Scarlet Pimpernel (Poor Man’s Weatherglass)

Anagallis arvensis (Lysamachia arvensis)


Photo of scarlet pimpernel flower and plant
Joseph M. DiTomaso, University of California-Davis,

Primulaceae (Primroses)


A tender annual, branched from the base, with square stems. Flowers terminal and arising singly on long stems from leaf axils; petals united at base as a very short tube, deeply 5-lobed; less than ½ inch wide; scarlet or brick red, rarely white or bluish. Blooms May-September. Leaves opposite, stalkless, ovate, with dots underneath, with or without hairs, to ¾ inch long. Fruit a tiny, round capsule that opens its “lid” to disperse seeds.


Height: to about 6 inches.

Habitat and conservation

Found in fields, pastures, waste places, rights-of-way, and other disturbed sites, usually in moist soils. This plant can develop roots at the stem nodes and spread to form a mat. A native of Eurasia, this plant has been spread all over the world where the climate is suitable.

image of Scarlet Pimpernel Poor Man’s Weatherglass distribution map
Distribution in Missouri

Occurs in central, east-central, and southern Missouri.


The name "pimpernel" is a form of the original Latin name for this plant. In the early 1900s, a novel, stage play, and, later, musicals, movies, and TV shows, set in France during the Reign of Terror, depicted a fictional masked hero called "The Scarlet Pimpernel." The mysterious, dashing hero signs his letters only with a drawing of this little red flower, so common in Europe.

Human connections

This plant has a long history as a medicinal herb that goes back to the Greek scholars Pliny and Dioscorides. Over the centuries and in various countries, it has been used as a remedy for poor complexion, depression, rabies, weak vision, hard-to-remove splinters—and witchcraft!

Ecosystem connections

The flowers close around 4 p.m., or whenever clouds shade the sun. When the sun comes out again, they reopen—hence the common name "weatherglass." This adaption probably helps the plant maximize the amount of pollination that can occur while lengthening the life of each flower.