Herbariuma Backpackers project
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St John's wort

Hypericum perforatum

Family · Hypericaceae · Irritating

Traditional use
St John's wort (Hypericum perforatum)St John's wort (Hypericum perforatum)
Didier Descouens, CC BY-SA 4.0 · JackyM59, CC BY-SA 4.0

The yellow summer flower with a trick: hold a leaf up to the light and you see hundreds of transparent dots, as if it were pierced. Hence the Portuguese name milfurada.

Where it grows

Roadsides and waste ground · Fields and pasture · Scrubland · Uplands

Also known as

perforate St John's wort

In flower

How to tell it

A leaf held to the light is full of translucent dots, which are oil glands. Yellow petals with black dots along the edge, and your fingers stain purple if you crush the flower.

What it is confused with

No dangerous lookalikes known in the Iberian Peninsula.

What it is for

A European folk medicine plant with centuries of use, and today the subject of clinical study. Two warnings that belong on the sheet: it photosensitises skin in animals and people, and it interacts with several medicines, including contraceptives. Not something to self-administer.

With documented traditional uses. Not a therapeutic indication and not a dose.

Sources