Hypericum perforatum, commonly known asSt. John's wort (sometimesperforate St. John's wort orcommon St. John's wort), is aflowering plant in the familyHypericaceae. It is a hairless,perennial herb with woodyroots, yellowflowers marked by black glands, and leaves that appearperforated due totranslucent glands, producing thousands of seeds per plant.
H. perforatum is the type species of itsgenus, known for its historical use infolklore andtraditional medicine. Probably ahybrid between the closely relatedH. attenuatum andH. maculatum (imperforate St. John's wort) that originated inSiberia, the species hasspread worldwide. It can further hybridize with related species due to itsallopolyploid nature. It is native to much of Europe,West andCentral Asia, and parts of Africa and China and has been widely introduced elsewhere, thriving in well-drained,temperate habitats such as meadows, hillsides, and open woods with moderate rainfall and mild temperatures. It is a resilient,toxic, andinvasive plant thatreproduces sexually and vegetatively, supports specialized insectherbivores, suffers fromplant diseases, and poses ecological and agricultural threats in many parts of the world.
H. perforatum has been used for centuries in traditional medicine, especially for treatingwounds anddepression. To prepare it for use, the oil from its glands can be extracted or its above-ground parts can be dried and ground into a powder calledherba hyperici.H. perforatum exhibitsantidepressant effects comparable to drugs with fewerside effects for mild to moderate depression (for which it is approved in the European Union); however, it may interact with various medications by accelerating their metabolism.
Leaf showing translucent glands and dark glands near the edges
Hypericum perforatum is anherbaceousperennial plant with hairless (glabrous) stems and leaves.[1] The root of each plant is slender and woody with many small, fibrous small side roots and also extensive, creepingrhizomes.[2] Thecentral root grows to a depth of 0.6–1.5 metres (2 ft 0 in – 4 ft 11 in) into the soil depending on conditions.[3] The crown of the root is woody.[2]
Its stems are erect and branched in the upper section, and usually range from 0.3 metres to 1 metre in height.[3] The stems are woody near their base and look like they have segmented joints from thescars left behind after the leaves fall off.[4] The stems ofH. perforatum are rusty-yellow to rosy in color with two distinct edges and usually have bark that sheds near the base. The stems persist through the winter and sprout new growth with flower buds in the following year; first year growth does not produce flowers.[2]
It has leaves that attach onopposite sides of the stems without a stalk (sessile). The leaves vary in shape from being very narrow and almost grass-like (linear), to a rounded oval slightly wider at the base with a rounded tip or not much of a tip (elliptic), or even narrow with the widest portion towards the end of the leaf like a reversed lance point, but still long and narrow (oblanceolate).[2] The principle leaves range in length from 0.8 to 3.5 centimetres[1] and 0.31–1.6 centimetres in width.[2] Leaves borne on the branchessubtend the shortened branchlets. The leaves are yellow-green in color, with scatteredtranslucent dots of glandular tissue.[5][6] The dots are clearly visible when held up to the light, giving the leaves aperforated appearance.[7] The edges (margins) of the leaves usually have scattered black dots, often called dark glands, though sometimes they will appear away from the edges.[2][8] The odor of the plant is faint, but aromatic, resembling that of resins likebalsam. The taste of the plant is bitter and acrid.[1]
Blossom showing black colored dark glands at the edges of the petals
The flowers are conspicuous and showy, measuring about 1.5–2.5 cm (0.59–0.98 in) across, and are bright yellow with black dots along the edges of the petals.[2][9][10] Each of the flowers normally has five large petals and five smaller leaf-likesepals below them. The sepals are about 4–5 mm (0.16–0.20 in) in length, green in color, are shaped like the head of a spear (lanceolate shape) with a pointed tip, and the same clear and black glands as the leaves. The petals are significantly longer, 8–12 mm (0.31–0.47 in) in length, and have an oblong shape. They completely hide the sepals from the front side of the flower.[11] The many bright yellowstamens are united at the base into three bundles.[11] The stalk portion of the stamens, the filaments, vary in length and stick out in every direction from the center of the flower.[2] Thepollen grains are pale brown to orange in color.[12] Each flowering stem bears many flowers, between 25 and 100, and also is quite leafy.[11]
The fruit ofHypericum perforatum is a capsule 7–8 mm (0.28–0.31 in) in length containing the seeds in three valved chambers.[11][2] Seeds that are separated from the capsules have a much highergermination rate due to an inhibiting factor in the capsule itself.[3] The black andlustrous seeds are rough, netted with coarse grooves.[13] Each seed is about 1 mm (0.039 in) in size.[11] Each plant may produce an average of 15,000 to 34,000 seeds.[3]
