Hypericum perforatum
Common St. Johnswort, Klamathweed, St. John’s wort, Tipton’s weed, chase-devil, amber, goatweed, rosin rose, god’s wonder plant
Description: herbaceous perennial
Place of origin: Europe, western Asia, North Africa
Urban habitat: Commonly found neglected residential and commercial landscapes, vacant lots, rubble dumps, abandoned meadows, tolerant of roadway salt and compacted soil; its tiny seeds are easily distributed by sticking to fur and clothing; it forms dense colonies that can inhibit the growth of nearby plants.
Ecological function: Disturbance-adapted colonizer of bare ground; food for pollinating insects
History: Hypericum perforatum first arrived in North America shortly after European settlement in the 1600’s and was likely re-introduced several more times after that. It is currently considered invasive in many parts of the US as well as in 20 other countries around the world. The plant has a long history of medicinal use in Europe, appearing in Dioscorides’ 1st century herbal volume. Historically, it has been used to treat numerous ailments including fevers, ulcers, rheumatism, digestive disorders, bladder problems, diarrhea, pulmonary problems and nervous disorders. More recently, it is used as a sedative and to treat depression. Native American tribes also found many medicinal uses for the plant, one of which was to induce abortions. It’s common name St. Johnswort has several explanations relating to stories about John the Baptist. Infusing the plant in alcohol produces a red dye. The plant is particularly unpopular with farmers because it it poisonous to livestock.