25 invited and contributed talks, 31 posters, and a discussion workshop fueled our thinking on the increasingly pivotal role of herbaria in current day research.

A 150-year-old herbarium exemplifies change of a regional flora

Michèle Büttner, Urs Weibel, Michael Jutzi, Ariel Bergamini, Rolf Holderegger — Sun, 31 Dec 2023 00:00:00 +0000

The loss of biodiversity in terms of plant species in a certain region can be shown by a comparison of historical herbarium records with the present-day occurrence of species. This holds especially true for time periods before 1900, when only few floristic data are otherwise available. Such a comparison can also show whether the distribution area or the abundance of plant species have changed, which habitat types were especially affected by extinction or whether species with specific environmental requirements showed higher extinction rates than ubiquists. Corresponding results can guide conservation authorities in defining appropriate management actions.

The genomic uses of a 200 year-old herbarium – Pitfalls and potentials

Sun, 31 Dec 2023 00:00:00 +0000

Major herbaria, such as the one hosted by the botanical garden of Geneva (G) have played a central role in the development of plant systematics over the last 200 years. Today, advances in high throughput sequencing technologies (HTS) together with the development of targeted capture, where DNA extracts are enriched for preselected loci using hybridization probes prior to sequencing, have considerably improved the use of herbaria as a source of genetic data, opening new avenues in the study of plant biodiversity.

Bridging herbaria cultural heritage and digital art – Immaterial herbaria

Sun, 31 Dec 2023 00:00:00 +0000

Migratory movement changes the way in which people perceive and feel their nations. Art allows us to enquire about the way members of diasporas are stimulated and confronted with a plethora of feelings as loss and grief, empathy, hope and joy when they see familiar plants collected from their countries of origin among herbarium samples. In the case of the Venezuelan diaspora, nostalgia for a recent past and memories of the homeland configure the imagined Venezuelan nation now that people living abroad („diasporic subjects” in the sense of Martinez Parra 2020). Some Venezuelans take plants from their gardens with them when they leave their country. Many of these people take orchids with them, that remind them of their origin and which they nurture in their new countries.

Towards digitizing the botanical legacy of Fritz and Paul Sarasin in Basel and Zurich

Aurélie Grall, Alessia Guggisberg, Reto Nyffeler, Jurriaan M. de Vos — Sun, 31 Dec 2023 00:00:00 +0000

The botanical heritage of multitalented naturalists Paul Benedict (1856–1929) and Karl Friedrich (Fritz) (1859–1942) Sarasin of Basel is poorly known. The second-degree cousins from Basel inherited great wealth, which funded their expeditions to the tropics in India, Sri Lanka, Sulawesi, and New Caledonia. Both were doctors in zoology with interdisciplinary interests from geography and anthropology to botany. They mixed race theories with traditional descriptions of biodiversity, blurring boundaries between anthropology and natural sciences. With the help of the local colonial governments where they travelled, they avidly collected many thousands of natural history objects and human artefacts, now kept in institutions across Europe.

Stable isotopes from herbarium specimens reveal physiological responses of plants to global change

Ansgar Kahmen, Daniel B. Nelson, Jurriaan M. de Vos, David Basler — Sun, 31 Dec 2023 00:00:00 +0000

Investigating the impacts of global environmental change on plants remains a challenge. Experiments that scale from leaf to ecosystem have provided important insights into the ways plants and ecosystems respond to changing environmental drivers. Yet, experiments are often short-lived and can not realistically simulate long-term environmental changes. Monitoring programs and historical observations are thus valuable alternatives for studying the impact of environmental change on plants. These are, however, unfortunately rare and often poorly suited to identify the mechanistic and physiological basis by which changes in the environment impact plant life. Analyses of biological collections and in particular herbarium materials could be a valuable complementary approach that allows assessing functional responses of plants to global environmental change.

Using herbarium specimens to test for effects of climate change on the time of flowering

Thea Kull, Kätlin Langerpaur, Tiiu Kull — Sun, 31 Dec 2023 00:00:00 +0000

Temperature change in different seasons has various impacts on phenological events. In recent times herbarium material has become more relevant in studying ecological consequences of climate change. Digitalized historical herbarium provides useful material in addition to observational data. This study is the first to use Estonian herbarium material to test the usefulness of herbarium material for studying phenological changes due to climate change.

