Hypericum androsaemum: Difference between revisions

Hypericum androsaemum
	Hypericum androsaemum, Tutsan
Scientific classification
Kingdom:	Plantae
Clade:	Tracheophytes
Clade:	Angiosperms
Clade:	Eudicots
Clade:	Rosids
Order:	Malpighiales
Family:	Hypericaceae
Genus:	Hypericum
Section:	Hypericum sect. Androsaemum
Species:	H. androsaemum
Binomial name
	Hypericum androsaemum; L.

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Hypericum androsaemum, the shrubby St. John's Wort, is a flowering plant in the family Hypericaceae. Commonly called tutsan or sweet-amber, the species is cultivated as an ornamental plant because of its striking red-tinted foliage, bright yellow leaves, and its clusters of fruit which are large compared to other members of Hypericum. As such, various cultivars of the species have been bred which amplify its desirable characteristics. These include cultivars like 'Albury Purple' and 'Golden Tutsan' which have more pronounced purple and golden leaves, respectively. The plant is widely and densely distributed across Western Europe, as well as more sparsely in North Africa and the Middle East. Found in damp areas of high rainfall, H. androsaemum has also been invasively introduced to numerous countries, including in Australia and New Zealand where it is considered a noxious weed.

The species has been known since before the modern system of taxonomy was developed, but was first described by Carolus Linnaeus in 1763. Since then, it has been invalidly published as more than a dozen different synonyms, and was repeatedly placed in its own genus named Androsaemum. After Norman Robson published his monograph of the genus Hypericum in 1996, the species was definitively placed within Hypericum sect. Androsaemum, a small section including several other closely related species.

Description

Hypericum androsaemum is a small bushy shrub, reaching 30–70 cm (0.98–2.30 ft) tall. It has many stems growing from a branching base without visible roots; these stems remain upright and erect instead of creeping over the ground. It has many oval-shaped leaves along its stems which are typically green with a red tint, and have small glands on their surface that can be seen upon close inspection and are filled with a red pigment. The plant is many-flowered, with tiny yellow flowers of five petals each and numerous stamens. It has unique berries among Hypericum that turn from red to black and remain soft and fleshy even after ripening.^[1]

Foliage

The plant's stems are cylindrical in shape when the plant is mature.^[1] When viewed in cross-section, two small wing-like protrusions can be seen on opposite sides. Like other Hypericum species, the structure of the stem in juvenile plants consists of, from the outer layer to the center: an epidermis with a thin cuticle, three or four layers of chlorophyll tissue, a reserve tissue layer with round cells, and then an endodermis with thick double-convex structures on its radial walls. As the plant matures, the cells of the epidermis become smaller, and their cell walls that are tangent to the outside become thicker through suberin enrichment.^[2] If there is bark on the stems, it has longitudinal grooves or scale-like patterns.^[1]

The leaves are directly connected to the stems and they lack petioles, sometimes even wrapping around the stem somewhat. They are separated by internodes that are 3–9 mm (0.12–0.35 in) long. The leaf blade is typically 4–12 cm (1.6–4.7 in) long, but can be as short as 2.5 cm (0.98 in) or as long as 15 cm (5.9 in) in rare cases; the blade is 2–8 cm (0.79–3.15 in) wide.^[1] At the middle, the leaves measure around 126 µm thick.^[2] They have either a shape between that of an oval and an egg, or a more broad and triangular egg shape. The end of the blade is rounded or rarely blunted, while the base ends in an abruptly horizontal shape. The leaves are paler on the underside, are papery in texture, and do not have a glaucous wax coating.^[1] The leaves are smooth and without trichomes on either surface. The upper surface lacks any areolae or stomata that break up its regular cell profile, which consists of convex rectangular cells with undulating cell walls on all sides. The lower side does have some stomata which are surrounded by smaller cells and are slightly sunken in.^[2]

There are four or five symmetrical pairs of main veins along the leaf that point in the direction of the tip. The tertiary veins are prominent on both sides.^[1] There are only a few veins on the uppermost surface, with an undulating or linear pattern. There are many small vein cells and they are also convex.^[2]

