''Digitalis purpurea'', the foxglove or common foxglove, is a poisonous
species
In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...
of
flowering plant
Flowering plants are plants that bear flowers and fruits, and form the clade Angiospermae (), commonly called angiosperms. The term "angiosperm" is derived from the Greek words ('container, vessel') and ('seed'), and refers to those plants th ...
in the
plantain
Plantain may refer to:
Plants and fruits
* Cooking banana, banana cultivars in the genus ''Musa'' whose fruits are generally used in cooking
** True plantains, a group of cultivars of the genus ''Musa''
* ''Plantaginaceae'', a family of flowerin ...
family
Family (from la, familia) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its ...
Plantaginaceae
Plantaginaceae, the plantain family, is a large, diverse family of flowering plants in the order Lamiales that includes common flowers such as snapdragon and foxglove. It is unrelated to the banana-like fruit also called "plantain." In older cl ...
,
native
Native may refer to:
People
* Jus soli, citizenship by right of birth
* Indigenous peoples, peoples with a set of specific rights based on their historical ties to a particular territory
** Native Americans (disambiguation)
In arts and entert ...
to and widespread throughout most of
temperate
In geography, the temperate climates of Earth occur in the middle latitudes (23.5° to 66.5° N/S of Equator), which span between the tropics and the polar regions of Earth. These zones generally have wider temperature ranges throughout t ...
Europe. It has also
naturalised
Naturalization (or naturalisation) is the legal act or process by which a non-citizen of a country may acquire citizenship or nationality of that country. It may be done automatically by a statute, i.e., without any effort on the part of the i ...
in parts of North America and some other temperate regions. The plant is a popular garden subject, with many
cultivar
A cultivar is a type of cultivated plant that people have selected for desired traits and when propagated retain those traits. Methods used to propagate cultivars include: division, root and stem cuttings, offsets, grafting, tissue culture, ...
s available. It is the original source of the heart medicine
digoxin
Digoxin (better known as Digitalis), sold under the brand name Lanoxin among others, is a medication used to treat various heart conditions. Most frequently it is used for atrial fibrillation, atrial flutter, and heart failure. Digoxin is on ...
(also called digitalis or digitalin). This
biennial plant
A biennial plant is a flowering plant that, generally in a temperate climate, takes two years to complete its biological life cycle.
Life cycle
In its first year, the biennal plant undergoes primary growth, during which its vegetative structures ...
grows as a rosette of leaves in the first year after sowing, before flowering and then dying in the second year (i.e. it is
monocarpic
Monocarpic plants are those that flower and set seeds only once, and then die.
The term is derived from Greek (''mono'', "single" + ''karpos'', "fruit" or "grain"), and was first used by Alphonse de Candolle. Other terms with the same meaning are ...
). It generally produces enough seeds, however, so that new plants will continue to grow in a garden setting.
Description
''Digitalis purpurea'' is an
herbaceous
Herbaceous plants are vascular plants that have no persistent woody stems above ground. This broad category of plants includes many perennials, and nearly all annuals and biennials.
Definitions of "herb" and "herbaceous"
The fourth edition of t ...
biennial
Biennial means (an event) lasting for two years or occurring every two years. The related term biennium is used in reference to a period of two years.
In particular, it can refer to:
* Biennial plant, a plant which blooms in its second year and th ...
or short-lived perennial plant. The leaves are spirally arranged, simple, long and broad, and are covered with gray-white pubescent and glandular hairs, imparting a woolly texture. The foliage forms a tight rosette at ground level in the first year.
The flowering stem develops in the second year, typically tall, sometimes longer. The flowers are arranged in a showy, terminal, elongated cluster, and each flower is tubular and pendent. The flowers are typically purple, but some plants, especially those under cultivation, may be pink, rose, yellow, or white. The inside surface of the flower tube is heavily spotted. The flowering period is early summer, sometimes with additional flower stems developing later in the season. The plant is frequented by bees, which climb right inside the flower tube to gain the
nectar
Nectar is a sugar-rich liquid produced by plants in glands called nectaries or nectarines, either within the flowers with which it attracts pollinating animals, or by extrafloral nectaries, which provide a nutrient source to animal mutualists ...
within.