Finding biotic anomalies described in specimen label text is a challenge that artificial intelligence can address

Sun, 31 Dec 2023 00:00:00 +0000

Biodiversity specimen collectors are on the front lines of observing biotic anomalies, some of which herald early stages of significant changes (e.g., the arrival of a new disease; Pearson and Mast 2019). Online data sharing has opened new possibilities for the discovery of anomaly descriptions on collectors’ labels, but it remains a challenge to find these needles in the haystack of many millions of specimen records available at aggregators like iDigBio and Global Biodiversity Information Facility. In a recent community survey, over 200 collectors identified 170 unique words and phrases (e.g., atypical) that they would use to describe six types of anomaly (Pearson and Mast 2019). Left unanswered was the relative efficiency with which anomaly descriptions can be found using the simple presence of these words. Here, we address that question with a focus on one type of anomaly (phenological; related to the timing of life history
events) and ask a second question: can we further improve the efficiency of anomaly description discovery by engaging artificial intelligence (AI)?

SNP genotyping and environmental niche modelling using herbarium specimens of the northern dragonhead, Dracocephalum ruyschiana (Lamiaceae)

Sun, 31 Dec 2023 00:00:00 +0000

Maintenance of genetic diversity is a central aim of species conservation, given its positive effect on species survival and adaptation in a changing environment. Data from different time points is key for understanding how populations behave under various conditions. In this regard, herbarium specimens are an invaluable source of information from the past. Still, utilizing archived biological material for studying trends of genetic diversity offers challenges such as DNA degradation and the lack of standardized, cost- and time efficient methods.

What does the „true” Boerhaave herbarium tell us about the practice of collecting plant specimens in the botanical garden Leiden?

Aleida Offerhaus, Tinde van Andel, Anastasia Stefanaki — Sun, 31 Dec 2023 00:00:00 +0000

The Dutch physician Herman Boerhaave (1668–1738) was famous for his clinical teaching, but his botanical research was also renowned. Boerhaave (Fig.1) inspired his pupils to set up botanical gardens and devise their own classification systems. His research resulted in the publication of two editions of the garden catalogue of the Leiden Hortus Botanicus, of which the latter (Boerhaave 1720), was deemed important enough to be used extensively as reference by Linnaeus (Linnaeus 1737). Devising a classification system was a major enterprise and must have required a substantial herbarium. Two herbaria were attributed to Boerhaave, but it appears unlikely – even though they have not yet been researched – that they were actually composed by him. From the collection of Naturalis Biodiversity Center, Leiden, we selected 100 specimens that were listed as collected by Boerhaave and verified 88 specimens as having been collected by Boerhaave. However, this small number raises the following questions: What happened to the rest of the herbarium that Boerhaave created? And how can we recognise a Boerhaave specimen?

Looking back to move forward – Impact of historical moss specimens on modern systematics

Michelle J. Price — Sun, 31 Dec 2023 00:00:00 +0000

Natural history collections reflect our desire to understand the living world. Each collection is unique based on how it was composed, who composed it, where the specimens originated from, and how it has been enriched. Natural history institutions preserve, curate and enhance their collections on an ongoing basis and they serve as a powerful scientific resource. Collections provide a window into past, present and future biodiversity via the information contained on and in specimens. They play a crucial role in the documentation,
description and understanding of species themselves, with the specimens held in global collections forming the foundation for all taxonomic endeavours.

Using herbarium specimens, botanical gardens, historical data, and citizen science to study climate change

Sun, 31 Dec 2023 00:00:00 +0000

Over the past two decades, researchers and others involved in plant science have developed innovative and powerful methods to investigate the effects of climate change on plants.

Ampelographic (grapevine) collection in 230-year-old Herbarium Wolnyanum (Sremski Karlovci, Serbia)

Milica Rat — Sun, 31 Dec 2023 00:00:00 +0000

The herbarium collections in Southeast Europe were mostly founded in the 19th century or later. However, the oldest collection in Serbia dates back to the 18th century. It was founded in the Habsburg Monarchy as a school herbarium in the first Serbian gymnasium in Sremski Karlovci, where it is still kept today. The founder was Andreas Wolny (1759–1827), first professor of geology, mineralogy, botany and zoology (and various other subjects), and soon after professor and director of the gymnasium. He worked and lived in Sremski Karlovci in the period from 1793 to 1816.

