Calendula (/kəˈlɛndjlə/), is a genus of about 15–20 species of annual and perennialherbaceousplants in the daisy familyAsteraceae that are often known as marigolds.:771 They are native to southwestern Asia, western Europe, Macaronesia, and the Mediterranean. Other plants are additionally known as marigolds, such as corn marigold, desert marigold, marsh marigold, and plants of the genus Tagetes. The genus name Calendula is a modern Latin diminutive of calendae, meaning "little calendar", "little clock" or possibly "little weather-glass". The common name "marigold" refers to the Virgin Mary. The most commonly cultivated and used member of the genus is the pot marigold (Calendula officinalis). Popular herbal and cosmetic products named 'calendula' invariably derive from C. officinalis.

Traditional and ancient uses

Calendula species have been used traditionally as culinary and medicinal herbs. The petals are edible and can be used fresh in salads or dried and used to colour cheese or as a replacement for saffron. A yellow dye has been extracted from the flowers.

Romans and Greeks used the golden calendula in a large number of rituals and ceremonies, at times wearing crowns or garlands made from the flowers. One of its nicknames is "Mary's Gold," referring to the flowers' use in early Catholic events in a few countries. Calendula flowers are sacred flowers in India and have been used to decorate the statues of Hindu deities after early times.

Calendula ointments are skin products used to treat minor cuts, burns, and skin irritation.

Chemistry

The flowers of C. officinalis contain flavonolglycosides, triterpene oligoglycosides, oleanane-type triterpene glycosides, saponins, and a sesquiterpeneglucoside.

Pharmacological effects

Calendula oil is still used medicinally. The oil of C. officinalis is used as an anti-inflammatory, an antitumor agent, and a remedy for healing wounds.

Plant pharmacological studies have suggested that Calendula extracts have antiviral, antigenotoxic, and anti-inflammatory properties in vitro. In herbalism, Calendula in suspension or in tincture is used topically for treating acne, reducing inflammation, controlling bleeding, and soothing irritated tissue. Limited evidence indicates Calendula cream or ointment is effective in treating radiation dermatitis. Topical application of C. officinalis ointment has helped to prevent dermatitis and pain; thus reducing the incidence rate of skipped radiation treatments in randomized trials.

Calendula has been used traditionally for abdominal cramps and constipation. In experiments with rabbit jejunum, the aqueous-ethanol extract of C. officinalis flowers was shown to have both spasmolytic and spasmogenic effects, thus providing a scientific rationale for this traditional use. An aqueous extract of C. officinalis obtained by a novel extraction method has demonstrated antitumor (cytotoxic) activity and immunomodulatory properties (lymphocyte activation) in vitro, as well as antitumor activity in mice.

Calendula plants are known to cause allergic reactions, and should be avoided throughout pregnancy.

Culinary use

Calendula species have been used in cooking for centuries. The flowers were a common ingredient in German soups and stews, which explains the nickname "pot marigold". The lovely golden petals were additionally used to add colour to butter and cheese. The flowers are traditional ingredients in Mediterranean and Middle Eastern dishes. Calendula tea provides health benefits, as well as being delicious.

Dye use

The beautiful flowers were once used as a source of dye for fabrics. By using different mordants, a variety of yellows, oranges and browns can be obtained.

Medicinal use

Ancient cultures recognised and used the healing properties of calendula. In a few of the earliest medical writings, calendula was recommended for treating ailments of the digestive tract. It was used to detoxify the liver and gall bladder. The flowers were applied to cuts and wounds to stop bleeding, prevent infection and speed healing. Calendula was additionally used for various women's ailments, and to treat a number of skin conditions. During the American Civil War, calendula flowers were used on the battlefields in open wounds as antihemorrhagic and antiseptic, and they were used in dressing wounds to promote healing. Calendula additionally was used in this way throughout World War I. Calendula has been historically significant in medicine in a large number of cultures, and it is still important in alternative medicine today.

Diversity

Group of flowers of Calendula arvensis in Israel.

Species include:

  • Calendula arvensis(Vaill.) L. – field marigold, wild marigold
  • Calendula denticulataSchousb. ex Willd.
  • Calendula eckerleiniiOhle
  • Calendula incanaWilld.
    • Calendula incana subsp. algarbiensis(Boiss.) Ohle
    • Calendula incana subsp. maderensis(DC.) Ohle – Madeiran marigold
    • Calendula incana subsp. maritima(Guss.) Ohle – sea marigold
    • Calendula incana subsp. microphylla(Lange) Ohle
  • Calendula lanzaeMaire
  • Calendula maritimaGuss. - sea marigold
  • Calendula maroccana(Ball) Ball
    • Calendula maroccana subsp. maroccana
    • Calendula maroccana subsp. murbeckii(Lanza) Ohle
  • Calendula meuseliiOhle
  • Calendula officinalisL. – pot marigold, garden marigold, ruddles, Scottish marigold
  • Calendula palaestinaBoiss.
  • Calendula stellataCav.
  • Calendula suffruticosaVahl
    • Calendula suffruticosa subsp. balansae(Boiss. & Reut.) Ohle
    • Calendula suffruticosa subsp. boissieriLanza
    • Calendula suffruticosa subsp. fulgida(Raf.) Guadagno
    • Calendula suffruticosa subsp. lusitanica(Boiss.) Ohle
    • Calendula suffruticosa subsp. maritima(Guss.) Meikle
    • Calendula suffruticosa subsp. monardii(Boiss. & Reut.) Ohle
    • Calendula suffruticosa subsp. tomentosaMurb.
  • Calendula tripterocarpaRupr.

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