The fruit is a
capsule which splits open at maturity to release the numerous tiny 0.1-0.2 mm
seed
A seed is an embryonic plant enclosed in a protective outer covering, along with a food reserve. The formation of the seed is a part of the process of reproduction in seed plants, the spermatophytes, including the gymnosperm and angiospe ...
s.
Subspecies and hybrids
*''Digitalis purpurea'' subsp. ''purpurea'' – most of Europe and
Macaronesia
Macaronesia (Portuguese: ''Macaronésia,'' Spanish: ''Macaronesia'') is a collection of four volcanic archipelagos in the North Atlantic, off the coasts of Africa and Europe. Each archipelago is made up of a number of List of islands in the At ...
and widely introduced to other parts of the world.
*''Digitalis purpurea'' subsp. ''amandiana ''
( Samp.) P.A.Hinz – northern
Portugal
Portugal, officially the Portuguese Republic ( pt, República Portuguesa, links=yes ), is a country whose mainland is located on the Iberian Peninsula of Southwestern Europe, and whose territory also includes the Atlantic archipelagos of ...
(specifically around the
Douro Basin
The Douro (, , ; es, Duero ; la, Durius) is the highest-flow river of the Iberian Peninsula. It rises near Duruelo de la Sierra in Soria Province, central Spain, meanders south briefly then flows generally west through the north-west part of ...
).
*''Digitalis purpurea'' subsp. ''mauretanica ''
(Humbert & Maire) A.M.Romo –
Morocco
Morocco (),, ) officially the Kingdom of Morocco, is the westernmost country in the Maghreb region of North Africa. It overlooks the Mediterranean Sea to the north and the Atlantic Ocean to the west, and has land borders with Algeria to ...
.
*''Digitalis purpurea'' subsp. ''toletana''
(Font Quer) P.A.Hinz – central
Spain
, image_flag = Bandera de España.svg
, image_coat = Escudo de España (mazonado).svg
, national_motto = ''Plus ultra'' (Latin)(English: "Further Beyond")
, national_anthem = (English: "Royal March")
, i ...
.
*
''Digitalis'' × ''fulva'' Lindl.
John Lindley FRS (5 February 1799 – 1 November 1865) was an English botanist, gardener and orchidologist.
Early years
Born in Catton, near Norwich, England, John Lindley was one of four children of George and Mary Lindley. George Lindley ...
1821 (hybrid formula:
''D. grandiflora'' × ''purpurea'').
![Digitalis purpurea - flower view01](https://upload.wikimedia.org/wikipedia/commons/a/a1/Digitalis_purpurea_-_flower_view01.jpg)
''Digitalis purpurea'' subsp. ''mariana'' is a
synonym
A synonym is a word, morpheme, or phrase that means exactly or nearly the same as another word, morpheme, or phrase in a given language. For example, in the English language, the words ''begin'', ''start'', ''commence'', and ''initiate'' are all ...
for
''D. mariana'' subsp. ''mariana'',
and ''D. purpurea'' subsp. ''heywoodii'' is a synonym for
''D. mariana'' subsp. ''heywoodii''.
[
''D. dubia'', a name used for populations of foxglove growing among calciferous rocks on shady cliff faces on the island of ]Majorca
Mallorca, or Majorca, is the largest island in the Balearic Islands, which are part of Spain and located in the Mediterranean.
The capital of the island, Palma, is also the capital of the autonomous community of the Balearic Islands. The Bal ...
, is now considered a synonym of ''D. minor'', but until recently it had been either considered to be a valid species (i.e. in the ''Flora Europaea
The ''Flora Europaea'' is a 5-volume encyclopedia of plants, published between 1964 and 1993 by Cambridge University Press. The aim was to describe all the national Floras of Europe in a single, authoritative publication to help readers identify ...