There are small oil glands across the leaf that are more densely distributed on the margins of the leaf.^[1] When these glands are crushed, they give off a pungent aroma and leak red pigment. This pigment is more pronounced in the fall.^[3] There are also other translucent glands that are dispersed throughout the mesophyll at differing depths.^[2]

Inflorescence

Different angles of the small inflorescence

Hypericum androsaemum can have anywhere between one and eleven flowers on an inflorescence, from one or two distinct nodes. The inflorescence has a corymb-like arrangement with the branches more or less continuing to ascend in line with the stem. There are never accessory flowers, but there are sometimes one to three flowering branches from the lower node. The pedicel stems that bear the flowers are 8–14 mm long, with small bracts that are lance-like and tapering to a point.^[1]

The flowers are small, just 15–25 mm in diameter, and have buds that are a round globe shape. The sepals measure 6–12 mm long by 3–7 mm wide. They are imbricate, overlapping one on top of the other. They are visibly all different sizes, and become enlarged after the flower fully opens; they remain once the plant fruits but become deflexed. The shape of the sepals is an oval or egg shape, but can be a wider egg shape as well; they have rounded tips. They have seven to nine secondary veins that clearly divide the sepal. There are glands on the main blade of the sepals that take the form of individual dots or lines of dots; these glands are rather denser on the edges of the sepal blade. The flower petals are a bright golden yellow without the red tinge that is present in the foliage. They curve inward and have an egg-like shape with the narrower end towards the center of the flower. They are around the same length or slightly shorter than the sepals, 6–10 mm long and 3–7 mm wide. The stamens are arranged in fascicles of twenty to twenty-five stamens, though they can rarely have up to thirty stamens, the longest of which are 7–11 mm long. The ovaries measure 4–5 mm long and 3.5–5 mm wide; their shape is between that of an ellipse and a rough globe, and their ends are rounded or blunt. The styles are 2–2.5 mm long, roughly half the length of the ovaries. They stand upright, with their upper half curving sharply outwards.^[1]

The berries of the plant turn from red to a unique black color not found in any other Hypericum species, and are caused by a special xanthone present only in Hypericum androsaemum. Another unique characteristic of the species' berries is that they remain fleshy and mostly soft when they ripen, instead of hardening and drying out like other related species.^[4] The berries measure 7–12 mm long and 6–8 mm wide. They have thin walls or casings and are lucent (appearing to glow). They do not split to release their seeds when ripe, but can sometimes split in three if pressure is applied when they do dry out. The seeds inside are a reddish-brown color. They are winged unilaterally but do not have and wing-like appendages on the ends.^[1]

Phytochemistry

Hypericum androsaemum has a well-studied phytochemical profile as a result of its widespread use as folk medicine and an herbal supplement. In particular, the essential oil composition of its leaves have been analyzed in depth. More than eighty distinct compounds have been identified in various densities, which fluctuate throughout the calendar year. The overall density of essential oil has been recorded as high as 0.34%, from specimens collected in February. Several different sesquiterpene hydrocarbons dominate the profile year-round, while intermediate and long chain alkenes are highly present in late winter and early spring. Less prolific but still notable compounds harvested include caryophyllene and gurjunene.^[5] Many of these essential oils and other phenolic compounds are present in higher quantities during the floral development life stage while the flowers are still budding and growing.^[6]

While less thoroughly studied than the leaves of the plant, the berries of H. androsaemum are rich in chemical constituents as well. Many of these constituents are found in higher densities (or only) in the red-colored phase of the fruits. The highest levels of chemicals are chlorogenic acid, shikimic acid, rutin, epicatechin, and hyperoside.^[4]

Taxonomy

Hypericum androsaemum is the type species of the small section Hypericum sect. Androsaemum. The species' placement within Hypericum can be summarized as follows:^[7]

Hypericum

Hypericum subg. Hypericum

Hypericum sect. Androsaemum

H. androsaeumum

Nomenclature

The genus name Hypericum derives from the Greek words hyper, meaning above, and eikon, meaning picture. This refers to the practice of hanging the flower "above pictures" to ward off evil spirits. The specific epithet androsaemum comes from the Greek word androsaemus, which was used to describe plants with red sap. It is a combination of the words andros, meaning man, and haima, meaning blood.^[8] The common name tutsan is French in origin, and derives from the phrase tout-saine, which means heal-all, in reference to the plant's medicinal properties.^[3] Its alternative name sweet-amber is in reference to the ambergris-like aroma that is emitted when oil glands on its leaves are crushed.^[9] The species also has various local names, such as kamaçina in Turkey.^[6]

