Foxglove

(Digitalis purpurea)


Family and Genus
Foxglove (scientific name Digitalis) is of the botanical family Scrophulariaceae (typically known as the figwort family), which consists mainly of herbs, but also includes shrubs and trees. Members of this family tend to be distinctly 2-lipped with irregular flowers and 4 stamens. The ovary is also distinct among the Scrophulariaceae plants: it is superior, of 2 cells joined together with a terminal style that is simple or bilobed. The fruit produced tends to be a capsule with many seeds per capsule cell, with a berry being quite rare. Members of the family total 22 genera, with around 4,500 species. Fewer then 10 of these genera boast flowers beautiful enough to be garden favorites. (Michael Allaby. "
Scrophulariaceae." A Dictionary of Plant Sciences. 1998. Encyclopedia.com. 28 Nov. 2009 <http://www.encyclopedia.com>.) Of the Digitalis genus, there are 6 known species, the most common being digitalis purpurea.
Digitalis Purpurea
Digitalis Purpurea


In its first year, foxglove plants produce only leaves. During the second year, these biennial plants each grow a straight stem without branches. Foxglove plants are known to reach up to 6 feet in height. (De Milto, Lori; Rebecca Frey. "
Foxglove." Gale Encyclopedia of Alternative Medicine. The Gale Group, Inc. 2005. Encyclopedia.com.
Parts of the Digitalis
Parts of the Digitalis
28 Nov. 2009 <
http://www.encyclopedia.com>.) When the 2-inch long, tubular, bell-shaped flowers bloom in the late spring and summer, they hang in bunches along the stem. The lower flowers open first and often droop after fully opening. The flowers that bloom next tend to lay on top of the older ones, especially on those heavily-flowering plants. Flowers can range in color from white to purple, with the purple/pink combination being the most common. (http://www.herbs2000.com/herbs/herbs_foxglove.htm)

Habitat and Geographic Distribution
The foxglove plant thrives in light, well-drained acidic soil that receives regular watering, is mixed with organic material, and is exposed to semi-shade. (Jody Thompson. “About foxglove.” Ehow.com. 28 November 2009. <http://www.ehow.com>.) However, it can also succeed in areas with full exposure to sunlight if the soil is moist or wet. These plants can tolerate cold temperatures fairly well (up to -25°C). It grows well in mixed woods, as it stimulates and is stimulated by the growth of neighboring plants and trees. (http://www.herbs2000.com/herbs/herbs_foxglove.htm) Foxglove is native to Western Europe, being found to naturally occur form Norway to Spain to Sardinia, although it has also been shown to grow in North American woodsy areas. It is often identified with the English countryside. It was first introduced into the United States as an ornamental plant. In its domesticated form, the most successful examples of propagation use stored seeds. These seeds typically take 2-4 weeks at 20°C to germinate inside a greenhouse. Once the plant begins to grow, each seedling is moved to its own pot, with each of these pots being planted outside at their permanent sites. (De Milto, Lori; Rebecca Frey. "Foxglove." Gale Encyclopedia of Alternative Medicine. The Gale Group, Inc. 2005. Encyclopedia.com. 28 Nov. 2009 <http://www.encyclopedia.com>.)
Distribution of Digitalis in the US
Distribution of Digitalis in the US


Human Use and Domestication


Medicinal Uses
Besides its ornamental use, the main reason for commercial cultivation of foxglove is for the useful glycosides it contains, notably digitoxin and digoxin. Foxglove was originally used to treat congestive heart failure and atrial fibrillation, as its cardiac glycosides help the muscles of the heart to contract, reduce the frequency of heartbeats, and lower the amount of oxygen the heart needs to work. The dried leaves, ripe dried seeds,
Full Grown Digitalis: stalk, leaves, and flowers
Full Grown Digitalis: stalk, leaves, and flowers
and fresh leaves of the one-year or two-year old plant are the parts that were originally used for medicine. In folk medicine, foxglove was first used in Ireland. Its use spread to Scotland, England, and then to central Europe. It was used to treat abscesses, boils, headaches, paralysis, and stomach ulcers. It was also applied directly to help wounds heal and to cure ulcers, but it has not been proven to be an effective treatment for any of these ailments. (De Milto, Lori; Rebecca Frey. "
Foxglove." Gale Encyclopedia of Alternative Medicine. The Gale Group, Inc. 2005. Encyclopedia.com. 28 Nov. 2009 <http://www.encyclopedia.com>.)

