Anagallis arvensis L.
An ascending annual or biennial, from 5 to 40 cm long. Stems 4-angled. Leaves opposite, ovate to elliptical, 1 to 2 cm long. Flowers 1 to 1.3 cm across, blue or scarlet, solitary in the leaf axils, on stalks 1 to 3 cm long. The fruiting capsules are about 5 mm diameter on curved stalks.
The flowers which readily open in sunlight and close if it becomes cloudy, are known as the Poor Man’s Weather Glass.
Local: The blue coloured form is very common and widespread throughout Gibraltar, excluding urban areas. The scarlet form is rare, only growing in limited numbers as a weed in cultivated plots around Gibraltar.
Global: Found throughout Europe.
Flowers from March, April, May to June.
Grows in clearings and waysides.
The plant contains poisonous chemicals and has been used medicinally in the past.