The name "Scarlet Pimpernel" was widely popularized by a novel of the French Revolution by Baroness Orczy, whose hero, Sir Percy Blakeney, used the flower as a trademark when he rescued victims from the Reign of Terror.
The petals fold up when skies darken before storms or at twilight, not opening again until morning light triggers their rebloom -- hence its other common name, poor-man's weather glass. A native of Europe and Asia, it is sparingly naturalized in parts of the United States.
Description of scarlet pimpernel: A plant whose low-spreading habit causes it to creep over the ground rather than grow upright, scarlet pimpernel's bright flowers provide a twinkling cloud of color. A blue form (A. a. caerulea) gives the same light, airy effect. It will rarely grow more than 4 to 5 inches high.
Growing scarlet pimpernel: Scarlet pimpernel thrives in full sun in ordinary garden soil, but favors sandy, well-drained conditions. Plant 6 inches apart after danger of frost has passed. It will continue blooming all summer.
Propagating scarlet pimpernel: Start new plants from seeds. Seeds germinate in about 18 days indoors at 60 degrees Fahrenheit and may be planted when the danger of frost has passed. They're easily grown by sowing seeds in the garden, then thinning plants to 6 inches apart. They also reseed.
Uses for scarlet pimpernel: Scarlet pimpernel is ideal for color in a rock garden. It also makes a good edging for paths or flower borders. Grown in pots on a sunny windowsill, it will continue flowering during fall and winter.
Scarlet pimpernel related species: A. monellii, which grows up to 1 foot high, can be grown as an annual. The flowers range from blue with red undersides to pink. A. tenella, from the moist soils of southern Europe, bears small, scarlet, bell-shaped flowers on longer stems.
Scientific name of scarlet pimpernel: Anagallis arvensis