The introduction of the cardiac glycosides into medicine was primarily due to William Withering (1741–99), who studied medicine in Edinburgh and then practiced in Birmingham. It is said that he came across the power of the foxglove glycosides in his research on herbal medications which led him to know of an old woman in Shropshire who was a practitioner of folk medicine. She had cured a patient (of Withering) who was suffering from a complication of congestive heart failure that involves excessive fluid retention. Withering had expected the patient to die and was surprised by the cure the woman was able to come up with, so he studied the plant in his intrigue, eventually identifying the foxglove as the key ingredient. Withering would also find the poisonous nature of the foxglove enabled the herb to completely stop the human heart, even while it was also capable of shocking the heart into contraction. He thus spent a decade conducting precise experiments on the use of the herb to determine the proper dosage. (
http://www.herbs2000.com/herbs/herbs_foxglove.htm) Withering published his findings in An Account of Foxglove and Some of Its Medical Uses in 1785, in which he gave a full account of the botany, preparations, uses, and toxic effects. (Colin Blakemore and Sheila Jennett. "cardiac glycosides." The Oxford Companion to the Body. Oxford University Press. 2001. Encyclopedia.com. 28 Nov. 2009 <http://www.encyclopedia.com>.)

In present-day usage, foxglove is used as an ingredient in a class of heart drugs called digitalis. Digoxin (Lanoxin) is the most common drug made
The Most Common Drug Made from Digitalis
The Most Common Drug Made from Digitalis
from digitalis. Digitalis is usually taken orally, as a capsule, an elixir, or as a tablet. It can also be given as an injection. (De Milto, Lori; Rebecca Frey. "
Foxglove." Gale Encyclopedia of Alternative Medicine. The Gale Group, Inc. 2005. Encyclopedia.com. 28 Nov. 2009 <http://www.encyclopedia.com>.) Digitalis-like substances are found in a wide variety of plants and animals, but foxglove remains the main source for the drug used medically today. Chemically, digitalis is composed of a sugar (glycoside), a steroid, and a cyclic ester known as a lactone. Digitalis slows the pulse and the nerve impulses in the heart. By increasing the amount of calcium available to the heart muscle, it improves the force of each heartbeat and increases the amount of blood pumped. It is used in the treatment of congestive heart failure and cardiac arrhythmias. ("digitalis." The Columbia Encyclopedia, Sixth Edition. 2008. Encyclopedia.com. 28 Nov. 2009 <http://www.encyclopedia.com>.) The compounds present in foxglove also stimulate the production of urine in the kidneys, which brings about a reduction in the load of effort on the heart muscles because the total volume of blood in circulation has been lowered.
Chemical Structure of Digoxin
Chemical Structure of Digoxin


Precautions: Side Effects and Toxicity
Foxglove is no longer used as a heart medicine because the therapeutic dose and the lethal dose are very close. Because the level of cardiac glycosides in the plant varies according to where the plant is in its development, the safe dose is impossible to estimate except by an experienced physician who closely monitors the patient. (De Milto, Lori; Rebecca Frey. "Foxglove." Gale Encyclopedia of Alternative Medicine. The Gale Group, Inc. 2005. Encyclopedia.com. 28 Nov. 2009 <http://www.encyclopedia.com>.) Foxglove is, however, a useful example of the importance of standardization in testing the effectiveness and possible toxicity of today's popular herbal medicines. Its sap, flowers, seeds, and leaves are all poisonous. The leaves, even when dried, contain the largest amount of cardiac glycosides, and the upper leaves of the stem are more dangerous than the lower leaves. Foxglove is most toxic just before the seeds ripen. It tastes spicy or bitter.

