Botanical name: Lysimachia arvensis subsp. arvensis Family: Primulaceae (Primrose family)
Synonyms: Anagallis arvensis L.
Scarlet pimpernel has weak sprawling stems growing to about 50 cm long, sometimes rooting at the nodes. Leaves are opposite, entire, stalkless, ovate, up to 2 cm long, 1.3 cm broad, stem-clasping or not, with brown speckles below, variously pubescent. The small orange or red flowers are produced in the leaf axils from spring till autumn. The petal margins are somewhat crenate and have small glandular hairs. Blue Pimpernel is a closely related subspecies. The Blue Pimpernel and the Scarlet Pimpernel both are often called shepherd's weather glass or shepherd's clock because the flowers close before sunset or if it is about to rain. These brightly colored flowers appear as bright dots in the field, which dramatically "disappear" when the flowers close, if the sky is overcast or the sun is about to set. Closed flowers are quite hard to notice because of their dull color.
Identification credit: Gurcharan Singh
The flower labeled Scarlet Pimpernel is ...