Many years ago I was first introduced to a scarlet pimpernel (Lysimachia arvensis) as the alias of Sir Percy Blackeney in the book “The Scarlet Pimpernel”. Published in 1905, this first novel in a series by Baroness Emma Orczy takes place in the Reign of Terror after the French Revolution. Sir Blackeney was involved in rescuing French aristocrats and used a single scarlet pimpernel as his symbol.
Today scarlet pimpernels are considered invasive weeds. Native to Eurasia, this annual member of the Primrose Family has been naturalized worldwide and is found in all Lower 48 States except North Dakota and Wyoming.
Scarlet pimpernel plants have weak, sprawling stems and display a low-growing, creeping habit. The opposite leaves are simple, egg-shaped and have an entire edge. The leaves are opposite or may be arranged in whorls.
The flower color is variable and the petals can be white, pink to red, orange or blue to purple. Very confusing for identification unless one knows how variable the color can be! The flowers grow in leaf axils on long, thread-like, curved pedicels (stalks). The five petals are fused to form a tube with spreading lobes. There are four or five stamens. At the end of the first day of flowering the petals close, triggering self-fertilization of any flowers not already fertilized.
Fruits are dry capsules which split open when ripe, scattering seeds with the aid of wind or rain.
Scarlet pimpernel is toxic to animals causing gastroenteritis and even death if eaten in sufficient quantity. Fortunately the plant is bitter and livestock usually avoid eating it unless the area is overgrazed. Some insects are killed by scarlet pimpernel.
In folk medicine scarlet pimpernel was used as an antidepressant, expectorant and as a treatment for mental illness, depression, ulcerative wounds and rashes.
Scarlet pimpernel flowers open only in bright sunlight and close at night and in overcast conditions leading to the colloquial names poorman’s barometer and shepherd’s weather glass, among others. Anagallis arvensis is a synonym for L. arvensis.
These specimens were collected along the Turtle Bay Loop Trail and the Churn Creek Trails in Redding CA (Shasta County).