While Hypericum androsaemum is the most well-known plant named tutsan, other species share that common name. For example, H. xylosteifolium is called "Turkish tutsan" and H. hircinum is called "Stinking tutsan".^[6]

History

the species. However, since that original description numerous illegitimate synonyms have been created for various reasons. In fact, while there is now solid consensus that H. androsaemum belongs within the genus Hypericum,^[10] it was placed into a separate genus called Androsaemum as recently as 1893.^[11]

In 1796, the garden of Chapel Allerton published a list of their plant specimens, noting Hypericum androsaemum as being in their collection, along with the fact it had been described by Linnaeus. However, they still applied two superfluous names (Androsaemum floridum and Hypericum floridum) to their specimens;^[12] these names were never accepted as legitimate.^[10] Only one validly published heterotypic synonym for Hypericum androsaemum has arisen since its original description. In 1785, Carlo Allioni published a description of a specimen he called Androsaemum officinale, without referencing Linnaeus' original description of Hypericum androsaemum. Still, the description corroborated with the one given by Linnaeus and there is consensus that the specimen Allioni observed did, in fact, belong to Hypericum androsaemum and was not a separate species.^[13]

The status of Hypericum androsaemum was definitively resolved with Norman Robson's comprehensive monograph of the genus Hypericum in 1996. Robson established 36 sections within the genus which grouped together very similar species. He designated H. androsaemum as the type species of sect. Androsaemum, and also clarified its lectotype specimen. Because the actual type specimen that Linnaeus analyzed was not preserved, Robson selected an illustration from Hortus Cliffortianus, which Linnaeus would have at least seen, to serve as the lectotype for the species.^[1]

Synonyms^[10]
Name	Type	Author	Year	Journal			Notes
Name	Type	Author	Year	Title	Vol.	Page	Notes
Androsaemum androsaemum	Homotypic	(L.) Huth	1893	Helios	11	133	Not validly published
Androsaemum floridum	Homotypic	Salisb.	1796	Prodr. Stirp. Chap. Allerton		369	Superfluous name
Androsaemum officinale	Heterotypic	All.	1785	Fl. Pedem.	2	147
Androsaemum vulgare	Homotypic	Gaertn.	1788	Fruct. Sem. Pl.	1	282
Hypericum bacciferum	Homotypic	Lam.	1779	Fl. Franç.	3	151	Superfluous name
Hypericum bacciforme	Homotypic	Bubani	1901	Fl. Pyren.	3	343	Superfluous name
Hypericum floridum	Homotypic	Salisb.	1796	Prodr. Stirp. Chap. Allerto		369
Hypericum webbianum	Heterotypic	G.Nicholson	1894	Hand-List Trees Shrubs	1	37	Not validly published

Subdivision

Hypericum androsaemum exhibits a great deal of variation in appearance, especially in cultivation. When this variation is deliberately brought out through selective breeding, the resulting forms are called "cultivars"; however, when populations develop unique traits on their own while in cultivation, those populations can be described by a legitimate botanical name. In the case of H. androsaemum, two such names have been given: H. androsaemum var. aureum has yellow-green leaves, and H. androsaemum f. variegatum has variegated leaves.^[1]

In the wild, there is also a range of physical traits exhibited by H. androsaemum. Larger-flowered plants will more often have red-tinted leaves and larger fruits; smaller-flowered plants have more green leaves and smaller fruits. These traits are not binary, though, and there is a continuous spectrum of forms that link those two extremes wherever they are found. Thus, no legitimate names are given to any of these forms.^[1]

Similar species

Hypericum androsaemum is similar in appearance to the other species in section Androsaemum. It can be told apart from H. foliosum and H. × inodorum by its shorter styles, the unique black color of its ripe berries, and that its petals are never longer than its sepals.^[1] In addition to the species of section Androsaemum, it is highly similar to Hypericum xylosteifolium, the sole species in section Inodorum. The most apparent morphological difference between it and H. xylosteifolium is that the seed capsules (berries) of the latter species dry completely when they are mature, whereas those of H. androsaemum remain soft and fleshy.^[6] The berries of H. androsaemum only dry if they are left on the plant for around a month after ripening, and will begin to wither at that same time.^[1]