Hypericum maculatum is visually similar toHypericum perforatum; however, its stems have four ridges instead of two and are also hollow. In addition, its leaves have fewer translucent glands and more dark glands.H. maculatum is native to the Old World but has also been introduced to North America.[3]
In North America several native species may be confused withHypericum perforatum.Hypericum anagalloides is a low-growing creeping plant with rounder leaves and fewer stamens.Hypericum boreale is a smaller plant with more delicate flowers.Hypericum canadense has smaller flowers with sepals that show between the petals.Hypericum concinnum has flowers with petals that bend backward at the tip and also has much narrower, gray-green leaves. Growing inriparian areas along rivers,Hypericum ellipticum has wider leaves with a more elliptic shape.Hypericum scouleri has leaves that are broader at the base and also thicker. All except forH. concinnum grow in environments that are generally more moist than whereH. perforatum is found.[3]
^Values given in brackets are IC50/EC50 depending on whether it is an inhibitory or inductive action the compound displays towards the biologic target in question. If it pertains to bacterial growth inhibition the value is MIC50
Hypericum perforatum was selected to be thetype species around which the genusHypericum is based because of its widecosmopolitan distribution; it is the most common species of the genus in many of the areas it is found, and is one of the most widely known plants among the St John's worts in folklore and medicine.[17]: 19 The current accepted placement ofH. perforatum within its genus can be summarized as follows:[21]: 62
Hypericum perforatum has achromosome count of 2n = 32. The likely reason for this is that the species is ahybrid between the very closely relatedH. maculatum subsp. immaculatum andH. attenuatum, which means it inherited sets of chromosomes from both parents and isallopolyploid. The two species almost certainly hybridized withinSiberia, Russia. The equation for this hybridization is:[17]
H. maculatum subsp.immaculatum (16) ×H. attenuatum (16)×2 =H. perforatum (32)
Hypericum ×desetangsii is a hybrid betweenH. perforatum andH. maculatum. It displays intermediate traits of the two species.
Because of its hybrid origins,Hypericum perforatum is one of the few species within its genus that is able to further hybridize with other species, specifically those withinH. ser.Hypericum. The hybrids that are descended fromH. perforatum can be triploid (3 sets of chromosomes) to hexaploid (6 sets), depending on the chromosome count of the second parent species and the ploidy of the specificH. perforatumgamete that is fertilized or is fertilizing. The triploid offspring exhibit and a mix of traits from the two parents and pass them on to their offspring; the tetraploids also have a mix of traits, but often do not pass on the traits of both parents; the pentaploids are rarely distinguishable fromH. perforatum. Because of this, after many generations of hybridization a wide range of traits on a spectrum between the two hybridizing species can be observed in the wild.[21]: 64
Thegenus nameHypericum is possibly derived from theGreek wordshyper (above) andeikon (picture), in reference to the tradition of hanging the plant over religiousicons in the home.[22] Thespecific epithetperforatum isLatin and refers to the perforated appearance of the plant's leaves.[13]
The common nameSt John's wort comes from the fact that its flowers and buds were commonly harvested at the time of theMidsummer festival, which was laterChristianized asSt John's Feast Day on 24 June. It was believed that harvesting the flower at this time made its healing and magical powers more potent. The herb would be hung on house and stall doors on St John's Feast Day to ward off evil spirits and to safeguard against harm and sickness to people and livestock. In other traditions it was burned in bonfires for the protection of crops along with other herbs believed to be magical.[23][24] Because of its supposed potency in warding off spirits, the plant was also known asfuga daemonum (loosely "demon-flight").[25] Many other similarly fanciful names have been used for it includingdevil's scourge,Lord God's wonder plant, andwitch's herb.[26] In medievalKent it was calledherbe Ion (Ion in this case referring to "John") as recorded in the poemThe Feate of Gardening.[27] Other local names forHypericum perforatum includebalm of the warrior's wound inSomerset,penny John inNorfolk,rosin rose inYorkshire, andtouch-and-heal inNorthern Ireland.[24] Locally in the United States, it may also be referred to asTipton-weed,goatweed, orKlamath weed.[28][29]
In the 21st century, any species of the genusHypericum can be referred to as St John's wort. Therefore, it is more accurate to callHypericum perforatum thecommon St John's wort orperforate St John's wort.[25][1]
Hypericum with flowers that have threepistils,ancipital stems, and obtuse leaves with pointed dots.
