Information on Perforate St John's-wort

Common Name: Perforate St John's-wort
Scientific Name: Hypericum perforatum
Irish Name: Lus na Maighdine Muire
Family Group: Hypericaceae
Distribution: View Map (Courtesy of the BSBI)
Flowering Period


Click for list of all flowering by month
Perforate St John's-wort could sometimes be confused with:

St John's-wort, Slender, St John's-wort, Trailing,

One of a large family of perennials, Perforate St John's-wort is distinguished from its cousins by two slightly raised lines running along the length of the cylindrical stems.  The five petals of its rich yellow flowers (25mm across) have tiny black dots or streaks on their margins and sometimes the pointed sepals are also edged with these dots. The centres of the flowers are like little pin-cushions with numerous stamens.  From May to September, these flowers are borne in terminal panicles, the plant reaching 75cm tall.  Holding the oval, opposite leaves to the light reveals tiny little translucent dots and there are also black gland dots on the leaves.  This wildflower is found in grassy places, open woodland and roaod verges, is a native plant and it belongs to the Hypericaceae family.  

I first identified this wildflower in Co Clare in 1977 and I photographed it in Co Kildare in 2009.  

If you are satisfied you have correctly identified this plant, please submit your sighting to the National Biodiversity Data Centre

St John's-wort, Perforate
St John's-wort, Perforate

St John's-wort is widely used in medicine as a treatment for depression and as an ointment for skin problems such as eczema.  It was available in Ireland as an over-the-counter anti-depressant up to the year 2000 when the Minister of Health at that time, Brian Cowen, made it a prescription-only medicine.