Comparison of inflorescences of related species
H. foliosum
H. × inodorum
H. androsaemum

Habitat

Hypericum androsaemum is found in damp and shady areas at a great range of elevations, from low-lying regions up to 1,800 m (5,900 ft).^[1] It requires heavy rainfall, typically greater than 750 mm (30 in) of annual precipitation.^[3]

Distribution

The species has a wide distribution, but is most densely found in Western Europe. It is particularly abundant across Great Britain (except for in the Scottish Highlands), in the Ardennes forest of Belgium and France, and the western French coast. Other European populations include the Pyrenees Mountains, across northern Spain and Portugal, and around Genoa and parts of central Italy. Scattered sightings have been reported through Germany and as far north as Denmark, as well as in Switzerland, Austria, and the Balkans. Outside of Europe, H. androsaemum is found in northern Turkey, the North African coast, the Caucasus, and Iran. While it may have at one point been present on the island of Corsica, it is now believed to be extinct there.^[1]

Hypericum androsaemum has also become naturalized or invasive in other regions. In Australia, it is densely found in the Otway Ranges, South Gippsland Hills, Dandenong Ranges, the Blue Mountains, and in the area around Mansfield. There are also a few scattered populations on Tasmania, but it is not troublesome there. In New Zealand, it is found on both islands frequently enough to be an encroaching weed.^[3]

Invasiveness

In the late 19th century, H. androsaemum was a popular ornamental plant, leading to its widespread dispersal in non-native regions. While its seeds don't have any special properties that increase their potential for dispersal, they are small and extremely numerous. This allows the seeds to easily contaminate cargo, animals, clothing, vehicles, or other transported items. The species was invasively introduced to Australia in 1865 via the Royal Horticultural Society's botanical garden in Hobart, apparently for use as an ornamental species because of its reddish leaves and bright yellow flowers. In New Zealand, the primary method of invasive dispersal is reportedly by birds.^[3]

In 2008, Landcare Research began investigating the feasibility of a biological control for the species. The seed and leaf-tip eating moth Lathronympha strigana and the leaf-feeding beetle Chrysolina abchasica were tested and found to be sufficiently host specific and not a risk to native plant species. As of February 2017, moths were released at 30 sites around the central North Island in New Zealand; however, the beetle is more difficult to rear in captivity, so only one release has been made so far.^[14]

Ecology

Seeds of Hypericum androsaemum germinate in the fall. They flower when the plant is between 18–24 months old, typically from late spring to early summer, with the fruit ripening by late summer. The plant is partially deciduous, losing most of its foliage in the fall but with rapid regrowth every spring.^[3]

Cultivation

When cultivated, Hypericum androsaemum requires minimal maintenance. The species is generally pest and disease free, and is deer resistant.^[15] However, it can be prone to nematodes which cause root rot; pest insects such as thrips and scale have also been noted. Additionally, in hot and humid climates the species is susceptible to wilting and unrelated root rot.^[9] It is tolerant of moderately acidic and alkaline soils, and can withstand drought and freezing temperatures down to -20° C (-4° F). While the plant performs best if spaced roughly 90 cm (3.0 ft) apart from others, it will self-sow via seed in its area if allowed, creating ground cover. After the plant has lost its leaves in the fall, it can be cut back if needed and will regrow from the base in the spring.^[16]

Most Hypericum species are difficult to germinate because of heavy seed dormancy. Hypericum androsaemum exhibits both physiological dormancy and chemical dormancy, meaning that seed germination can be kickstarted by both physical and chemical factors. In particular, room-temperature water or the plant hormone gibberellic acid were most effective at bringing its seeds out of a dormant state.^[17]

To propagate new specimens, non-dormant seeds should be sown in a 10° C (50° F) greenhouse in the spring under a very light layer of soil. Once the seedlings are large enough to handle (after 1–3 months), they should be moved into individual pots. After the last frost of winter, the new plants can be moved to their permanent outdoor locations. As an alternative method to seed propagation, cuttings of semi-hard wood 10–12 long can be taken in the fall. The cuttings should be placed in a frame for the remainder of the fall and winter, and then can be replanted the following spring.^[16]

