Anagallis Arvensis

Scarlet pimpernel (Anagallis arvensis; also known as red pimpernel, red chickweed, poorman's barometer, poor man's weather-glass, shepherd's weather glass or shepherd's clock) is a low-growing annual plant found in Europe, Asia and North America. Scarlet pimpernel flowers are open only when the sun shines.

Although traditionally included in the family Primulaceae, the genus Anagallis is now considered to be better placed within the related family Myrsinaceae. In the APG III system, Primulaceae is expanded to include Myrsinaceae, thus Anagallis is in Primulaceae sensu lato.

This common European plant is generally considered a weed and is an indicator of light soils.

It is most well known for being the emblem of the fictional hero The Scarlet Pimpernel.