'' (1976), and the ''Euro+Med Plantbase'' (2011)), as well as classified as ''D. purpurea'' subsp. ''dubia'' in 1922, or ''Digitalis purpurea'' f. ''dubia'' by Spanish taxonomist
In biology, taxonomy () is the scientific study of naming, defining ( circumscribing) and classifying groups of biological organisms based on shared characteristics. Organisms are grouped into taxa (singular: taxon) and these groups are given ...
s in 1983.
Ecology
''Digitalis purpurea'' grows in acidic soil
Soil pH is a measure of the acidity or basicity (alkalinity) of a soil. Soil pH is a key characteristic that can be used to make informative analysis both qualitative and quantitatively regarding soil characteristics. pH is defined as the neg ...
s, in partial sunlight to deep shade, in a range of habitat
In ecology, the term habitat summarises the array of resources, physical and biotic factors that are present in an area, such as to support the survival and reproduction of a particular species. A species habitat can be seen as the physical ...
s, including open woods, woodland clearings, moorland and heath margins, sea-cliffs, rocky mountain slopes and hedge banks. It is commonly found on sites where the ground has been disturbed, such as recently cleared woodland, or where the vegetation has been burnt.
Larva
A larva (; plural larvae ) is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle.
The ...
e of the foxglove pug (''Eupithecia pulchellata
The foxglove pug (''Eupithecia pulchellata'') is a moth of the family Geometridae found in Europe. It was Species description, described by the English Entomology, entomologist James Francis Stephens in 1831.
Description
The wingspan is 18–22& ...
''), a moth, consume the flowers of the common foxglove for food. The caterpillars of this moth crawl into the newly opening flowers, one caterpillar to a flower. It then spins a silken web over the mouth of the flower, sealing it, and then proceeds to feed on the stamens and developing seeds. When the other uninfected flowers fall off, the corolla of the infected flowers remain on the plant, and the caterpillar then pupa
A pupa ( la, pupa, "doll"; plural: ''pupae'') is the life stage of some insects undergoing transformation between immature and mature stages. Insects that go through a pupal stage are holometabolous: they go through four distinct stages in their ...
tes in the flower. The species is uncommon, it has been recorded in Britain,[ Germany, Switzerland and Austria.][ Other species of ]Lepidoptera
Lepidoptera ( ) is an order (biology), order of insects that includes butterfly, butterflies and moths (both are called lepidopterans). About 180,000 species of the Lepidoptera are described, in 126 Family (biology), families and 46 Taxonomic r ...
have been recorded eating the leaves, including ''Mellicta athalia
The heath fritillary (''Melitaea athalia'') is a butterfly of the family Nymphalidae. It is found throughout the Palaearctic from western Europe to Japan, in heathland, grassland, and in coppiced woodland. Its association with coppiced woodland ...
'' and '' Xestia ashworthii'' in Britain, ''Eurodryas aurinia
The marsh fritillary (''Euphydryas aurinia'') is a butterfly of the family Nymphalidae. Commonly distributed in the Palearctic realm, Palearctic region, the marsh fritillary's common name derives from one of its several habitats, marshland. The p ...
'' in Romania, and ''Mellicta deione
''Melitaea'' is a genus of brush-footed butterflies (family (biology), family Nymphalidae). They are here placed in the tribe (biology), tribe Melitaeini of subfamily Nymphalinae; some authors elevate this tribe to subfamily rank.
As delimited ...
'' in Portugal.[
]
Genetics
The colours of the petals of the ''Digitalis purpurea'' are known to be determined by at least three genes that interact with each other.
The M gene determines the production of a purple pigment, a type of anthocyanin. The m gene does not produce this pigment. The D gene is an enhancer of the M gene, and leads it to produce a large amount of the pigment. The d gene does not enhance the M gene, and only a small amount of pigment is produced. Lastly, the W gene causes the pigment be deposited only in some spots, while the w gene allows the pigment to be spread all over the flower.
