Today, you mostly hear of St. John's wort (Hypericum perforatum, St. Johns wort family, Hypericaceae) as a medicinal plant. It has been shown to be effective treating depression, anxiety, and sleep disorders and is widely used for those. But when I studied ecology in graduate school in the 1970s, under its American name, Klamath weed, it was the weed in a major weed-control story. So here are both tales.
|St. John's wort, Klamath weed, Hypericum perforatum|
|St. John's wort as a weed in a field, |
So it is both a major protective herb and a terrible weed.
St. John's wort is a woody shrub that can grow three feet high. The flowers are bright yellow and distinctive for the spray of anthers above the five petals. The leaves are oval, arranged opposite each other, and dotted with what look like tiny holes if you hold the leaf up to the light. That is what "perforatum" refers to in the scientific name, and is a good character for telling common St. John's wort, Hypericum perforatum, from other species of Hypericum, many of which have been introduced to the United States as ornamentals because of the handsome flowers. The holes are actually tiny clear glands that contain the active chemical of St. John's wort, hypericin.
The name Hypericum, given to this plant by Linnaeus when setting up the scientific name system, is Greek for hyper meaning above and eikon meaning picture, referring to the practice of hanging the flowers above images or windows. I have seen that also translated as "over an apparition" with much the same meaning. Alternately, Hypericum could mean "over heath" hyper plus ereike "heath" indicating it grows "over the heath (uncultivated land)." I don't know Greek and cannot judge these alternatives, except to say everyone is repeating the first one these days. The authorities I read hedged on the identification of the Greek plant--maybe it wasn't our Hypericum perforatum--but agreed that Hypericum perforatum had many of the same traditional uses in Europe as the ancient Greek Hypericum. My source for plant families, the Angiosperm Phylogeny website, puts St. John's wort in its own family, Hypericaceae, but previously it was in the larger Clusiaceae.
One last piece of St. John's wort folklore: on the Isle of Wight you were warned that if you stepped on the plant after dark, a phantom horse would emerge from the plant's roots, rising with you on its back, and gallop away, running the whole night long and, ultimately, leaving you far from home to make your own way back.
|St. John's wort flowers|
Comments and corrections welcome.
Hypericum perforatum. Missouri Plant Finder link Accessed 8/30/2020.
Legner, E.F. 1966. Klamath weed. link
Klamath weed. 2012. The Nature Niche blog link Accessed 8/29/2020.
Vickery, R. 1997. Oxford Dictionary of Plant-Lore. Oxford University Press, Oxford.