Perforate St John's-wort - Hypericum perforatum

Description

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.

Similar Species

Other St.John's-worts. See ID Aids below.

Identification difficulty
ID checklist (your specimen should have all of these features)

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

Identification aids

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.

Hypericum guide

 

Recording advice

A photo of the plant in its habitat and confirmation that leaves have translucent glands

Habitat

Rough grassland, road verges and hedgebanks.

When to see it

May to September.

Life History

Perennial.

UK Status

Common throughout much of Britain, but rare in central and northern Scotland.

VC55 Status

Common in Leicestershire and Rutland. In the 1979 Flora survey of Leicestershire it was found in 305 of the 617 tetrads.

Leicestershire & Rutland Map

MAP KEY:

Yellow squares = NBN records (all known data)
Coloured circles = NatureSpot records: 2025+ | 2020-2024 | pre-2020

UK Map

Species profile

Common names
Perforate St. John's-Wort, Common St. John's Wort, Perforate St John's-wort
Species group:
flowering plant
Kingdom:
Plantae
Order:
Malpighiales
Family:
Hypericaceae
Records on NatureSpot:
195
First record:
21/06/2001 (Jane McPhail;John Kramer)
Last record:
29/09/2025 (Hunt, Graham)

Total records by month

% of records within its species group

10km squares with records

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Latest images

Latest records

Photo of the association

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. 

Photo of the association

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.

Photo of the association

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. 

Photo of the association

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.