This combination leads to four phenotypes:
*M/_; W/_; _/_ = a white flower with purple spots;
*m/m; _/_; _/_ = an albino flower with yellow spots;
*M/_; w/w; d/d = a light purple flower;
*M/_; w/w; D/_ = a dark purple flower.
Cultivation
The plant is a popular ornamental, providing height and colour in late spring and early summer. Cultivated forms often show flowers completely surrounding the central spike, in contrast to the wild form, where the flowers only appear on one side. Numerous cultivars
A cultivar is a type of Horticulture, cultivated plant that people have selected for desired phenotypic trait, traits and when Plant propagation, propagated retain those traits. Methods used to propagate cultivars include: division, root and st ...
have been developed with a range of colours. Seeds are frequently sold as a mixture (e.g. Excelsior hybrids, in shades of white, pink and purple). Some strains are easily grown by the novice gardener, while others are more challenging. They may also be purchased as potted plants in the spring. The following selections have gained the Royal Horticultural Society
The Royal Horticultural Society (RHS), founded in 1804 as the Horticultural Society of London, is the UK's leading gardening charity.
The RHS promotes horticulture through its five gardens at Wisley (Surrey), Hyde Hall (Essex), Harlow Carr (Nort ...
's Award of Garden Merit
The Award of Garden Merit (AGM) is a long-established annual award for plants by the British Royal Horticultural Society (RHS). It is based on assessment of the plants' performance under UK growing conditions.
History
The Award of Garden Merit ...
:
*Camelot Series:
**'Camelot Cream'
**'Camelot Lavender'
**'Camelot Rose'
**'Camelot White'
*Dalmatian Series:
**'Dalmatian Crème'
**'Dalmatian Peach'
**'Dalmatian White'
*''D.'' × ''mertonensis'' (the strawberry foxglove)
*''D. purpurea'' f. ''alba''
*'Martina'
*'Pam's Choice'
*'The Shirley' (Gloxinioides group)
''Digitalis purpurea'' is hardy down to (USDA zones 4–9).
Toxicity
Due to the presence of the cardiac glycoside
Cardiac glycosides are a class of organic compounds that increase the output force of the heart and decrease its rate of contractions by inhibiting the cellular sodium-potassium ATPase pump. Their beneficial medical uses are as treatments for co ...
digitoxin
Digitoxin is a cardiac glycoside used for the treatment of heart failure and certain kinds of heart arrhythmia. It is a phytosteroid and is similar in structure and effects to digoxin, though the effects are longer-lasting. Unlike digoxin, w ...
, the leaves, flowers and seeds of this plant are all poison
Poison is a chemical substance that has a detrimental effect to life. The term is used in a wide range of scientific fields and industries, where it is often specifically defined. It may also be applied colloquially or figuratively, with a broa ...
ous to humans and some animals and can be fatal if ingested.
The main toxins in ''Digitalis'' spp. are the two chemically similar cardiac glycosides
Cardiac glycosides are a class of organic compounds that increase the output force of the heart and decrease its rate of contractions by inhibiting the cellular sodium-potassium ATPase pump. Their beneficial medical uses are as treatments for co ...
: digitoxin and digoxin
Digoxin (better known as Digitalis), sold under the brand name Lanoxin among others, is a medication used to treat various heart conditions. Most frequently it is used for atrial fibrillation, atrial flutter, and heart failure. Digoxin is on ...
