pollen

Latin pollen (genitive pollinis) meant 'fine flour,' 'fine dust,' or 'powder.' The Romans used the word for any finely ground powder, including wheat flour and cosmetic powders. The botanical application — the powder produced by the anthers of flowers — was first recorded in English in the 1760s, when Linnaeus and his contemporaries were working out the sexual reproduction of plants. Before that, nobody knew what pollen was for. The dust existed. Its function was invisible.

Nehemiah Grew, an English botanist, proposed in 1682 that pollen was the male element in plant reproduction — a radical claim at the time. Rudolf Jakob Camerarius confirmed it experimentally in 1694, demonstrating that plants deprived of pollen could not produce seeds. The discovery that flowers have sex was controversial. Linnaeus built his entire classification system on it, grouping plants by the number and arrangement of their stamens (male parts) and pistils (female parts). His system was criticized as obscene. The Encyclopédie noted that Linnaeus had turned botany into something best not discussed in polite company.

Allergic rhinitis — hay fever — is caused by pollen from wind-pollinated plants, particularly grasses, ragweed, and trees. Approximately 30 percent of adults and 40 percent of children worldwide suffer from pollen allergies. The condition was first described by John Bostock in 1819, who initially believed it was caused by hay. The real culprit was identified as pollen in the 1870s by Charles Blackley, who collected pollen samples using kite-borne sticky slides. The dust the Romans named is the allergen the modern world dreads each spring.

Palynology — the study of pollen and spores — is used in forensic science, archaeology, and climate research. Pollen grains are nearly indestructible, surviving in sediment for millions of years. Each species produces pollen with a distinctive shape, identifiable under a microscope. A pollen profile from lake sediment can reconstruct the vegetation of a region across millennia. Forensic palynologists have used pollen traces on clothing and vehicles to link suspects to crime scenes. The fine flour that the Romans named is now evidence.