Cultivars

In order to combat the invasive tendencies of Hypericum androsaemum, triploid clones of plants with desirable characteristics have been developed by several herbariums.^[18] These triploid specimens have been shown to have massively reduced male fertility and complete female infertility; in addition, they still produce the large and colorful fruits for which H. androsaemum is known, and at rates similar to regular diploid plants.^[19]

Selected cultivars
Name	Creator	Characteristics	Notes
'Albury Purple'		Leaves flushed purple, fruit more red	Also called 'Tedbury Purple'^[20]
'Glacier'		Leaves with primarily white variegation	^[21]
'Golden Tutsan'		Leaves golden	^[22]
'Matisse'	North Carolina State University	Leaves with green and white spotty variegation	Triploid^[18]
'Picasso'	North Carolina State University	Leaves with purple tint	Triploid^[23]
'Pollock'	North Carolina State University	Leaves with abstract color patterns	Triploid^[24]

Uses

Like many other Hypericum species, H. androsaemum has been and still is used as a folk medicine in various parts of the world. For example, it is used as a diuretic, to treat sciatica and gout, and to stem bleeding and accelerate healing from burns and minor wounds.^[3] Because H. androsaemum does not contain hypericin, a chemical present in other Hypericum species that can cause skin irritation and other undesirable side effects, the plant is more widely used in topical applications and skincare.^[25] In Portugal, the leaves are also used to treat liver, kidney, and bladder ailments,^[26] while in England they are mixed with lard to make an ointment to put on cuts or other wounds.^[27] The antioxidant properties of the berries of Hypericum androsaemum have been confirmed in laboratory testing, lending credence to their use in teas as antihepatotoxics or diuretics.^[4]

