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status
flower
morph
petals
stem
toxicity
22nd June 2009, Trowbarrow, Silverdale, Lancs | Photo: © RWD |
Grows up to a metre high in open woods and grassy places, preferring lime or clay. |
3rd July 2010, Arnside shoreline, Cumbria. | Photo: © RWD |
With a spike (more properly called a grappe) of 5-petalled yellow flowers it has some semblance to Goldenrod and to Yellow Loosestrife. |
22nd June 2009, Trowbarrow, Silverdale, Lancs | Photo: © RWD |
Flowering branches split in opposite pairs at the juncture of an opposing pair of leaves, the pairs alternately up the stem at right-angles to each other. |
22nd June 2009, Trowbarrow, Silverdale, Lancs | Photo: © RWD |
The stems are round and hairy (rather than the downy of Pale St John's Wort) |
22nd June 2009, Trowbarrow, Silverdale, Lancs | Photo: © RWD |
Only the sepals have black dots (on their periphery), there being none on the leaves (most sources mention black dots on the periphery of the petals, but your Author can find no photographs on the internet of Hairy SJW to back this assertion up). |
22nd June 2009, Trowbarrow, Silverdale, Lancs | Photo: © RWD |
Flowers have five pale-yellow petals. |
25th July 2008, Westover Plantation, IoW. | Photo: (CC by 2.0) Hilary Higgins |
The black glands have stubby black stalks. The flowers are pale-yellow. |
22nd June 2009, Trowbarrow, Silverdale, Lancs | Photo: © RWD |
Petals narrowish, broadening near the half-way point. The flowers are between 15 to 22mm across. |
22nd June 2009, Trowbarrow, Silverdale, Lancs | Photo: © RWD |
About 25 stamens bearing slightly darker yellow pollen. Sepals have black dots (glands) around the periphery, which are seen to be on short dark stalks. |
22nd June 2009, Trowbarrow, Silverdale, Lancs | Photo: © RWD |
Leaves are yellowish-green and elliptical but lack black dots, which are not even on the underside, but possess translucent dots best seen by transmitted light (central leaf). |
22nd June 2009, Trowbarrow, Silverdale, Lancs | Photo: © RWD |
Two or three curved veins visible from tops of leaves. Leaves always in pairs; the smaller ones are on new sprouting shoots. |
22nd June 2009, Trowbarrow, Silverdale, Lancs | Photo: © RWD |
The leaves have less conspicuous shorter hairs. |
22nd June 2009, Trowbarrow, Silverdale, Lancs | Photo: © RWD |
22nd June 2009, Trowbarrow, Silverdale, Lancs | Photo: © RWD |
Hairs on leaves much shorter than those on the main stem. |
22nd June 2009, Trowbarrow, Silverdale, Lancs | Photo: © RWD |
Stem hairs white. |
3rd July 2010, Arnside shoreline, Cumbria. | Photo: © RWD |
Black dots on edges of sepals are seen to be like punchballs on short stalks. |
3rd July 2010, Arnside shoreline, Cumbria. | Photo: © RWD |
Leaves yellowish-green. |
25th July 2008, Westover Plantation, IoW. | Photo: (CC by 2.0) Hilary Higgins |
A harvested specimen. |
25th July 2008, Westover Plantation, IoW. | Photo: (CC by 2.0) Hilary Higgins |
The stems have no ribs running their length. |
25th July 2008, Westover Plantation, IoW. | Photo: (CC by 2.0) Hilary Higgins |
25th July 2008, Westover Plantation, IoW. | Photo: (CC by 2.0) Hilary Higgins |
The hairy parts of the plant, and where it obtains its name Hairy St John's-wort from. |
9th June 2018, Waitby Greenriggs, Kirby Stephen, Yorks. | Photo: © RWD |
A plant yet to develop flowers. Although the stem is round not square, it seems the leaves are apt to align themselves alternately in quadrature up the stem. |
9th June 2018, Waitby Greenriggs, Kirby Stephen, Yorks. | Photo: © RWD |
Leaf hairs stubbier than stem hairs. |
9th June 2018, Waitby Greenriggs, Kirby Stephen, Yorks. | Photo: © RWD |
Branched leaflets in the axils of the stem leaves. |
9th June 2018, Waitby Greenriggs, Kirby Stephen, Yorks. | Photo: © RWD |
The tiny translucent dots to be seen in leaves held against the light - another identifying feature of Hairy St John's-wort (but some other St John's-worts also have these dots - they just help narrow down the species). |
9th June 2018, Waitby Greenriggs, Kirby Stephen, Yorks. | Photo: © RWD |
Deep grooved veins on the upper surface of the leaves. The leaf hairs are shorter than the stem hairs. |
Easily mistaken for : many other
Easily mis-identified as : Some similarities to : Yellow Loosestrife and Goldenrod, both of these have spikes of yellow five-petalled flowers. Slight resemblance to : Agrimony in that the flowers are yellow with five petals, but the flowers on Agrimony are held very close to the main stem. According to some books and to Clive Stace, Hairy St John's Wort has black dots on the extremities of the petals, but your Author can find no photographs on the web purporting to be both Hairy St John's Wort and sporting black dots on the petals... Perhaps they are extremely small? St John's Worts can cause photosensitivity in livestock which consume the plant, the toxins being cumulative and may go un-noticed at first, only appearing after the animal has consumed some for a few days. Light-skinned animals are more susceptible, and may develop dermatitis and blisters on non-pigmented parts of the skin such as mouth, nose and ears when exposed to the sun. 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. All St John's Wort plants contain Hypericin and Hyperforin as the main constituents, which together are thought to be responsible for its reported therapeutic effects which may be good for certain people (and bad for others). See Slender St John's Wort for details of these and other compounds present in the Genus. It grows in open woodland, damp grass, banks of rivers and is to be found throuout most of the British Isles. It is rare or absent in Wales and Northern Scotland. It is native. |
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hirsutum ![]() |
⇐ Global Aspect ⇒ |
Hypericaceae ![]() |
![]() Hypericum (St John's-worts) |
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