Looking into 16th-century botanical history to understand the complex taxonomy of Tulipa sylvestris in Europe

Aastasia Stefanaki, Tilmann Walter, Tinde van Andel — Sun, 31 Dec 2023 00:00:00 +0000

Tulipa sylvestris is a small yellow tulip that was introduced to northern Europe in the 16th century. Unlike the tulips that came from the Ottoman empire and gave birth to modern cultivars, T. sylvestris came from the Mediterranean and became a garden escapee that successfully naturalized across Europe. Its taxonomy is complex due to morphological diversity, polyploidy and naturalization of cultivated plants. Two subspecies are provisionally accepted in Europe: subsp. australis, a diploid native in the Mediterranean (up to Central Asia) that grows on mountainous rocky grasslands, on poor soils; and subsp. sylvestris a tetraploid that is naturalized across Europe and grows in rich soils at low altitudes, mainly at field margins, vineyards and gardens. Sometimes these two subspecies are regarded as distinct species, but their taxonomic delimitation is unclear.

What did 16th-century tomatoes look like?

Tinde van Andel, Anastasia Stefanaki — Sun, 31 Dec 2023 00:00:00 +0000

Soon after the Spanish conquest of the Americas, the first tomatoes were presented as curiosities to the European elite and drew the attention of 16th-century Italian naturalists. Despite their scientific interest in this New World crop, most Renaissance botanists did not specify where these „golden apples” or „pomi d’oro” came from. It is likely that tomatoes were brought to Europe after the Spanish sieged the Aztec city of Tenochtitlan (now Mexico City) in 1521 and after they conquered the Peruvian Inca emperors in 1531. Tomatoes and other New World domesticates must have been brought to the Spanish court, and were probably planted in the royal gardens
in Madrid, after which they were likely shipped from Sevilla to Italy, but no written evidence have been found so far for these events. The debate on the first European tomatoes and their origin is often hindered by erroneous dating, botanical misidentifications and inaccessible historical sources. So, who saw the first 16th-century tomatoes that entered Europe? What did they look like? Who made the first botanical description, collection and/or illustration? And where did these tomatoes come from?

Network analysis of the herbarium collection of the Moravian Church from the 18th century

Sun, 31 Dec 2023 00:00:00 +0000

The Herbarium Dresdense (DR), Germany, houses about 500 000 specimens of worldwide origin. One of the oldest collections is the Herbarium Barbiense of the Moravian Church from the mid to the late 18th century. On their mission to spread Christianity, the Moravians settled on many continents and took the advantage of exploring culture and nature of their new home countries. Being excellent observers and documentarists, they left a barely explored corpus of objects and texts of tremendous importance for natural sciences and humanities. Since 1754 the educational centre of the community was located in Barby, Saxony-Anhalt, Germany. To support the scientific training and to gather objects send home by the missionaries, a cabinet of natural curiosities was established in 1756. The collections of minerals, fossils, conchylia and plants were unique and soon attracted other European academics.

Flora of the Canary Islands – revised checklist to a classic arena of botany

Anna Walentowitz, Walter Welss, Carl Beierkuhnlein — Sun, 31 Dec 2023 00:00:00 +0000

The Canary Islands are a popular location for botanical collections that resulted in a series of seminal works, including the description and documentation of many endemic plant species (Fig. 1, 2, 3) in herbaria. Viera y Clavijo, Christ, Webb, Berthelot, Sventenius, Pitard, Kunkel, or Bramwell, to name but a few, majorly contributed to the knowledge about the flora of the Canary Islands. Alexander von Humboldt’s botanical description of Tenerife during his stay in 1799 also motivated Charles Darwin to explore the island. Unfortunately, Darwin was not allowed to set foot on land during his voyage with the Beagle due to quarantine restrictions. In recent years, a number of data bases containing detailed information about the plants of the Canary Islands emerged. This botanical legacy evokes the expectation that detailed information about the flora of the archipelago is available, with high agreement about taxa and status between different sources. To test this expectation, we elaborated an extensive floral checklist for the Canary Islands, documented which taxa are accepted in global taxonomic reference systems, and additionally checked their coverage in databases that are a common sources in biogeographical and ecological research.