. Like other cardiac glycosides, these toxins exert their effects by inhibiting the ATPase
ATPases (, Adenosine 5'-TriPhosphatase, adenylpyrophosphatase, ATP monophosphatase, triphosphatase, SV40 T-antigen, ATP hydrolase, complex V (mitochondrial electron transport), (Ca2+ + Mg2+)-ATPase, HCO3−-ATPase, adenosine triphosphatase) are ...
activity of a complex of transmembrane proteins that form the sodium potassium ATPase
Sodium is a chemical element with the Symbol (chemistry), symbol Na (from Latin ''natrium'') and atomic number 11. It is a soft, silvery-white, highly reactive metal. Sodium is an alkali metal, being in group 1 element, group 1 of the ...
pump, ( Na+/K+-ATPase). Inhibition of the Na+/K+-ATPase in turn causes a rise not only in intracellular Na+, but also in calcium, which in turn results in increased force of myocardial muscle contractions. In other words, at precisely the right dosage, ''Digitalis'' toxin can cause the heart to beat more strongly. However, digitoxin, digoxin and several other cardiac glycosides, such as ouabain, are known to have steep dose-response curves, i.e., minute increases in the dosage of these drugs can make the difference between an ineffective dose and a fatal one.
Symptoms of ''Digitalis'' poisoning include a low pulse rate, nausea, vomiting, and uncoordinated contractions of different parts of the heart, leading to cardiac arrest and finally death.
Medicinal use
Extracted from the leaves, this same cardiac glycoside digitoxin is used as a medication for heart failure
Heart failure (HF), also known as congestive heart failure (CHF), is a syndrome, a group of signs and symptoms caused by an impairment of the heart's blood pumping function. Symptoms typically include shortness of breath, excessive fatigue, a ...
. Its clinical use was pioneered by William Withering
William Withering FRS (17 March 1741 – 6 October 1799) was an English botanist, geologist, chemist, physician and first systematic investigator of the bioactivity of digitalis.
Withering was born in Wellington, Shropshire, the son of a surg ...
, who recognized it "reduced dropsy
Edema, also spelled oedema, and also known as fluid retention, dropsy, hydropsy and swelling, is the build-up of fluid in the body's tissue. Most commonly, the legs or arms are affected. Symptoms may include skin which feels tight, the area ma ...
", increased urine
Urine is a liquid by-product of metabolism in humans and in many other animals. Urine flows from the kidneys through the ureters to the urinary bladder. Urination results in urine being excretion, excreted from the body through the urethra.
Cel ...
flow, and had a powerful effect on the heart. During World War II
World War II or the Second World War, often abbreviated as WWII or WW2, was a world war that lasted from 1939 to 1945. It involved the vast majority of the world's countries—including all of the great powers—forming two opposin ...
, County Herb Committees were established to collect medicinal herbs when German blockades created shortages; this included ''Digitalis purpurea'' which was used to regulate heartbeat.
Gallery
Image:Digitalis Purpurea.jpg
Image:Digitalis_purpurea_alba_01-Juni.jpg, f.''albiflora''
Image:Fingerborgsblomma, closeup.jpg, Close-up of flower
Image:Foxglove -- Digitalis purpurea.jpg, Close-up of white
Image:Foxglove - Digitalis purpurea.jpg, Close-up of light purple
Image:Digitalis purpurea 'Primrose Carousel' Flower Closeup 1200px.jpg, Flower close-up
Image:Digitalis purpurea 'Primrose Carousel' Leaves 1100px.jpg, Leaves
File: Digitalis seed 2.JPG, Young plant a few weeks old
File:Digitalis_purpurea_004.JPG, Giant flower demonstrating pseudo- peloria
File:Bysedd y cwn ger Solfach - Foxgloves near Solva, Sir Benfro Pembrokeshire, Wales 10.jpg, Detail
See also
* List of poisonous plants
Plants that produce toxins are referred to as poisonous plants. Plants that cause irritation on contact are also described as "poisonous".
The toxins in poisonous plants affect herbivores, and deter them from consuming the plants. Plants cannot ...
References
Bibliography
Flora Europaea: ''Digitalis purpurea''
Ecological flora of the British Isles: ''Digitalis purpurea''
Purple Foxglove
USDA Invasive Plants of the US
External links
Video footage of peloric Digitalis purpurea
{{Authority control
Biennial plants
purpurea
Garden plants
Medicinal plants of Europe
Plants described in 1753
Taxa named by Carl Linnaeus
Taxobox binomials not recognized by IUCN
Poisonous plants