Anagallis arvensis L.—Scarlet pimpernel; pimpernel; poor man's weather-glass
FAMILY: Primulaceae—the Primrose Family
Members of this family have regular, perfect flowers with superior ovaries; flowers: 5-merous; petals: 5, fused; stamens: opposite and upon the petals; ovary: 1-celled; style: 1; fruit: a capsule; leaves: simple, without stipules.
PHENOLOGY: Pimpernel flowers from June throughout August.
DISTRIBUTION: Anagallis arvensis is a weed of diverse situations: roadsides, gardens, lawns, pastures, meadows, and waste places.
PLANT CHARACTERISTICS: Pimpernel is an herbaceous annual plant; stems: 4-angled; leaves: small, opposite, sessile, 1-2 cm, underside with minute 'pits.' and "spots"; flowers: scarlet to brick-red, solitary in the axils; corolla: deeply 5-parted, giving the appearance of separate petals, lobes twisted in bud; staminal filaments: hairy; fruit: capsule, upper half dropping away for seed dispersal (circumscissile); flowers: open only in fair weather, quickly closing at the approach of summer storms or during cloudy weather.
POISONOUS PARTS: All parts are to be considered poisonous.
SYMPTOMS: Leaves can cause contact dermatitis. Although ingestion of the plants may cause poisonings, well-documented cases of poisonings are rare. Sheep feeding tests produced death in 2 days at concentrations of 2% of the animal's weight; later in the growing season toxicity could not be demonstrated. Symptoms of toxicity included depression, anorexia, and diarrhea; lesions included kidney, heart, and rumen hemorrhaging, congestion of lungs, and a pale, crumbling liver. Loss of 6 calves was once reported.
POISONOUS PRINCIPLES: The toxin(s) remains unknown.
CONFUSED TAXA: There are no herbaceous annual plants with opposite leaves, scarlet flowers, and circumscissile capsules except Anagallis arvensis.
SPECIES OF ANIMALS AFFECTED: This plant is potentially poisonous to all species of animals.
OF INTEREST: Flowers are rarely white or sky-blue. Because flowers open and close in response to weather conditions, one of this plant's names is "poor man's weather-glass."