| Hypericum× inodorum | |
|---|---|
 | |
| Hypericum ×inodorum 'Golden Beacon' in Belgium | |
Scientific classification | |
| Kingdom: | Plantae |
| Clade: | Tracheophytes |
| Clade: | Angiosperms |
| Clade: | Eudicots |
| Clade: | Rosids |
| Order: | Malpighiales |
| Family: | Hypericaceae |
| Genus: | Hypericum |
| Section: | Hypericumsect. Androsaemum |
| Species: | H. × inodorum |
| Binomial name | |
| Hypericum× inodorum | |
| Synonyms[1] | |
| |
Hypericum ×inodorum, calledtall tutsan or thetall St John's wort, is a bushyperennialshrub with yellow flowers native to Western Europe. It has been known since 1789, but confusion around its name, identity, and origin persisted throughout the 19th and 20th centuries.
Thenothospecies is a fertilehybrid ofHypericum androsaemum andHypericum hircinum, and a member of the familyHypericaceae. It possesses clusters of many golden yellow flowers with longstamens and red fruit that gradually changes color. It is frequentlycultivated forgarden display, with numerouscultivars sold for their various unique characteristics. A noted variety is 'Golden Beacon', which won theRoyal Horticultural Society'sAward of Garden Merit for its gold foliage, prominent stamens, pink stems, and superior disease resistance.
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.[2] The hybrid's author,Philip Miller, chose the nameinodorum (which comes from the Latin wordinodorus meaning odorless or "unscented")[3] to distinguish it fromH. hircinum, which commonly has a goat-like smell.[4] However, the name can be misleading, as some plants of the hybrid still have a strong scent.[4] The hybrid has historically been called tall tutsan or the tall St John's wort in English.[5][6]
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The first mention of this hybrid in botanical literature was inJoseph Tournefort's 1700 workInstitutiones rei herbariae. However,authorship of the species is given to Philip Miller, who included it in the 1768 edition ofThe Gardeners Dictionary. Both authors gave the following Latin polynomial to the plant, and Miller supplied an English translation:[7][8]
Furthermore, Miller designated aholotype for the plant: a cultivated specimen taken from theChelsea Physic Garden inLondon.[8][10]
In 1789,William Aiton described the same plant inHortus Kewensis under a different name:Hypericum elatum. He offered a longer description, with details on the flowers of the plant, and called it the "tall St John's wort".[6] The nameH. elatum was popularly used for the species throughout the 19th century, and it was included in a partialmonograph ofHypericum in 1821.[11]
Beyond these two names, the plant was misidentified in various ways by more than half a dozen botanists in the 19th and 20th centuries. It was described as both of its parents,H. androsaemum andH. grandifolium. Some English specimens were calledHypericum anglicum on several occasions, and the namesH. multiflorum andH. persistens have also been used. At some points, the plant was included in the genusAndrosaemum (now the section inHypericum to which it belongs) asA. pyramidale,A. parviflorum, andA. ×urberuagae.[1]
Norman Robson included the species in his assay of the genusHypericum inFlora Europaea in 1968, confirming that it was an intermediate form ofH. androsaemum andH. grandifolium and hypothesizing that it was a hybrid between the two species.[12] This was confirmed in the 1985 installment of Robson's monograph of the genus, along with a detailed description of the species and a history of itsnomenclature.[1]
Hypericum ×inodorum is a bushyperennialshrub that grows 0.6–2.0 meters (2 ft 0 in – 6 ft 7 in) tall and has a spread of 0.9–1.5 m (2 ft 11 in – 4 ft 11 in).[3][1] Its branches stand upright and many originate at the base, which does not root aboveground.[1]
