The WALA Plant Library
St. John's Wort

Synonyms for St. John's Wort: Klamath Weed, Amber, Cammock, Penny John, Goatweed, Tipton Weed, The Devil's Scourge, The Grace of God, The Lord God's Wonder Plant, Witch's Herb, Hundred-Holes, Terrestrial Sun
Scientific Name: Hypericum perforatum L.
Family: Hypericaceae (St. John's wort family)


You can recognise St. John's wort immediately by the dots: if you hold the flowers up to the light you will see numerous small bright spots: glands containing a fluid of essential oils and resin. If you rub the golden yellow flowers between your fingers they will be stained blood red, the characteristic colour of St. John's wort oil. This wondrous colour change results from the fact that light and oxygen break down constituents of the flowers. The perennial St. John's wort plant grows to a height of 90 cm. From May/June to August/September the many branched, woody stems are covered over and over with the five-rayed flowers. This oil-rich plant, whose leaves are also densely covered with oil glands, grows by the wayside, on banks, on grassland, in open woods and scrub, preferably in the full sunlight which it requires for luxuriant growth.