Once referred to as “dry gardens (hortus siccus)” herbaria are centers of botanical discovery and research, and their collections are critical to our understanding of the world’s flora. People often collect leaves or flowers and keep them pressed between the pages of a book for sentimental or creative reasons. Herbarium specimens are made in largely the same way, though these pressed, dried plants are collected and preserved to study and document biodiversity. These specimens and the information they comprise are essential for research and education across many fields, including systematics and taxonomy, ecology, evolution, conservation biology, ethnobotany, paleobiology, and global change biology. Herbaria are libraries that store, organize, curate dried plant specimens to facilitate their access and study.

My father, an Asian botanist, travelled to herbaria in other continents to study specimens of Asian plants. I did not really think about the significance of this until I found myself working in the vicinity of some of the largest physical plant collections in the US. While I benefitted from having access to plants collected from every corner of the world just a short distance away, most do not. A disparity between where plants are collected and where they are preserved exists, and access to these resources are not equitable. The largest herbarium collections are situated in the global north, mostly in Europe and North America. Though many cultures have collected and preserved plants in various ways, herbaria as we know them today are largely a European creation, and like other natural history collections, many have grown with the colonial expansion of imperial powers. Fueled in part by the desire to exploit the biological resources of colonies abroad, large amounts of living and preserved plant specimens were moved to institutions in colonizing nations. Botany was the science par excellence of colonial empires. Though many natural history museums and other cultural institutions are increasingly engaged in efforts to address their colonial legacy, such efforts have largely been focused on publicly exhibited human- and animal-related collections. Botanical collections have received less attention, perhaps because few herbaria offer public displays and interest in plant specimens is comparatively lacking among the populace. 

The first step towards addressing the appropriation of plant diversity and to open a dialogue to help move us towards a more inclusive future is understanding the extent of disparity in herbarium collections across the globe. To this end, our international team of scientists and curators from herbaria on every continent analyzed over 85 million plant specimen records from the Global Biodiversity Information Facility (GBIF), the largest repository of biodiversity data, and also surveyed physical herbarium collections across the world. Recognizing the sovereignty of a nation’s biological resources and that biodiversity can be best studied where it occurs, we aimed to quantify the proportion of specimens that do not reside in their country of collection and are housed in (formerly) colonizing countries.

Our results suggest that botanical collection trends across the last four centuries strongly bear the imprint of colonialism, both in the plant specimen records hosted online and the physical collections we examined. Despite the era of overt colonialism drawing to an end after the Second World War, the historical trend of specimen movement from Africa, Asia, and South America to Europe and North America has largely remained constant. In nature, biological diversity generally increases as we move from polar to equatorial regions of the globe – the movement of plant specimens thus runs counter to the latitudinal gradient of biodiversity. Our data suggest that centuries of colonialism have contributed to a reverse latitudinal gradient of preserved plant diversity in the form of herbarium collections. The increasing availability of digital images and metadata of herbarium specimens have made it easier to access and utilize these specimens from afar. However, our survey of physical herbarium collections indicates that only a small portion of specimen data have been digitized and shared online to date. Along these lines, digitization requires significant investments in infrastructure and personnel and adequate funding is often lacking, even for institutions in developed countries. Indeed, several of our collaborators and authors – some of whom work at comparatively large and well-funded herbaria – note that even estimating the size of their collections is difficult as only a portion of specimens have been databased, and formal inventories seldom exist. Given that our results are based on a comparatively well-curated subset of herbarium collections and their digital derivatives, it is highly likely that the disparities in both physical and digital collections among previously colonized countries and their colonizers are much larger than our assessment suggests. This disparity not only impacts the capacity for basic research, but public and commercial endeavors that seek to utilize biological resources and their derivatives as well.

As with the herbarium collections we examined, our study is not free from the biases of the Western scientific system that we rely upon to understand and interpret the natural world. There were many thoughtful dialogues among members of our team and peer-reviewers regarding the interpretation of our data, how to define and describe colonial activities and their relation to botanical collections, and how our own thoughts and conclusions may have been shaped by imperialist thinking and colonial endeavors. These discourses highlight the complexity of the issues we address – our study is only the first step towards understanding how colonial activities have shaped plant collections and discussing how we may move towards a more inclusive global herbarium. Though there have been efforts to acknowledge and remedy the disparity between where plant biodiversity naturally exists and where it is artificially housed and studied, they are few and far between and a profound set of challenges still lie ahead. Herbarium collections are not free from the sociopolitical realities that belie their formation, and we should not avert our gaze from the inconvenient origins of these otherwise valuable resources.