Linnaeus also noted the species' habitat in the "meadows of Europe" and gave a short account of previous mentions of the plant.[30] While Linnaeus' taxonomicpriority for this species is not in question, there are a number ofbotanical synonyms that were published in the early years of formalbotanical nomenclature. Gaterau publishedDescription des plantes qui croissent aux environs de Montauban in 1789 which described and called the speciesHypericum officinale, a name now considered to beillegitimate under the principle of priority. Likewise, the nameHypericum officinarum by the botanistHeinrich Johann Nepomuk von Crantz in 1763 also postdated Linnaeus' 1753 naming and description and is considered invalid.[31]
Hypericum perforatum exhibits a great deal of variability in its appearance across its distribution. Thus, determining the exact nature of itsinfraspecific taxa is difficult because of the many intermediate forms that exist.[21]: 88
H. perforatumsubspeciesperforatumStjep.-Vesel. is the type form of the species. It is distributed from the origin of the species in Siberia, west to central Europe, and east to northern Mongolia. The base changes as the plant grows from round to a broad wedge shape, and the seed capsulevittae are present throughout the plant's life cycle and are almost always narrow.
H. perforatumvarietyangustifoliumDC. is a variety of the species that is found in drier climates within the range of ssp.perforatum. It has leaves that look more like those of ssp.veronense, but they haveleaf stalks; the glands on the seed capsule are also distinct.[21]: 88
H. perforatum var.humileStranski can be found in parts of the southern Balkans. These plants possess smaller, more ring-shaped leaves and the seed capsules have flattishvesicles on their surface. These appear to be adaptations of ssp.perforatum in response to the mountainous habitats of the region.[21]: 89
H. perforatum ssp.songaricum is likely the most primitive after ssp.perforatum. Previously described as a variety byKarl Koch,Norman Robson elevated the taxon to subspecies in his monograph of the genus. The leaves are sessile and have a heart-shaped base that partially surrounds the stem.[21]: 89
H. perforatum var.gracile has smaller leaves and is found in western Kazakhstan, southern Russia, and southern Ukraine. In the drier areas of this range the variety exhibits a dull grey-green color on the underside of its leaves.[21]: 89
H. perforatum ssp.veronense can be found in the Caucasus, across the Middle East to Tajikistan, and along North Africa toMacaronesia. These plants have narrower leaves and display diagonal vittae on the seed capsules. Where it meets the distribution of ssp.perforatum the two subspecies hybridize regularly.[21]: 89
H. perforatum var.ellipticum retains the diagonal vittae of the subspecies but the leaves are not as narrow. The variety is distributed in areas with greater moisture such as in the mountainous areas of Turkmenistan.[21]: 89
H. perforatum ssp.chinense is found across most of China and was introduced into Japan (under the synonymH foliosissimumKoidz.). Both its leaves and flowers are smaller, and the flower clusters are smaller and more crowded on the ends of longer branches.[21]: 89
Hypericum perforatum is thought to be native to every nation in Europe, and is only absent from the far north such as north European Russia andSvalbard. It grows in parts of North Africa and is native to Morocco, Algeria, Tunisia, and Sudan.[31]
In theArabian Peninsula it only grows in parts of Saudi Arabia. It is present and native to all of the Western Asiaphytogeographic region from theAegean Islands and Turkey to Israel and Palestine in the west to Afghanistan in the east, only being absent from theSinai Peninsula. Just to the east of this area it is also native to Pakistan and the western Himalaya region of India.[31]
In the temperate parts of Asia,Hypericum perforatum is mostly absent from Siberia with the exception ofWestern Siberia, theAltai Region, and the warmest parts ofKrasnoyarsk Krai. It has also been introduced toIrkutsk andBuryatia. It is a native part of the flora of Central Asia, growing in all the formerSoviet republics. It also is known in almost every part of theCaucasus. In China it is native toXinjiang (in western China), central China, and southern China, but not to Inner Mongolia,Manchuria, orTibet. In the far east of Asia it has been introduced toPrimorye in Russia, Korea, and Japan.[31][32]
In North America, it is found in all of the continental US states except forUtah,Arizona,Florida, andAlabama. It has been introduced throughout much of Canada,[33] as well as inHawaii, Cuba, and Haiti.[31]
In South America, it is found in Argentina, Chile, Uruguay, theJuan Fernández Islands, and the moretemperate parts of Brazil in the southeast. In the southern parts of Africa it has become established in South Africa,Lesotho, andRéunion. In Australia it is found in the states ofSouth Australia,Tasmania,Victoria, andWestern Australia. It has been introduced to both the North and South Islands of New Zealand.[31]
