My first introduction to the Scarlet Pimpernel was from the movie of the same name. I loved the movie and always thought the flower would be the most lovely and romantic thing. But it is truly a tiny wayside flower measuring about 1/4 of an inch across and growing in waste places and roadsides, it prefers sandy type soil.
It was first introduced from Europe where it was at one time used as a cure for melancholy. The leaves may cause a severe dermatitis.
The flower closes in the late afternoon and on cloudy days or in bad weather. Because of this, it was called "Poorman's Weatherglass" in England.