References

^ ^a ^b ^c ^d ^e ^f ^g ^h ⁱ ^j ^k ^l ^m ⁿ ^o ^p ^q Robson, Norman (1985). Studies in the genus Hypericum L. (Guttiferae): 3. Sections: 1. Campylosporus to: 6a. Umbraculoides. Bulletin of the British Museum (Natural History). ISBN 0565080032.
^ ^a ^b ^c ^d ^e Perrone, Rosaria; Rosa, Paolode; Castro, Olgade; Colombo, Paolo (2013-10-01). "Leaf and stem anatomy in eight Hypericum species (Clusiaceae)". Acta Botanica Croatica. 72 (2): 269–286. doi:10.2478/botcro-2013-0008. ISSN 0365-0588.
^ ^a ^b ^c ^d ^e ^f ^g Parsons, W. T. (2001). Noxious weeds of Australia. E. G. Cuthbertson (2nd ed.). Collingwood, VIC, Australia: CSIRO Pub. pp. 384–385. ISBN 0-643-06514-8. OCLC 46774815.
^ ^a ^b ^c Caprioli, Giovanni; Alunno, Alessia; Beghelli, Daniela; Bianco, Armandodoriano; Bramucci, Massimo; Frezza, Claudio; Iannarelli, Romilde; Papa, Fabrizio; Quassinti, Luana; Sagratini, Gianni; Tirillini, Bruno; Venditti, Alessandro; Vittori, Sauro; Maggi, Filippo (2016). "Polar Constituents and Biological Activity of the Berry-Like Fruits from Hypericum androsaemum L." Frontiers in Plant Science. 7. doi:10.3389/fpls.2016.00232/full. ISSN 1664-462X.{{cite journal}}: CS1 maint: unflagged free DOI (link)
^ Guedes, Ana P.; Amorim, Lúcia R.; Vicente, Ana; Fernandes-Ferreira, M. (2004). "Variation of the essential oil content and composition in leaves from cultivated plants ofHypericum androsaemum L." Phytochemical Analysis. 15 (3): 146–151. doi:10.1002/pca.758. ISSN 0958-0344.
^ ^a ^b ^c ^d Cirak, Cuneyt; Seyis, Fatih; Özcan, Aysel; Yurteri, Emine (2022-06-01). "Ontogenetic changes in phenolic contents and volatile composition of Hypericum androsaemum and Hypericum xylosteifolium". Biochemical Systematics and Ecology. 102: 104429. doi:10.1016/j.bse.2022.104429. ISSN 0305-1978.
^ "sect. Androsaemum [(Duhamel) Godron ]". hypericum.myspecies.info. Retrieved 2023-04-21.
^ "Hypericum androsaemum | Landscape Plants | Oregon State University". landscapeplants.oregonstate.edu. Retrieved 2023-04-07.
^ ^a ^b "Hypericum androsaemum - Plant Finder". www.missouribotanicalgarden.org. Retrieved 2023-04-16.
^ ^a ^b ^c "Hypericum androsaemum L. | Plants of the World Online | Kew Science". Plants of the World Online. Retrieved 2023-04-21.
^ Moldenke, Harold N. (1932). "A Discussion of Tautonyms". Bulletin of the Torrey Botanical Club. 59 (3): 142. doi:10.2307/2480467. ISSN 0040-9618.
^ Salisbury, R. A. (1796). Prodromus stirpium in horto ad Chapel Allerton vigentium. Londini: [s.n.]
^ Zumaglini, Antonio Mauritio (1849). Flora Pedemontana : sive Species plantarum Phanerogamarum in Pedemonte et Liguria sponte nascentium ... Vol. 1. Augustae Taurinorum [Torino]: J. Favale.
^ Hugh Gourlay. "Tutsan Agents Released". landcareresearch.co.nz.
^ "Hypericum androsaemum (Sweet Amber)". Gardenia.net. Retrieved 2023-04-07.
^ ^a ^b , "Hypericum androsaemum Tutsan, Sweet-amber, St. Johnswort PFAF Plant Database". pfaf.org. Retrieved 2023-04-07.
^ Çýrak, Cüneyt (2006). "Physiological and Physical Seed Dormancy of some Hypericum Species Growing in Turkey". Plant Breeding and Seed Science. 53.
^ ^a ^b "Hypericum androsaemum 'Pollock' (Expressionistic™ Tutsans, St. John's Wort, Sweet Amber, Tutsans) | North Carolina Extension Gardener Plant Toolbox". plants.ces.ncsu.edu. Retrieved 2023-04-07.
^ Trueblood, Clara E.; Ranney, Thomas G.; Lynch, Nathan P.; Neal, Joseph C.; Olsen, Richard T. (2010-07-01). "Evaluating Fertility of Triploid Clones of Hypericum androsaemum L. for Use as Non-invasive Landscape Plants". HortScience. 45 (7): 1026–1028. doi:10.21273/HORTSCI.45.7.1026. ISSN 0018-5345.
^ "Hypericum androsaemum 'Albury Purple' - Plant Finder". www.missouribotanicalgarden.org. Retrieved 2023-04-18.
^ "PlantFiles: Hypericum, Sweet Amber, Tutsan, St. John's Wort, St. Johnswort". Dave's Garden. Retrieved 2023-04-18.
^ "Hypericum androsaemum 'Golden Tutsan' - Plant Finder". www.missouribotanicalgarden.org. Retrieved 2023-04-18.
^ "Hypericum androsaemum 'Matisse' (Expressionistic™ Tutsans, St. John's Wort, Sweet Amber, Tutsans) | North Carolina Extension Gardener Plant Toolbox". plants.ces.ncsu.edu. Retrieved 2023-04-16.
^ "Hypericum androsaemum 'Picasso' (Expressionistic™ Tutsans, St. John's Wort, Sweet Amber, Tutsans) | North Carolina Extension Gardener Plant Toolbox". plants.ces.ncsu.edu. Retrieved 2023-04-16.
^ Antognoni, Fabiana; Lianza, Mariacaterina; Poli, Ferruccio; Buccioni, Michela; Santinelli, Claudia; Caprioli, Giovanni; Iannarelli, Romilde; Lupidi, Giulio; Damiani, Elisabetta; Beghelli, Daniela; Alunno, Alessia; Maggi, Filippo (2017). "Polar extracts from the berry-like fruits of Hypericum androsaemum L. as a promising ingredient in skin care formulations". Journal of Ethnopharmacology. 195: 255–265. doi:10.1016/j.jep.2016.11.029. ISSN 0378-8741.
^ Valentão, Patrícia; Fernandes, Eduarda; Carvalho, Félix; Andrade, Paula Branquinho; Seabra, Rosa Maria; Bastos, Maria de Lourdes (2002). "Antioxidant Activity of Hypericum androsaemum Infusion: Scavenging Activity against Superoxide Radical, Hydroxyl Radical and Hypochlorous Acid". Biological and Pharmaceutical Bulletin. 25 (10): 1320–1323. doi:10.1248/bpb.25.1320. ISSN 0918-6158.
^ Aronson, Jeff (2005-04-01). "David E Allen and Gabrielle Hatfield, Medicinal plants in folk tradition: an ethnobotany of Britain and Ireland". Medical History. 49 (2): 230–231. doi:10.1017/s002572730000870x. ISSN 0025-7273.