The species can be found in a variety of habitats including open woods,meadows, grasslands,steppe, riverbanks, and stony or grassy hillsides and roadsides. It prefers dry habitats or areas with strongdrainage.[21]: 88 The species thrives in areas with at least 760 mm (30 in) of rainfall per year; however, its distribution is restricted by temperatures too low for seed germination or seedling survival: an absolute minimum of −3°C or an annual average of 9°C.[34] Altitudes greater than 1,500 m (4,900 ft), rainfall less than 500 mm (20 in), and daily mean temperatures greater than 24 °C (75 °F) are also considered limiting thresholds.[35]
St John's wort reproduces bothvegetatively andsexually. Depending on environmental and climatic conditions, and the age of the plant, St John's wort will alter the way it grows to promote survival. Summer rains are particularly effective in allowing the plant to grow vegetatively, followingdefoliation by insects or grazing.[35] St John's wort may also produce viableseeds without fertilization.[3] Its seeds can persist for decades while lying dormant underground in an ecosystem'ssoil seed bank, germinating after they are disturbed.[36][34]
H. perforatum is affected byphytoplasma diseases, and when infected withCandidatus phytoplasma fraxini it shows visible symptoms, including yellowing and deformities calledwitch's broom. Its chemical profile is also altered: naphthodianthrone,flavonoid,amentoflavone, and pseudohypericin levels are reduced;chlorogenic acid levels are increased. Additionally, phytoplasma diseases greatly reduce the essential oil yield of the plant.[37]
Dieback among populations of St John's wort is also caused by fungalanthracnose, such asColletotrichum gloeosporioides. This fungus causes the stems to lose their bark (girdling) and turn brown, and dries the aboveground parts of the plant. The infection often kills the plant within the first year of its growth, or reduces productivity over a three-year deterioration.[38]
ThoughHypericum perforatum is generally avoided by mammalian herbivores, a number of insects are dependent on it and its close relatives as a food source.Chrysolina quadrigemina andC. hyperici are two beetle species that feed on plants from the genusHypericum, includingH. perforatum.Chrysolina quadrigemina can be colored metallic blue, purple, green, or bronze and is better adapted to warm and dry climates;Chrysolina hyperici is consistently smaller, metallic green, and tends to live in areas with wetter and cooler conditions.[39] AnotherHyericum specialist beetle isAgrilus hyperici, the St John's wort root borer, whoselarvae feed on the roots ofH. perforatum while the adults feed on the foliage.[40]
A moth,Aplocera plagiata, feeds heavily upon the leaves ofH. perforatum as a caterpillar and is commonly known as the common St John's wort inchworm. As adults, they are a small moth with gray wings and dark gray bands.[3] Another moth that feeds uponH. perforatum isEuspilapteryx auroguttella. Their caterpillars start by mining the inside of the leaves and later roll the leaves into cigar shapes to feed in greater safety.[41][42]Agonopterix hypericella is another small (17 mm (0.67 in)) gray moth that exclusively feeds uponHypericum.[43][42]
Zeuxidiplosis giardi, the common St. Johnswort gallmidge, is a small (3 mm (0.12 in)) fly that eatsH. perforatum while developing. The larvae feed upon leaf buds, which causes the plant to form a round growth called agall where the developing insect can feed, is protected, andpupates into a mature adult.[3]
Hypericum perforatum istoxic to numerous domestic animals such as cows, sheep, and horses. When these animals come into contact with the plant, usually through grazing, they develop serious symptoms. The first signs are reddening of the skin accompanied by swelling, which is followed bynecrosis andsloughing of the skin. Non-pigmented, white skin is most affected by the poisoning, such as the nose and ears of certain breeds of sheep.[44] Young animals are more susceptible toH. perforatum poisoning, and the plant is most toxic in spring (when it is the most palatable to herbivores) and retains its toxic effects when dried inhay.[45] Additionally, affected animals will become highlyphotosensitive, and exposure to sunlight can exacerbate their symptoms. As such, they should be moved to a dark area; administering ofantihistamines oranti-inflammatory medicines may also help alleviate the symptoms.[44]
Hypericum perforatum growing prolifically inBelair National Park, South Australia
AlthoughH. perforatum is grown commercially in some regions of southeast Europe, it is listed as anoxious weed in more than 20 countries and has introduced populations in South and North America, India, New Zealand, Australia, and South Africa.[34][36] In pastures, St John's wort acts as both a toxic and invasive weed. It replacesnativeplant communities andforage vegetation to the extent of making productive land nonviable or becoming an invasive species in naturalhabitats andecosystems.[46]