A plant’s path to publication – Caspar Bauhin (1560–1624) and Johann Theodor de Bry (1561–1623)

Karen Reeds, Davina Benkert — Sun, 31 Dec 2023 00:00:00 +0000

The Basel botanist Caspar Bauhin is justly famed for bringing order to late Renaissance botany. Through his Phytopinax (Basel, 1596), Prodromos Theatri Botanici (Frankfurt, 1620), and, above all, Pinax Theatri Botanici (Basel, 1623), Bauhin prepared the way for his Theatrum Botanicum. He envisioned this as a comprehensive, systematic, illustrated account of all six thousandplus plants known to him. His contemporaries had high regard for these works; a century later, Linnaeus found them indispensable. Today, they remain our key to pre-Linnaean botanical literature.

Caspar Bauhin’s life (1560–1624) – Academic career, achievements as a botanist and his herbarium

Jürg Stöcklin, Jurriaan M. de Vos — Sun, 31 Dec 2023 00:00:00 +0000

Caspar Bauhin was born 1560 in Basel as a refugee child from a distinguished Protestant family which escaped persecution of the Huguenots in France. He studied medicine and botany at the University in Basel, in Italy and France and became the first professor for medical Anatomy and Botany in Basel. He is the founder of one of the first Botanical Gardens north of the Alps, and the first to offer regularly botanical excursions and courses in systematics and taxonomy for medical students. In his many publications, C. Bauhin aimed to give a systematic overview of all c. 5600 plant species known at the time, based on meticulous comparison and descriptions by himself, renaming them by distinguishing clearly between genus and species and by adding the synonyms of other authors. Thereby Caspar Bauhin was paving the way for botany as an independent scientific discipline and for Linnaeus, who heavily relied on him for the further development of botanical systematics and nomenclature more than a century later. His herbarium, which today is kept at the University of Basel, served him as working tool and included more than 4000 species, which he collected himself or through exchange with a wide net of correspondents. Not the least of Bauhin’s achievements is the publication in 1622 of one of the first comprehensive local floras, which until today is used as a reference for floristic changes in the surroundings of Basel.

From Brunfels to Bauhin – The first 100 years of „botany” in the German-speaking area

Tilmann Walter — Sun, 31 Dec 2023 00:00:00 +0000

This article examines how Caspar Bauhin (1560–1624) became famous as a scientific author and University teacher in Basel focusing on the evolution of scientific practices such as botanizing and herbarizing in the German-speaking world. In the early 16th century German-speaking publishers were the first to sell well-illustrated books that would be of great help to readers in identifying plants. After 1550, Swiss and German physicians such as Felix Platter, Leonhard Rauwolf, Kaspar Ratzenberger and Johann and his brother Caspar Bauhin began collecting plants for their herbaria, some of which are among the oldest still preserved today. The Rauwolf herbarium, with its most „scientific” design, shows how plant identification was done in practice. Rauwolf also was the first to leave behind a comprehensive report of his fieldwork in Syria, Lebanon and Iraq, written in German. In Basel, Caspar Bauhin was to become a particularly influential academic teacher in the German-speaking world and beyond when he took over the newly established chair for Botany and Anatomy in 1589. He trained a total of nearly 800 students during his University career. Moreover, Bauhin’s extensive correspondence comprises over 2500 letters and provides insights into the lively discussions among the fellow botanists with whom Bauhin corresponded.

Impossible to press? – Succulents in Renaissance herbaria

Urs Eggli, Reto Nyffeler, Felix Merklinger — Sun, 31 Dec 2023 00:00:00 +0000

Several Renaissance herbaria, including the herbarium by Caspar Bauhin, contain preserved specimens of different succulent plants, such as cacti, stonecrops, palm lilies or aloes. In view of the difficulties experienced even today when preparing succulents for the herbarium, the efforts of the Renaissance botanists to meet this challenge is remarkable. The view that succulents by definition are unsuitable for pressing for the herbarium, as for instance expressed by Richard Bradley in his 1716 book, prevails to these days. We first provide a condensed overview of standard preparation techniques for succulents advocated in the literature of the past forty years. Then, a selection of specimens of succulents in early herbaria, from several plant families, is discussed and the preparation methods used at that time, and possible solutions of the difficulties involved, are outlined.

