Symphytum officinale | |
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Scientific classification ![]() | |
Kingdom: | Plantae |
Clade: | Tracheophytes |
Clade: | Angiosperms |
Clade: | Eudicots |
Clade: | Asterids |
Order: | Boraginales |
Family: | Boraginaceae |
Genus: | Symphytum |
Species: | S. officinale |
Binomial name | |
Symphytum officinale | |
Synonyms | |
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Symphytum officinale is a perennial flowering plant in the family Boraginaceae. Along with thirty four other species of Symphytum, it is known as comfrey (from the Latin confervere to 'heal' or literally to 'boil together', referring to uses in ancient traditional medicine). Internal or long-term topical use of comfrey is discouraged due to its strong potential to cause liver toxicity. [1]
To differentiate it from other members of the genus Symphytum, this species is known as common comfrey [2] or true comfrey. Other English names include boneset, knitbone, consound, and slippery-root. [3]
It is native to Europe, growing in damp, grassy places. It is found throughout Ireland and Britain on river banks and ditches. It occurs in North America as an introduced species and weed. The flowers are mostly visited by bumblebees. [4]
Over centuries, comfrey was cultivated in Asia, Europe, and the United Kingdom as a vegetable and herbal medicine. [1] [5] [6] Its early common names, knitbone or boneset, reflect its historical use by poultices of leaves and roots to treat sprains, bruises or bone fractures. [1] [5] Also the roots could be mashed then packed around a broken limb, when dried they formed a hardened 'plaster cast'. [7]
Comfrey is found in moist grasslands or along riverbanks and ditches in western Asia, Europe, and North America. [6] It is a perennial herb that is cold hardy down to −35 °C (−31 °F) and drought-tolerant. The plant can grow 1–5 feet (0.3–1.5 m) tall [8] with branched, strongly winged stems. The root system has a pronounced, deep-reaching (up to 1.8 metres [9] ) taproot. The internally white roots are covered with black bark. Above ground the plant is covered in long, downward-pointing, tapering hairs that are bristly on the stems and softer on the leaves. Along the erect stems grow large simple, mostly stalked leaves in an alternate pattern. They are oval-lanceolate and 4 to 25 centimetres long. In the upper parts they are narrower, without stalks, and with margins that extend down the stems. The chromosome count is 2n = 24, 26, 36, 40, 48 or 54. [9]
The plant flowers from May to June with forked cymes that are initially coiled and later open out. [7] They bear two rows of hermaphrodite flowers on nodding stalks that are 2 to 6 millimetres long. [10] The small flowers measure 8–20 millimetres in length and 12 to 18 millimetres across the corolla. The flowers are radially symmetrical with five equal petals that are fused into a tubular or narrowly bell-shaped corolla with pointed, recurved teeth that are 2 millimetres long. Petals come in mainly two colours – typically cream to yellow or pink to purplish. Inside are 5 stamens and 1 stigma. The calyx has a tubular segment of about 2 millimetres and narrow, pointed teeth of about 4 millimetres. The fruits are segmented into 4 egg-shaped, shiny black nutlets that are 5–6 millimetres long. The plant produces significant nectar when compared to other UK plants tested. [11] Although, it has a long tube, meaning only insects with long tongues can reach the nectar, some bees have been known to bite into the side of the flower to access the nectar – a foraging behaviour known as nectar robbing. [7]
With S. × uplandicum, leaf bases are not decurrent, stem internodes are not winged, and the surfaces of the seeds are brown, dull, and finely granular instead of shiny black. [12] Additionally, Symphytum × uplandicum is generally more bristly, flowers later (between June and August), [7] and its flowers tend to be more blue or violet. [13]
The latin name epithet officinale refers to its use for medicinal preparations. The official first formal scientific species description appeared in 1753 in Species Plantarum by Carl Linnaeus, Tomus I, page 136. [14]
Subspecies include subsp. uliginosum (A. Kern.) Nyman (syn. S. uliginosum auct. non Kern., S. tanaicense), subsp. officinale, and subsp. bohemicum (F. W. Schmidt) Čelak (syn. S. bohemicum).
A common hybrid is formed between Symphytum officinale and S. asperum , Symphytum × uplandicum, also known as Blue Comfrey, [7] or Russian comfrey, which is widespread in the British Isles, interbreeds with S. officinale, and represents the economically most important kind of comfrey. [15]
In folklore, Symphytum officinale roots were used in traditional medicine internally (as a herbal tea or tincture) or externally (as ointment, compresses, or alcoholic extract) for treatment of various disorders. [1] [6] [16] John Gerard, an English herbalist (1545–1612), mentions "the slimie substance of the roote made in a possett of ale" would help back pains.[ citation needed ] Poultices may be used with the intent to heal broken bones, giving it the name "knitbone". [1]
A 2013 review of clinical studies assessing the possible effect of comfrey on osteoarthritis found the research quality was too low to allow conclusions about its efficacy and safety. [17] In Europe as of 2015, there were no comfrey products for oral use, and those for topical uses to treat bruises or joint pain were evaluated as having risk of liver toxicity. [5]
Comfrey is mildly toxic. Like most Boraginaceae, it contains pyrrolizidine alkaloids which are toxic compounds readily absorbed via the stomach or skin, and have potential to increase the risk of fatal liver toxicity. [1] [5] [18] In 2001, the US Food and Drug Administration and Federal Trade Commission banned the sale of comfrey products for internal use and use on open wounds due to its potential toxicities. [19] [20] A 2018 review on pyrrolizidine alkaloids present in comfrey indicated widespread potential toxicity to humans and livestock, and the opportunity for drug development from these compounds. [21]
Herbal teas, also known as herbal infusions and less commonly called tisanes, are beverages made from the infusion or decoction of herbs, spices, or other plant material in hot water; they do not usually contain any true tea. Often herb tea, or the plain term tea, is used as a reference to all sorts of herbal teas. Many herbs used in teas/tisanes are also used in herbal medicine. Some herbal blends contain true tea.
