Perforate St John's-wort
Perforate St John's-wort - Hypericum perforatum
Short to tall, hairless, erect plant. Stems round with 2 raised lines, spreading and rooting at the base. Leaves opposite, linear to oval, unstalked, with large translucent dots. Flowers yellow, 18 to 22 mm in broad panicles, the petals with numerous black dots, mostly around the edges. Sepals narrow, with or without black glands, much shorter than the petals.
Other St.John's-worts. See ID Aids below.
Stem with 2 ridges; leaves with translucent glands (hold the leaf up to the light); sepals equal; some black glands on petals, sepals and leaves
The St John's Wort (Hypericum) family are attractive, yellow-flowered perennials. They can look confusingly similar but can be distinguished by careful examination of key features. A hand-lens may be required (depending how good your eyesight is!). The leaf perforations are visible as translucent dots if the leaf is held up to the light.
A photo of the plant in its habitat and confirmation that leaves have translucent glands
Rough grassland, road verges and hedgebanks.
May to September.
Perennial.
Common throughout much of Britain, but rare in central and northern Scotland.
Common in Leicestershire and Rutland. In the 1979 Flora survey of Leicestershire it was found in 305 of the 617 tetrads.
David Nicholls
Bloody Oaks
02 July 2015
David Nicholls
Bloody Oaks
02 July 2015
David Nicholls
Nature Alive, Coalville
12 July 2012
Graham Calow
Sapcote
24 June 2013
Perforate leaf
Graham Calow
Dunton Bassett Quarry
16 July 2015
Graham Calow
Sapcote
21 June 2014
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Additional images
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All NatureSpot records
Fomoria septembrella
The larva of the moth Fomoria septembrella mines the leaves of Hypericum species, most commonly Perforate St John's-wort at first in a narrow gallery, later becoming a blotch mine.
Euspilapteryx auroguttella
The larva of the moth Euspilapteryx auroguttella mines the leaves of various Hypericum species such as St John's-worts initially in a lower surface gallery and then into a blotch, becoming a small narrow tentiform mine lined with silk. Later on the larva feeds and pupates in a leaf margin folded down.
Dasineura hyperici
The larvae of the midge Dasineura hyperici cause galls on various Hypericum species (e.g. St John’s-worts). The topmost leaves form a loose ball; the basal part of the leaves is swollen and discoloured, but the upper part is not affected as much. There may be several larvae to a single gall, they are whitish at first, becoming orange or red later.
Dasineura serotina
The larva of the midge Dasineura serotina produces galls on Hypericum species such as St John's-worts. The gall is formed out of the terminal bud of a stem. The hyaline white larva is surprisingly small in relation to its gall.