The species' stems are cylindrical when the plant is mature. There is 0.2–0.8 centimeters of stem between pairs of leaves. The bark of the plant is scaly in texture. The leaves are directly attached to the stems, and do not have a leafstalk. Sometimes, the leaves even surround the stem somewhat. The leaf blades are 3.5–11 cm (1.4–4.3 in) long by 2.0–6.0 cm (0.8–2.4 in) wide, and are between an oval-lance shape and a wide egg shape, with a rounded or almost pointed tip. There are four or five pairs of main veins that arise from themidrib and ascend outwards in the direction of the tip of the leaf. The web of small tertiary veins is visible from either side of the leaf. There are small glands on the leaf, which are dense along its edges.[1]
Every cluster of flowers usually has 3–23 flowers, which arise from one or two distinct nodes. There are no lower accessory flowers, and thebracts are small and lance-shaped. Each flower is 1.5–3.0 cm (0.6–1.2 in) wide, and before blooming have globe-shapedbuds. Thesepal leaves overlap each other and vary in size. They measure 0.5–1.0 cm long and 0.2–0.5 cm wide, and remain on the flower until the fruit ripens, or longer. The petals are golden yellow, without any red tinge. They can either spread out or curve inwards, and they measure 0.8–1.5 cm long. Every bundle ofstamens has 20–30 stamens, the longest of which are 1.0–2.0 cm long. Theseed capsule has thin walls and is flesh, and goes from a red to dark brown color, sometimes splitting at its end. The seeds inside are red-brown and are 0.12–0.15 cm long. They have a wing on one side, and sometimes have wing-like appendages on their end.[11]
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Hypericum ×inodorum is native to France, Italy, and Spain. It has been introduced to the United Kingdom, Ireland, Chile, Java, Madeira, Mexico, New Zealand, Portugal, and Switzerland.[13] The origin ofHypericum ×inodorum has been misunderstood in several ways. William Aiton claimed it came from North America in 1789,[6] and it took until 1886 for its status as an Old World species to be determined. In the 20th century, several botanists misidentified specimens of the hybrid forH. grandifolium, thus believing it originated inMacaronesia.[14] According to Robson, the plant's habitat is in lowlands "in damp or shaded places".[14]
Melampsora hypericorum is arust fungus known as tutsan rust. It parasitizes several related species ofHypericum, includingH. ×inodorum.[15] Thepestaloid fungusSeimatosporium hypericinum has also been found infesting the plant in Brazil.[16] In cultivated forms of the hybrid,insect herbivory anddiseases are not major threats to the plant.[17]
Hypericum ×inodorum is widely cultivated as anornamental plant. It is hardy and capable of tolerating a variety of sun and soil conditions, including apH range of at least 6.0–8.0. It is resistant to both drought and heavy shade.[3]
In many publications, the 'Elstead' variety is the most prominently or onlycultivar mentioned.[18][19] The cultivar has small flowers that are 2.5–3.0 cm (1.0–1.2 in) wide with styles 0.6 cm long. The berries are 1.6–1.7 cm long by 0.8 cm wide and go from white to a bright pinkish-red as the plant matures.[4][17] Because plants flower over about two months, many different stages of berry color can be seen at the same time.[17]
Another notable cultivar is the 'Wilhyp' or 'Golden Beacon' variety.Hypericum ×inodorum 'Golden Beacon' is a plant with gold foliage, prominent stamens, pink stems, and superior disease resistance.[20] It has received theRoyal Horticultural Society'sAward of Garden Merit because of these attributes.[21] Other less prominent cultivars include 'Summergold' (which has golden leaves),[4] 'Red Star' (with red-tinted stems and foliage),[22] 'Magical White' (with white berries),[23] and 'Magical Universe' (resistant to rust fungus).[24]
| Image | Name | Origin | Characteristics |
|---|---|---|---|
 | 'Elstead' | Royal Botanic Gardens, Kew[4] | White berries that become bright red[18][17] and small star-shaped flowers.[19] |
| 'Wilhyp' ('Golden Beacon') | Wales[20] | Gold-colored foliage, pink stems, and disease resistance.[20][21] |
 | 'Kolmpass' ('Magical Passion') | ||
 | 'Kolmahwi' ('Magical White') | Red stems with prominent white berries.[23] |