Plant 242

Digitalis purpurea L. (Plantaginaceae)



The foxglove, with a tall spike of purple or purplish-pink flowers, grows wild in the British Isles and western Europe but is also grown as an ornamental; white forms sometimes occur. It was familiar to Jacob Bobart the Younger who preserved a specimen of foxglove in his herbarium in the seventeenth century. It is biennial, sometimes perennial. The name Digitalis is derived from the Latin for finger (digitus), which represents the form of the tubular flowers, somewhat shaped like fingers.

The inside of the flowers, which hang downwards, are mottled with dark coloured spots surrounded by a whitish background. The flowers at the bottom of the columnar spike open first. Bumblebees, which are effective pollinators, are particularly attracted to the flowers, which produce abundant nectar. The bees start by visiting lower flowers and then work their way up the flower spike before visiting another plant. The foxglove has adapted by flowers in the same inflorescence shedding pollen before the female part of the flower is receptive. This is an example of protandry that promotes cross-pollination within the species.

Although all parts of the foxglove are highly toxic and should not be eaten, the plant has important medicinal uses. It is the source of digitoxin, a cardiac glycoside, which in controlled doses acts as a heart stimulant. Its use as a medicine was first advocated by the physician William Withering in 1785 who had been experimenting with it on patients for the previous ten years. Withering gathered dried leaves at the time of flowering which were boiled in water, the resulting medicine being administered to patients. It was also used to treat dropsy. Since that time much research has taken place on the use of digitoxin and other Digitalis glycosides in the pharmaceutical world.

Drugs were in short supply in Britain during World War II leading to a governmental Vegetable Drugs Committee being set up. A coalition of medical experts and botanists worked with members of the public including Women's Institutes, Boy Scouts and Girl Guides, who were encouraged to gather, grow and harvest foxgloves. In 1941 a processing plant in Islip, Oxford, produced 350,000 doses of digitoxin, the raw material having been supplied by Oxfordshire Women's Institutes.

There are few references to foxglove use in literature but the first in a novel appears in George Eliot's Silas Marner (1861), when Silas cures Sally Oates with a preparation of the plant.

Further reading

Aronson JK 1985. An account of the foxglove and its medical uses 1785-1985. Oxford University Press.

Ayres PG 2015. Britain's green allies: medicinal plants in wartime. Matador.

Proctor M et al. 1996. The natural history of pollination. HarperCollins Publishers.

Serena Marner