When improperly used, foxglove is deadly: it can make the heart stop or cause a person to suffocate. All parts of the plant are poisonous, and because the therapeutic dose and the lethal dose are very close, an overdose can occur quickly with devastating effects. (Jody Thompson. “About foxglove.” Ehow.com. 28 November 2009. <http://www.ehow.com>.) Reaching a toxic level of foxglove interferes with the heart's normal electrical rhythms: it can make the heart beat too slowly or it can cause dangerous rapid heartbeats. Overdose can cause diarrhea, headache, loss of appetite, and vomiting. In the central nervous system, foxglove can cause confusion, depression, drowsiness, hallucinations, psychoses, vision problems, and death. What is particularly disturbing about these signs of overdose is that they are the exact same possible side effects (aside from death). Thus, it cannot be said definitively whether a person suffering from these symptoms has been overdosed or is simply experiencing the normal side effects of the medicine. The use of digitalis can also increase the toxicity of other cardioactive drugs. The risk of side effects are increased by dehydration, the use of diuretics, and one's personal sensitivity to the medicine may increase the risk of side effects from digoxin. The risk of cardiac arrhythmias is similarly increased when taking digitalis with amphetamines or diet pills, medicine for asthma or other breathing problems, or medicine for colds, sinus problems, hay fever, or other allergies. (De Milto, Lori; Rebecca Frey. "
Foxglove." Gale Encyclopedia of Alternative Medicine. The Gale Group, Inc. 2005. Encyclopedia.com. 28 Nov. 2009 <http://www.encyclopedia.com>.)


History and Folklore


Among all the older, traditional medicinal plants, foxglove is considered to be among "the loveliest, the most significant, the best known and even the most lethal".(http://www.herbs2000.com/herbs/herbs_foxglove.htm) For these reasons, the plant has become thoroughly entrenched in a variety of cultures, accumulating a number of different names throughout folklore and history, each with its own particular origin and meaning. This potent plant was so widely-known, often for its darker capabilities, that it made it into the writings of some of the most famous poets:

My poor Babe
Was crying, as I thought, crying for bread

Foxglove: A Potent Plant
Foxglove: A Potent Plant

When I had none to give him; whereupon,

I put a slip of foxglove in his hand,

Which pleased him so, that he was hushed at once:

When, into one of those same spotted bells

A bee came darting, which the Child with joy

Imprisoned there, & held it to his ear,

And suddenly grew black, as he would die."
- William Wordsworth


In England, the name “folk's glove" is an allusion to the traditional belief in fairy folk, who were said to inhabit woodsy areas where the foxglove is most common. Foxgloves have distinct spots on the flowers, and these spots were said to mark the places where woodland elves had placed their fingers, as a warning of the plant's poisonous nature. (http://www.herbs2000.com/herbs/herbs_foxglove.htm) Fairies were also believed by some to wear the flower-thimbles on their fingers while working their magic, and to wear them as hats or petticoats, prompting poet Hartley Coleridge to write: "Were we like the Fays/That sweetly nestle in the foxglove bell." Such belief is reflected in the names Fairy Caps, Fairy Gloves, Fairy Thimbles, Fairy Herb, Fairybells, Fairy-fingers, Goblin Gloves, Fairy Petticoats, Fairyweed, or Folks' Gloves. (http://www.paghat.com/foxgloves.html)

