pimpernel

noun

1. a plant belonging to the genus Anagallis, of the primrose family, especially A. arvensis (scarlet pimpernel), having scarlet or white flowers that close at the approach of bad weather.

noun

1. any of several plants of the primulaceous genus Anagallis, such as the scarlet pimpernel, typically having small star-shaped flowers
2. any of several similar and related plants, such as Lysimachia nemorum (yellow pimpernel)

n.c.1400, from Old French pimprenelle, earlier piprenelle (12c.) and directly from Medieval Latin pipinella name of a medicinal plant. This is perhaps from *piperinus “pepper-like” (so called because its fruits resemble peppercorns), a derivative of Latin piper “pepper” (see pepper (n.)); or else it is a corruption of bipinnella, from bipennis “two-winged.” The Scarlet Pimpernel was the code name of the hero in an adventure novel of that name published 1905.