HAIRY ST. JOHN'S-WORT

Hypericum hirsutum

St John's Wort Family [Hypericaceae]

month8jul month8july month8aug month8sep month8sept

status
statusZnative
flower
flower8yellow
morph
morph8actino
petals
petalsZ5
stem
stem8round
toxicity
toxicityZlowish

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.


22nd June 2009, Trowbarrow, Silverdale, Lancs Photo: © RWD
Petals narrowish, broadening near the half-way point.


22nd June 2009, Trowbarrow, Silverdale, Lancs Photo: © RWD
About 25 stamens bearing slightly darker yellow pollen. Sepals have black dots 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 punchbowls on short stalks.


3rd July 2010, Arnside shoreline, Cumbria. Photo: © RWD
Leaves yellowish-green.


Easily mistaken for : many other St' John's Worts.

Easily mis-identified as : Pale St. John's Wort but that has downy rather than hairy stems, the leaves lack transparent dots and have black dots on the underside (only). Pale St. John's Wort lacks black dots on the petals, but has similar black dots on the sepals.

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.


  Hypericum hirsutum  ⇐ Global Aspect ⇒ Hypericaceae  

Distribution
 family8St John's Wort family8Hypericaceae

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

HAIRY ST. JOHN'S-WORT

Hypericum hirsutum

St John's Wort Family [Hypericaceae]