Common Pimpernel

<em>Lysimachia arvensis</em>, the common pimpernel or scarlet pimpernel, is a low-growing annual flowering plant in the family Primulaceae, formerly classified in the genus Anagallis. It is characterised by small, typically brick-red to salmon-orange flowers that close in overcast conditions or during the afternoon, earning it the folk name "poor man's weather-glass." The species typically inhabits disturbed ground, cultivated fields, roadsides, coastal dunes, and open sandy soils, favouring warm, dry conditions where it can germinate prolifically. <em>Lysimachia arvensis</em> is broadly distributed across Europe, Asia, North America including Canada and the United States, and South America including Brazil, reflecting both its native range and extensive spread through agriculture and human movement. It is assessed as Least Concern on the IUCN Red List given its wide distribution and abundance in disturbed habitats. Blue-flowered forms occasionally occur and were historically treated as a separate species. Biological traits such as average plant lifespan, maximum size, body mass, and detailed dietary or physiological parameters remain poorly documented in the scientific literature. The plant contains saponins and has a history of use in traditional medicine, though it is regarded as toxic to livestock in high quantities.