Effective herbicides for control ofHypericum perforatum include2,4-D,picloram,metsulfuron, andglyphosate.[3] Insect herbivores have also been introduced asbiocontrol agents in areas outside their native range. Some of the most widely used areChrysolina quadrigemina,Chrysolina hyperici,Agrilus hyperici,Aplocera plagiata, andZeuxidiplosis giardi.[3][47]
H. perforatum has approval in the European Union as a herbal product for the treatment of mild to moderate depressive episodes (according toICD-10) and for the short-term treatment of symptoms in mild depression.[48] It is more effective thanplacebo and as effective as standard antidepressants, includingSSRIs, for mild to moderate depression, with some evidence suggesting feweradverse effects and lower discontinuation rates.[49][50][51][52]
Common St. John's wort has been used inherbalism for centuries.[55] It was used inclassical antiquity and was a standard component of ancient concoctions calledtheriacs, from theMithridate ofAulus Cornelius Celsus'De Medicina (c. 30CE) to theVenice treacle ofd'Amsterdammer Apotheek in 1686.[56][57] One folk use included the oily extract known as St John's oil, a red, oily liquid extracted fromH. perforatum that may have been a treatment for wounds by theKnights Hospitaller, the Order of St John.[58] The dried flower is crushed to make the compound known asherba hyperici.[59]
H. perforatum generally produces a variety of yellows suitable fordyeing. When the pigments are extracted usingethanol, a violet-red colour is made which can be used to dye silk and wool when rinsed invinegar. The colours produced are season-dependent.[60]
The flowers produce a series of four different shades on wool, if used in the correct sequence. Woolmordanted withalum and unmordanted wool is used. The flowers are simmered to produce a deep red liquiddye. The alum-mordanted wool skein is added and simmered until green is made. If unmordanted wool is added to the same dye, it will turn reddish-maroon. The final colour produced is by continuing the method, to produce yellow or gold.[61]
There is no clinical evidence that St John's wort is effective to treatcancer.[62][63] TheNational Cancer Institute has commented that "the FDA has not approved the use of St. John's wort as a treatment for cancer or any other medical condition".[64] St John's wort may reduce the efficacy ofchemotherapy.[54]
Use ofH. perforatum may cause significantdrug interactions, primarily throughPXR activation andCYP3A4 induction linked to its hyperforin content, affecting the efficacy and safety of various medications.[53][65]
The increase in these enzymes have been found to be caused by high hyperforin content; consumption of St John's wort products with minimal hyperforin causes fewer side effects and less interference.[66] However, the concentration of St John's wort's constituent chemicals (including hyperforin) can vary widely between different products,[65] and their dosage may not be properly marked on packaging.[66]
Use ofH. perforatum may produceadverse effects when combined with other antidepressants through an increase in brain serotonin levels calledserotonin syndrome, which may be life-threatening and is associated with rapid heart rate, acutehypertension,mydriasis, andfever.[53][54]Photosensitivity and acuteneuropathy upon sun exposure, and reduced response tochemotherapy are other possible effects.[54][65]
Common side effects of St John's wort products are headache, nausea, fatigue, dry mouth, sleepiness, andgastrointestinal upset.[55][54] It should not be consumed during pregnancy and breastfeeding.[53][54]
^James L. Stubbendieck, Stephan L. Hatch, L. M. Landholt (2003).North American Wildland Plants: A Field Guide (illustrated ed.). University of Nebraska Press. p. 323.ISBN978-0-8032-9306-9.
^Chen SY, Hamer D (2003)."Common St.John's Wort".A Field Guide to Non-Native Species of Eastern Massachusetts. Brandeis University. Retrieved29 July 2023.
^abMerrit Lyndon Fernald (1970). R. C. Rollins (ed.).Gray's Manual of Botany (Eighth (Centennial) – Illustrated ed.). D. Van Nostrand Company. p. 1010.ISBN978-0-442-22250-5.
^Coombes AJ (2012).The A to Z of plant names : a quick reference guide to 4000 garden plants. Portland, Oregon: Timber Press, Inc. p. 172.ISBN978-1-60469-196-2.
^Marcone C, Bellardi M, Bertaccini A (2016). "Phytoplasma diseases of medicinal and aromatic plants".Journal of Plant Pathology.98 (3):379–404.doi:10.4454/JPP.V98I3.060.JSTOR44280481.
^Ng QX, Venkatanarayanan N, Ho CY (March 2017). "Clinical use ofHypericum perforatum (St John's wort) in depression: A meta-analysis".Journal of Affective Disorders.210:211–221.doi:10.1016/j.jad.2016.12.048.PMID28064110.
^Süntar IP, Akkol EK, Yılmazer D, et al. (2010). "Investigations on the in vivo wound healing potential ofHypericum perforatum L.".Journal of Ethnopharmacology.127 (2):468–77.doi:10.1016/j.jep.2009.10.011.PMID19833187.
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