SLENDER ST. JOHN'S-WORT

Hypericum pulchrum

St John's Wort Family [Hypericaceae]

month8jun month8june month8jul month8july month8aug

status
statusZnative
flower
flower8bicolour
flower
flower8yellow
flower
flower8red
inner
inner8orange
morph
morph8actino
petals
petalsZ5
stem
stem8round
toxicity
toxicityZlowish

22nd June 2009, Gait Barrows, Silverdale, Cumbria. Photo: © RWD
An elegant plant to 60cm tall. More open-plan that any other St. John's wort, and therefore quite distinctive. The stems have shoots branching in pairs at distant intervals whilst the main stem continues through the branching where a small pair of opposing leaves emerge.


22nd June 2009, Gait Barrows, Silverdale, Cumbria. Photo: © RWD
The flowers are rich yellow on the top-side of the petals, but orange to red on the under-side (the outside of as yet un-opened flower buds). Flowering shoots are asymmetric and have a much smaller pair leaves at the junction.


22nd June 2009, Gait Barrows, Silverdale, Lancs. Photo: © RWD
Both the sepals and the petals have black dots on their periphery, the petals also having red dots. The stamens are long and numerous, typically having about 30 which are well collimated without spreading out far. They have a distinctive orange pollen. The sepals, less than half as long as the petals, are rhombic, with a 90° chamfer at the apex


22nd June 2009, Gait Barrows, Silverdale, Lancs. Photo: © RWD
The flowers are a large 12-18mm across, with petals that may have rotational asymmetry similar to propellers. Small black dots inhabit the periphery.


22nd June 2009, Gait Barrows, Silverdale, Lancs. Photo: © RWD
The black dots may be on short dark stalks. Note red markings on underside of petals.


22nd June 2009, Gait Barrows, Silverdale, Lancs. Photo: © RWD
The black dots on the petals are fairly in-conspicuous.


22nd June 2009, Gait Barrows, Silverdale, Lancs. Photo: © RWD
Un-opened flower buds have a neat appearance like a rugby ball nestling on a golf-tee. Note tiny bracts/leaves just underneath the bud.


22nd June 2009, Gait Barrows, Silverdale, Lancs. Photo: © RWD
Buds on the main stem may be larger than those on a side-branch.


22nd June 2009, Gait Barrows, Silverdale, Lancs. Photo: © RWD
Leaves are mid-green and un-like most (all?) St. John's Worts, half clasping the stem.


22nd June 2009, Gait Barrows, Silverdale, Lancs. Photo: © RWD
Leaves often have in-rolled margins.


22nd June 2009, Gait Barrows, Silverdale, Lancs. Photo: © RWD
Many of the larger leaves are heart-shaped and half clasp the stem (amplexicaul)


Uniquely identifiable characteristics

Distinguishing Feature : With so many identifying features (see photo annotations) this St. John's Wort is easily differentiated from the rest.

The books say that this Slender St. John's Wort avoids lime, for it is a calcifuge, which is at variance with the photographs above, which was found growing in Gait Barrows, a limestone area containing clints and grykes (many of which have previously been bulldozed flat for use as ornamental stones in gardens and on the sea-front at Morecambe). However, it is possible that sufficient peat had gathered where this particular lone specimen had established itself to create an acidic micro-habitat.

The stems yield a brown-red dye when alum is used as the mordant. The flowers, on the other hand, yield a yellow dye when alum is used as the mordant and an orange-red dye when tin is used instead.

NAPTHODIANTHRONES


Hypericin, together with Hyperfolin, are major constituents of St. John's Wort plants, and both owe their names to the scientific name for St. John's Worts.

 Hypericin is a red-orange coloured naphodianthrone, an anthraquinone derivative, and acts as an antibiotic if consumed. It is also fluorescent. Being a chromophore the molecule can cause photo-sensitization, which has been observed in animals which happen to eat any St John's Wort. Once an animal has become photo-sensitized to Hypericum, the sensitization will remain for the rest of its life, when further exposure of the skin to the sun results in skin lesions which develop 1-2 weeks after exposure. Subsequent exposure of the skin to UV light from the sun will result in increasingly severe symptoms.

Hypericin preferentially accumulates in cancerous tissues and has found use as an indicator of cancerous cells. By way of its photo-activation properties, it may also find use as a means of treating cancerous tissue which would then be activated when the tissue is illuminated by a strong source of light. It also exhibits photo-activated activity against various virii. It has (a much reduced) activity against viruses when in the dark, which may be mediated by a differing mechanism.

The Hypericin and Pseudohypericin being the cause of the colour in St. John's Worts, is concentrated mostly in the parts of the plant which are orange-red, being the flowers. Other coloured compounds called flavonoids also contribute to the yellow colour. One, Hyperoside (aka Hyperin), which is concentrated mainly in the flowers, is the 3-O-galactoside of Quercetin. Hyperoside is also present in Selfheal (Prunella vulgaris), Sheep's Sorrel (Rumex acetosella) and Round-Leaved Sundew (Drosera rotundifolia).

A PRENYLATED PHLOROGLUCINOL DERIVATIVE

Hyperforin is also found in the fruits and oil-glands of St. John's wort plants and is thought to be part of the plants defence mechanism against herbivores. It is thought to be a neuro-transmitter re-uptake inhibitor, acting on serotonin, Dopamine, norepinephrine, GABA and glutamate. Hyperfolin is a prenylated Phloroglucinol derivative and believed to be the primary active constituent in St. John's Wort extracts responsible for its anti-depressant and anxiolytic properties. Hyperforin is also an antibiotic active against MRSA. It is a bicyclic molecule with one 2-methylpropanoyl, one 4-methylpent-3-enyl and three 3-methylbut-2-enyl groups attached to the central rings.

There are many other acylphloroglucinols in the Dryopteris genus of Ferns, such as are detailed in Male-Fern (Dryopteris felix-mas).


  Hypericum pulchrum  ⇐ Global Aspect ⇒ Hypericaceae  

Distribution
 family8St John's Wort family8Hypericaceae

 BSBI maps
genus8Hypericum
Hypericum
(St John's-worts)

SLENDER ST. JOHN'S-WORT

Hypericum pulchrum

St John's Wort Family [Hypericaceae]