Digitizing collections to unlock the full potential of palynology: a case study with the Smithsonian palynology collection

Abstract

Large palynological collections have been built over decades and contain vital information. However, they are often difficult to access and use effectively. What is the point of having such collections if they are not fully utilizable? To solve this problem,we digitized the Smithsonian palynological collection using both light and confocal microscopy. We digitized the pollen of 12,000 species and took 40 million photos. Our image library will support a wide array of applications, including environmental monitoring, public health, biodiversity studies, paleoclimate, and the analysis of land-scape changes across spatial and temporal scales. It will also aid in geological correlations used in water exploration and in hydrocarbon storage/production.Summary: Palynology is a century-old practice, contributing data to various fields, from geology to medicine and forensics. Palynological analyses are highly time-consuming and involve visually finding, identifying, and counting thousands of palynomorph grains on microscope slides. These analyses are especially challenging in high-diversity tropical settings. Fortunately, the development of deep learning and the capability to digitize entire microscope slides are allowing palynology to enter a new era. Foundational to this transformation is building solid digital collections that can be achieved by digitizing botanical collections. We are digitizing the Smithsonian palynological collections, which contain 18,000 species, most of which are Neotropical taxa in the Graham Pollen Collection. This digital product consists of high-resolution images of different types transmitted light, differential interference contrast, and optical superresolution (Airyscan) which will be freely available and lay the groundwork for training deep-learning models and applying novel image analysis to palynomorph morphology. Image quality matters, so we outline the best practices we have developed throughout the years of imaging and experimentation. High-resolution imaging of palynological collections holds the key to unraveling the full potential that the study of pollen and spores can offer.