Not to be semantically confused with : Fox-and-Cubs [a flower belonging to a differing Family]
Hybridizes with : Straw Foxglove (Digitalis lutea) to produce Digitalis × fucata.
Due to a recent taxonomical reassessment, Foxglove has now been placed in the Plantain Family (Plantaginaceae) instead of the 'Figwort and Foxglove' Family (Scrophulariaceae) it used to belong to. This seems strange, as its appearance is nothing like any other member of the Plantain Family. [Your author can imagine that they will be changing their minds again later over this plant].
from a distance, a drift of Foxglove could be mistaken for one of Purple Loosestrife or Rosebay Willowherb
Uniquely identifiable characteristics.
Foxglove is biennial: in the first year just a large basal rosette of crinkled leaves form on the ground; in the second year a single flowering stalk rises bearing a spike of usually purple coloured tubular flowers. It then dies, but sheds seeds which repeat the process.
Foxglove was instrumental to the creation of modern day pharmacology. Because of the not infrequent deaths resulting from its use as a herbal treatment for dropsy (an aberrant accumulation of fluids in the tissues of the body) that William Withering, a biologist and botanist, investigated the medical properties of dried Foxglove leaves. He found that the constituents of Foxglove, whatever they were, exerted their effects on the heart, slowing the heart rate and strengthening the beat (a property that would be more gainfully employed in the treatment of heart failure), and that it was this action that was helping with the condition called dropsy. The heart beat, in being stronger, was stimulating the kidneys to clear the body and lungs of excess fluids. But the problem was that there was a very narrow window between the amount of leaves necessary to cure the patient and that which would kill him! Too much would stop the heart altogether. This is nowadays called a narrow therapeutic window, and it is preferable that drugs have as wide a therapeutic window as is possible. Carefully measured amounts were found to be necessary to effect a cure. It was this process whereby William led the way forward; from herbal medicine to pharmacology. Eventually the active principles in the leaves responsible for their effects on the heart were identified, isolated and purified to produce the modern drugs that we use today. William led the way in all this.
Foxglove is the County Flower of four counties in the UK: Argyll, Birmingham, Leicestershire and Monmouthshire.
Apparently, there are also many cultivated garden varieties of Foxgloves, many with the flowers all around the stem instead of all on one side. Perhaps these have also been bred to be less toxic(?).
A Protandrous flower is one in which the stamens shed pollen before the stigma is receptive. Examples being the flowers of Jacobs Ladder and Foxglove. A protandrous flower is first functionally male and afterwards functionally female, but not both at the same time. This is only one of the ways in which some plants try to protect themselves from self-fertilisation.
But in the case of Foxglove, where the flowers open from the bottom upwards in the long spike and there is a time when the fully opened females at the bottom are concurent with the freshly-opening males nearer the top. Pollinators often start from the bottom with the female flowers then work their way up to the males nearer the top, thus they have not pollinated any flowers on the plant. But when they move on to the next Foxglove plant they pollinate the female flowers at the bottom with pollen from a differing Foxglove, thus helping cross-pollination and hindering self-pollination.
The leaves and flowers contain the spiro-steroid, Digoxigenin, used in biotechnology and immunohistological diagnosis rather than as a drug. Digoxigenin resembles Convallotoxin, the digitalin-like poison found in Lily-of-the-Valley.
Two cardiac glycoside heart drugs can be obtained from Foxglove plants: Digitoxin and Digoxin. These are not alkaloids, for they contain no nitrogen atoms. Both Digitoxin and Digoxin are based on the steroidal compound Digoxigenin, the molecule shown above, with the addition of glycosides. Both affect the rhythm and strength of the heart beat and are used as treatments for arrhythmias and heart failure. Although the effects of Digoxin are longer lasting than those of Digitoxin, the former is now rarely used as treatment.
Because Foxglove contains these toxic drugs, it is dangerous to ingest any part of the plant. Symptoms of poisoning include nausea, vomiting, diarrhoea, visual disturbances, confusion, and heart arrhythmias. For serious cases of poisoning an antidote is available.
Several other similar cardiac glycosides are found in Foxglove, Gitalin, F-gitonin, Digitonin as well as the poisonous iridoid glucosides Lanatosides A-C.