The name ‘Revbielde” or "fox bell" is given to the plant in Norway, and this name comes from the Norwegian legend about bad fairies who supposedly gave this plant to a fox so as to enable the animal to quiet its footsteps while it was hunting for prey among the forests and villages. Some say it got its name because the glove-shaped flowers resembled gloved fingers and the name foxglove is an allusion to the white paws of the common red fox. (http://www.herbs2000.com/herbs/herbs_foxglove.htm) The recurring association with foxes lent it additional names including: Dog's Lugs, Dog's Fingers, Fox's Lugs, Fox-&-Leaves, Foxdock, Foxter, Foxies & Foxbell. (http://www.paghat.com/foxgloves.html)

The large furry leaves were said to resemble the fur of a fox, but some imagined a rabbit instead of a fox, hence the names Bunny Rabbits or Rabbit Mouth, and names that include the word "flops", such as Bunny Flops or Foxflops. (http://www.paghat.com/foxgloves.html)

The common idea that the flowers resemble the fingers of gloves lent the plant names like Dog's Fingers, Fingerhuts, & Fingerflowers. Due to its toxicity, such names came to include Dead Man's Bells, Dead Men's Fingers, Deadmen's Thimbles, Dead Man's Bellows, Bloody Fingers, Bloodybells, & Bloody Man's Fingers. (http://www.paghat.com/foxgloves.html) The name Digitalis also literally refers to fingers probably because of a German name for the plant (fingerhut) which translates as "thimble." (Jody Thompson. “About foxglove.” Ehow.com. 28 November 2009. <http://www.ehow.com>.) The name "dead man’s thimbles" refers to the foxglove in Ireland as an reference to the harmful juice that comes from the plant. (http://www.herbs2000.com/herbs/herbs_foxglove.htm)
At the same time, because of their healing properties, foxglove plants are also known as Virgin's Gloves or Gloves of Our Lady. The names Lady's Fingers, Lady's Gloves, Lady's Slipper, or Lady's Thimbles had divine associations with the spiritual mother of the world, and then came to encompass Mary the Mother of God once Christianity became entrenched in Europe. (http://www.paghat.com/foxgloves.html)
Foxgloves in Full Bloom
Foxgloves in Full Bloom

An association with midwifery probably gave rise to the names Granny's Gloves or Granny's Bonnets, and Witches' Gloves. This name is likely also a reference to William Withering discovering the potency of the herb from an unnamed midwife. Foxglove mythology also associates the flower with Juno (Hera) who learned midwife lore from the Goddess Flora, including a supernatural method of using foxgloves to induce pregnancy. The myth follows that Flora placed a foxglove blossom on her thumb, touched Juno on the tips of her breasts and on her belly, so that she became impregnated with Mars (who had no father). (http://www.paghat.com/foxgloves.html)

Foxglove flowers were also though to look like an animal's open mouth. Within the
doctrine of signatures this meant it must have some medicinal value in treatment of maladies of the mouth and throat. A variety of names reflect such association with the mouth: Throatwort, Rabbit's Mouth, Bunny Mouths, Tiger's Mouth, Duck's Mouth, Gap-Mouth, and Dragon's Mouth. (http://www.paghat.com/foxgloves.html)






References


Allaby, Michael. "Scrophulariaceae." A Dictionary of Plant Sciences. 1998. Encyclopedia.com. 28 Nov. 2009 <http://www.encyclopedia.com>

Colin Blakemore and Sheila Jennett. "
cardiac glycosides." The Oxford Companion to the Body. Oxford University Press. 2001. Encyclopedia.com. 28 Nov. 2009 <http://www.encyclopedia.com>

De Milto, Lori; Rebecca Frey. "
Foxglove." Gale Encyclopedia of Alternative Medicine. The Gale Group, Inc. 2005. Encyclopedia.com. 28 Nov. 2009 <http://www.encyclopedia.com>

"digitalis." The Columbia Encyclopedia, Sixth Edition. 2008. Encyclopedia.com. 28 Nov. 2009 <http://www.encyclopedia.com>
Thompson, Jody. “About foxglove.” Ehow.com. 28 November 2009. http://www.ehow.com

http://www.herbs2000.com/herbs/herbs_foxglove.htm

http://www.paghat.com/foxgloves.html