Phylum: Magnoliophyta - Class: Equisetopsida - Order: Malpighiales - Family: Hypericaceae
There are several species of St John's-wort in Britain and Ireland, but this is one of the less commonly seen of the group ans easily distinguished by its creeping or trailing growth form. It is a low, creeping plant and much smaller than most other Hypericum species. The flowers are typically 8 to 10mm across.
Trailing St. John's-wort is widespread but most common in the west of Britain and Ireland.
The genus name Hypericum comes from the Greek hyper, meaning above, and eikon, meaning picture; it reflects the fact that these plants were hung above pictures in the belief that this would sefve to ward off evil spirits. The specific epithet humifusum means prostrate or sprawling - a reference to the growth habit of this plant.
The common name St John's-wort also deserves some explanation. The various St John's-wort flowers are virtually guaranteed to be at their peak around Midsummer's Day (21st June) and they have a long and ancient history associated with various festivals and processions that have taken place (and still do in some European countries) at about this time of the year. The Feast of St. John the Baptist takes place around the same time - 24th June - and from this the plant was given the common name that is still used today and which superseded other names given to the plant in ancient times when it was used in Pagan rituals at mid-summer.
Throughout the UK, Europe and the Near East many St. John's-wort species grow both in the wild and as cultivated plants in gardens. One of the most beautiful of the European species that grows in the wild is Hypericum olympicum which has very large flowers measuring up to 5.5 cm in diameter.
Hypericum calycinum, more commonly known to us as Rose of Sharon, originates in the Near East, and has even larger flowers - around 7 cm in diameter - and this is the species most familiar to us from gardens and parks throughout the UK. It is an agressive shrub which has become widely naturalised in the countryside, and can often be seen on roadside banks and verges, and also along railway lines.
Trailing St John's-wort can be mistaken for Yellow Pimpernel; a distinguishing feature is the longer leaves of the St John's Wort and the narrower petals. Tormentil, which has leaves somewhat reminiscent of those of Trailing St John's-wort, can also grow in trailing form, especially when on otherwise barren and compacted gravelly soil, but this plant has flowers with only four petals whereas the St John's-wort plants have five-petalled flowers.
We found this specimen growing on dry soil in a sunny spot in the Teifi Valley in West Wales. The photograph was taken in early August.
We hope that you have found this information helpful. If so we are sure you would find our books Wonderful Wildflowers of Wales, vols 1 to 4, by Sue Parker and Pat O'Reilly very useful too. Buy copies here...