Jacobaea vulgaris, syn. Senecio jacobaea, is a very common wild flower in the family Asteraceae that is native to northern Eurasia, usually in dry, open places, and has also been widely distributed as a weed elsewhere.
Symphytum is a genus of flowering plants in the borage family, Boraginaceae, known by the common name comfrey.
Borage, also known as starflower, is an annual herb in the flowering plant family Boraginaceae native to the Mediterranean region. Although the plant contains small amounts of pyrrolizidine alkaloids, some parts are edible and its seeds provide oil.
Tussilago farfara, commonly known as coltsfoot, is a plant in the tribe Senecioneae in the family Asteraceae, native to Europe and parts of western and central Asia. The name "tussilago" is derived from the Latin tussis, meaning cough, and ago, meaning to cast or to act on. It has had uses in traditional medicine, but the discovery of toxic pyrrolizidine alkaloids in the plant has resulted in liver health concerns.
Petasites hybridus, also known as the butterbur, is a herbaceous perennial flowering plant in the family Asteraceae that is native to Europe and northern Asia.
Lithospermum officinale, or common gromwell or European stoneseed, is a flowering plant species in the family Boraginaceae, native to Eurasia. It is the host plant for caterpillars of the monophagous moth Ethmia dodecea.
Veratrum is a genus of flowering plants in the family Melanthiaceae. It occurs in damp habitats across much of temperate and subarctic Europe, Asia, and North America.
Eupatorium cannabinum, commonly known as hemp-agrimony, or holy rope, is a herbaceous plant in the family Asteraceae. It is a robust perennial native to Europe, NW. Africa, Turkey, Syria, Iran, Iraq, Jordan, the Caucasus and Central Asia. It is cultivated as an ornamental and occasionally found as a garden escape in scattered locations in China, the United States and Canada. It is extremely attractive to butterflies, much like buddleia.
Pyrrolizidine alkaloids (PAs), sometimes referred to as necine bases, are a group of naturally occurring alkaloids based on the structure of pyrrolizidine. Their use dates back centuries and is intertwined with the discovery, understanding, and eventual recognition of their toxicity on humans and animals.
Ageratum conyzoides is native to Tropical America, especially Brazil, and is an invasive weed in many other regions. It is an herb that is 0.5–1 m. high, with ovate leaves 2–6 cm long, and flowers are white to mauve.
Cynoglossum officinale is a herbaceous plant of the family Boraginaceae.
Anchusa officinalis, also knowns as common bugloss or common alkanet, is a species of flowering plant in the borage family. It is native to Europe and small parts of western Asia, but has been escaped from cultivation to grow in additional locations in Europe and the Americas. The flowers are noted for their popularity with bumblebees due to a large nectar flow. The plants have been used in traditional medicines, but were falling out of favor by the early 1800s. They are still planted in gardens for their popularity with bees and their blue flowers.
Officinalis, or officinale, is a Medieval Latin epithet denoting organisms—mainly plants—with uses in medicine, herbalism and cookery. It commonly occurs as a specific epithet, the second term of a two-part botanical name. Officinalis is used to modify masculine and feminine nouns, while officinale is used for neuter nouns.
Symphytum tuberosum, the tuberous comfrey, is a species of Symphytum in the family Boraginaceae.
Senecionine is a toxic pyrrolizidine alkaloid isolated from various botanical sources. It takes its name from the Senecio genus and is produced by many different plants in that genus, including Jacobaea vulgaris. It has also been isolated from several other plants, including Brachyglottis repanda, Emilia, Erechtites hieraciifolius, Petasites, Syneilesis, Crotalaria, Caltha leptosepala, and Castilleja.
Russian comfrey or Quaker comfrey is a common hybrid between Symphytum officinale and S. asperum. It represents the economically most important kind of comfrey.
Riddelliine is a chemical compound classified as a pyrrolizidine alkaloid. It was first isolated from Senecio riddellii and is also found in a variety of plants including Jacobaea vulgaris, Senecio vulgaris, and others plants in the genus Senecio.
Andersonglossum virginianum, known as southern wild comfrey, is a flowering plant in the borage family native to North America. It is also sometimes called blue houndstongue.
Symphytum grandiflorum, the creeping comfrey, or running comfrey is a species of flowering plant in the family Boraginaceae. It is native to the Caucasus region, and introduced to various locales in Europe as a garden escapee. A deer-tolerant perennial, it is hardy in USDA zones 5 through 8, and is recommended for borders and shady situations. The unimproved species and a number of cultivars are commercially available. Also, it has been crossed with Russian comfrey to produce the multi-cross hybrid Hidcote comfrey ), of which a range of ornamental cultivars are available.