Plant exchange networks in the 19th century – 200 years of citizen science

Christof Nikolaus Schröder — Sun, 31 Dec 2023 00:00:00 +0000

Plant exchange networks in the 19th century have been investigated in a largescale study, firstly by identifying as many plant exchange organizations (PEOs) as possible and secondly by searching for exchange partners in a 19th century private herbarium from Southwest Germany, and by analysing exchange activities related to the rare central European endemic Saxifraga rosacea subsp. sponhemica (C.C.Gmel) D.A.Webb. In this paper a first overview on selected results is given: 101 PEOs – founded from 1819 to 1947 – with a total of 3000 to 5000 members have been found; they distributed 15 to 20 million specimens; 111 collectors have been identified in the exemplary private herbarium, from which specimens have been found in 27 herbaria; S. rosacea subsp. sponhemica has been collected by 242 individuals, 233 exchange partners received duplicates distributed by 12 PEOs.

The collection of letters addressed to D.F.L. von Schlechtendal in the University herbarium in Halle (Saale), Germany (HAL)

Natalia Tkach, Martin Röser — Sun, 31 Dec 2023 00:00:00 +0000

D.F.L. von Schlechtendal (1794–1866) was one of the most important botanists of the 19th century. From 1833 to 1866 he was professor of botany at the University Halle-Wittenberg, where his collection of some 70 000 plant specimens is kept. Schlechtendal described more than 1600 new taxa, including 78 genera, mostly from the New World. Schlechtendal’s dense network of scientific contacts is documented by his correspondence, comprising some 5600 letters he received from about 500 persons, including many famous contemporary botanists, natural scientists, travelers and plant collectors. The letters mostly refer to publications and scientific questions concerning the journals ,Linnaea’ and ,Botanische Zeitung’ edited by Schlechtendal. In particular, the letters of scientists dealing with African, Central and South American, and Australian plants are an important source of taxonomic information. The letters are mostly written in the old German Kurrent script, the ink is fading and the paper is disintegrating. We therefore have started to transliterate all letters (54 % completed), index and digitize them and make them available online. Here we explain their importance, highlighting letters dealing with the plants from Humboldt’s and Bonpland’s travels and from the correspondence with R.A. Philippi
(Chile, 1808–1904) and H. Christ (Switzerland, 1833–1933).

Herbarium DNA degradation – Falling to pieces non-randomly

Freek T. Bakker, Lia Hemerik — Sun, 31 Dec 2023 00:00:00 +0000

Post-mortem damage in herbarium DNA, mostly from 18th and 19th century collections, and with specimens usually heat-treated for conservation, consists mainly of genome fragmentation (single- and double-stranded breaks) rather than miscoding lesions. With typical herbarium DNA fragment sizes encountered (20–200 6 https://www.jstor.org/stable/1220096 bp) this easily leads to insert sizes in library construction being smaller than Illumina read lengths applied (i.e. 100–250 bp). Using a previously-published series of 56 genome-skimmed herbarium DNA extracts representing 10 angiosperm families, overlapping read pairs were found to occur in roughly 80 % of all read pairs obtained. After merging such overlapping pairs, the resulting fragments and their length-distributions are considered to reflect actual DNA fragmentation. Similar to occurrence in ancient DNA, we found over-representation of purines at fragment-ends in herbarium material. Distributions of fragment lengths fit gamma rather than exponential distributions, without apparent correlation with specimen age. The observed gamma distributions would indicate higher-order degradation kinetics, implying multiple processes acting during degradation. Possibly, the genome skimming data used here, in which repetitive sequences or compartments are over-represented, has biased genomic fragment-length distributions and half-lives as compared to the non-repetitive fraction of plant genomes, but no data was available to test this hypothesis. Overall, our results imply that we cannot confirm whether a plant archival DNA half-live exists and what its rate would be.

Improving procedures for obtaining Sanger sequences from old herbarium specimens

Mika Bendiksby, Lisbeth Thorbek, Charlotte Bjorå, Rune Halvorsen — Sun, 31 Dec 2023 00:00:00 +0000

Because DNA degrades over time, extracting DNA of sufficient quality for sequencing is presumed to be more difficult from older than younger herbarium specimens. Although massive parallel sequencing techniques have clear advantages when it comes to sequencing ancient DNA, Sanger sequencing is still in frequent use, prompting us to test and improve its application on herbarium specimens. During molecular phylogenetic investigations of the subfamily Lamioideae (Lamiaceae) and subgroups, we extracted DNA from 651 herbarium specimens collected between 1826 and 2006 using regular mini-prep methods. The aim was to obtain DNA of sufficient quality for Sanger sequencing of various plastid and nuclear genetic markers. Here, we report successful Sanger sequencing of the commonly used plastid marker, rps16, as a conservative measure of DNA quality, and logistic regression to investigate the relationship between age of the material and DNA quality. Our result indicates that the upper age limit for obtaining DNA suitable for Sanger,sequencing from herbarium specimens using regular mini-prep DNA extraction methods has not been reached. After simple modifications to the regular DNA miniprep and PCR procedures, at least one genetic marker was successfully sequenced for about 90 % of the specimens tested, the oldest being 168 years old. Jointly, despite the technique’s drawbacks, these results demonstrate a high success rate of Sanger sequencing of herbarium specimens.