[:0-1] ^ ^a ^b ^c ^d ^e ^f ^g ^h ⁱ ^j ^k ^l ^m ⁿ ^o ^p ^q Robson, Norman (1985). Studies in the genus Hypericum L. (Guttiferae): 3. Sections: 1. Campylosporus to: 6a. Umbraculoides. Bulletin of the British Museum (Natural History). ISBN 0565080032.

[:8-2] Perrone, Rosaria; Rosa, Paolode; Castro, Olgade; Colombo, Paolo (2013-10-01). "Leaf and stem anatomy in eight Hypericum species (Clusiaceae)". Acta Botanica Croatica. 72 (2): 269–286. doi:10.2478/botcro-2013-0008. ISSN 0365-0588.

[:1-3] ^ ^a ^b ^c ^d ^e ^f ^g Parsons, W. T. (2001). Noxious weeds of Australia. E. G. Cuthbertson (2nd ed.). Collingwood, VIC, Australia: CSIRO Pub. pp. 384–385. ISBN 0-643-06514-8. OCLC 46774815.

[:6-4] Caprioli, Giovanni; Alunno, Alessia; Beghelli, Daniela; Bianco, Armandodoriano; Bramucci, Massimo; Frezza, Claudio; Iannarelli, Romilde; Papa, Fabrizio; Quassinti, Luana; Sagratini, Gianni; Tirillini, Bruno; Venditti, Alessandro; Vittori, Sauro; Maggi, Filippo (2016). "Polar Constituents and Biological Activity of the Berry-Like Fruits from Hypericum androsaemum L." Frontiers in Plant Science. 7. doi:10.3389/fpls.2016.00232/full. ISSN 1664-462X.{{cite journal}}: CS1 maint: unflagged free DOI (link)

[5] Guedes, Ana P.; Amorim, Lúcia R.; Vicente, Ana; Fernandes-Ferreira, M. (2004). "Variation of the essential oil content and composition in leaves from cultivated plants ofHypericum androsaemum L." Phytochemical Analysis. 15 (3): 146–151. doi:10.1002/pca.758. ISSN 0958-0344.

[:7-6] Cirak, Cuneyt; Seyis, Fatih; Özcan, Aysel; Yurteri, Emine (2022-06-01). "Ontogenetic changes in phenolic contents and volatile composition of Hypericum androsaemum and Hypericum xylosteifolium". Biochemical Systematics and Ecology. 102: 104429. doi:10.1016/j.bse.2022.104429. ISSN 0305-1978.

[7] "sect. Androsaemum [(Duhamel) Godron ]". hypericum.myspecies.info. Retrieved 2023-04-21.

[8] "Hypericum androsaemum | Landscape Plants | Oregon State University". landscapeplants.oregonstate.edu. Retrieved 2023-04-07.

[:2-9] "Hypericum androsaemum - Plant Finder". www.missouribotanicalgarden.org. Retrieved 2023-04-16.

[:4-10] "Hypericum androsaemum L. | Plants of the World Online | Kew Science". Plants of the World Online. Retrieved 2023-04-21.

[11] Moldenke, Harold N. (1932). "A Discussion of Tautonyms". Bulletin of the Torrey Botanical Club. 59 (3): 142. doi:10.2307/2480467. ISSN 0040-9618.

[12] Salisbury, R. A. (1796). Prodromus stirpium in horto ad Chapel Allerton vigentium. Londini: [s.n.]

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