An integrated approach to studying tropical plant diversity – Taxonomic monographs, herbarium specimens and the sweet potato

Pablo Muñoz-Rodríguez, John R.I. Wood, Robert W. Scotland — Sun, 31 Dec 2023 00:00:00 +0000

Recent decades have witnessed a massive increase in data accumulation, but our knowledge of the world’s biodiversity is still fragmentary: data accumulation has not been matched by a parallel taxonomic effort, and many groups of organisms have never been comprehensively studied. In the current context of climate change and biodiversity loss, we need to accelerate taxonomy and species discovery. This, however, requires a good taxonomic and phylogenetic framework, which is lacking for most groups of tropical plants. This contribution discusses the role of botanical monographs in accelerating taxonomy. We argue that the increasingly easier access to data in the world’s herbaria and the availability of DNA sequence data place botanists in an unparalleled position to produce taxonomic monographs, the forefront of taxonomic research. We illustrate the discussion with the results of a monographic study of the genus Ipomoea (Convolvulaceae). We integrated herbarium-based morphological studies with techniques of phylogenetic and genomic analysis of thousands of specimens to develop more robust species delimitation hypotheses and a comprehensive phylogenetic framework. Monographs such as ours have implications for other disciplines beyond taxonomy. We specifically show how it enabled important discoveries related to the origin of sweet potato, a worldwide staple crop.

A large phylo-floristic study on the present and future assembly of the Wisconsin flora – An area unique in North America

Kenneth M. Cameron — Sun, 31 Dec 2023 00:00:00 +0000

With 1.4 million specimens the Wisconsin State Herbarium (WIS) is one of the largest in the Americas and Wisconsin offers botanists a unique opportunity to study species representing a confluence of global biomes. The state harbors >2640 species of vascular plants which have been sequenced for the two-gene plant DNA barcode to reconstruct a community phylogeny. At the same time >300’000 georeferenced specimens were used with bioclimatic and soil data to produce species distribution models for the flora, then subsequently aggregated to determine current and future patterns of species richness and phylogenetic diversity. Among the many surprising results uncovered are predictions that whereas species richness will increase as c. 850 taxa move into the state, c. 242 species will become extirpated by 2070. These most vulnerable species will not be affected at random. Furthermore, models suggest that Wisconsin’s projected climate will be unsuitable for most species to be able to retain their present distributions; only 65 % will be able to retain more than half of their current distributions. However, the state’s well known unglaciated Driftless Area may be able to serve as an Anthropocene refugium better than anywhere else in the region and should be targeted for increased land conservation.

The impact of climate change on plant distribution and niche dynamics over the past 250 years in Switzerland

Jessica Wang, Markus Fischer, Stefan Eggenberg, Katja Rembold — Sun, 31 Dec 2023 00:00:00 +0000

Herbarium specimens provide an irreplaceable source of historical plant distribution data, enabling analysis of changes in plant distribution spanning centuries. Most studies on plant distribution shifts focus on recent decades and rare species, especially along elevational gradients. We examined about 2000 historical herbarium specimens from the Botanical Garden of the University of Bern, representing 30 plant species from five Swiss lowland habitats (six species per habitat) dating back to 1768 and covering all Swiss cantons. All historical data were transcribed, georeferenced and then combined with current data resulting in about 170 000 plant records over 250 years. Combined with climatic data from the same period, we found that all habitats increased their potential distribution area with a significant gain in the semi-arid grasslands (+8.15 %, p-value = 0.031). On species level, 75 % of the selected species expanded their distribution, while 25 % of the species retracted. Despite these shifts, 90–99.6 % niche stability was observed between historical and current climatic niches across all species. Shifts in co-occurring species were specific to the species, not to the habitat. The consistent overlap in historical and current climatic niches suggest that distribution expansion is due to the growth of areas with suitable climates, pointing to climate change as a driving factor for plant distribution changes over the past 250 years.