Common Name: St. Johnswort, Common St. Johnswort, Klamath weed, Goatweed, Perforate St. Johnswort – Saint John refers to Saint John the Baptist. The predominant etymology is that the flower blooms on or about 24 June, the Feast Day of Saint John in Catholic hagiography. There are several other theories that are described in detail below. Wort is from wyrt, Old English for herb.
Scientific Name: Hypericum perforatum – The generic name is probably a combination of hypo meaning below and erice, the Latin word for heath to describe its rocky, shrubby preferred habitat. Alternative explanations have been suggested as discussed below. The leaves have small translucent dots that look like little holes – perforare is Latin for “to bore through.”
Potpourri: St. Johnswort is good and bad … but not ugly. Numerous anther bearing male stamens project from the base of the ovary like a shock of spiky blond hair in a unique display of floral beauty. It is good as one of the most renowned medicinal plants with a tradition of healing that dates to antiquity. It is bad in part for the same reason. Plants produce chemicals to protect themselves from herbaceous insects. The unintentional consumption of large quantities of that same chemical by plodding herbivores can be pernicious. St. Johnswort is also good as a garden cynosure and several cultivars are grown horticulturally for that purpose. But this is also bad, as they can escape into the wild where reproductive success can overwhelm the delicate balance of an ecosystem. Nature is gray as a balance between the opposites of black and white … what is good for some is relative to that which is bad for others.
The Feast Day of Saint John the Baptist was perhaps the third most important holy day (whence holiday) in the medieval Christian calendar with the birth of Jesus on 25 December second and his Easter Sunday resurrection first. It is celebrated on 24 June, which is six months prior to Christmas in accordance with Luke’s Gospel (1:36) wherein the angel Gabriel informed Mary on the night of her immaculate conception that “your kinswoman Elizabeth in her old age has also conceived a son; and this is the sixth month with her who was called barren.” Just as Christmas conveniently falls near the winter solstice to coincide with the folk festivals that preceded it, Saint John’s day is close to its summer solstice counterpart with Earth at the solar antipode. Both holidays took advantage of extant customs and social gatherings and repurposed them from pagan saturnalia to deistic ritual. Saint John’s festival was replete with local customs that varied according to the time and the tradition. Among the more ecumenical of midsummer celebrations was the gathering of flowers, St. Johnswort among them. It was in many cases it was hung over the door to ward off evil spirits giving rise to a dubious alternate explanation of the genus name Hypericum as Greek for above (hyper) the door (eikon). 
The naming of one flower among many for a day given to the celebration of John the Baptist seems unlikely. An alternative etiology is that St. Johnswort was one of the most notable medicinal herbs in the Levant in an age when violent, bloody rampage and rape were rife. The Crusades were the culmination of the spread of Christianity north from Rome and Constantinople to the various Germanic and Slavic tribes that succeeded Pax Romana. Led by the Franks, the crusaders set out with religious fervor stoked by Pope Urban II in 1095 to free Jerusalem from the perceived Moslem yoke, eventually establishing a presence in the eastern Mediterranean that lasted until the fall of Acre in 1291. The Knights Hospitaller or Knights of Hospital of St. John the Baptist were formed to succor the Christians in the Holy Land in 1120, becoming “one of the noblest charitable bodies in the Christian world.” They certainly used a common herb for the treatment of their charges, which, due to their success as healers and fame as protectors, became identified with them as St. Johnswort. After the fall of Acre, the Hospitallers eventually resettled to Malta where they became the Knights of Malta until they disbanded five centuries later in 1799.  The legacy of their symbolic healing was retained eponymously with the wort they used.
It is not then surprising that St. Johnswort was gathered to celebrate the midsummer holiday. This was not just because it happens to bloom at about that time in northern temperate climates but because it was always good to have a store on hand for medical exigency. John Gerard was one of the more notable herbalists of sixteenth century England as the superintendent of gardens of one of Queen Elizabeth I’s primary advisors. He is credited with establishing the first comprehensive survey of medicinal plants even though his work is mostly plagiarized from an earlier work by the Dutch botanist Rembert Dodoen.  Gerard’s prescription for St. Johnswort was to steep the leaves, flowers, and seeds in olive oil and strain them to produce an “oile of the colour of blood” that could then be used as a “most precious remedie for deep wounds … or any wound made with a venomed weapon … because I know that in the world there is not a better.”  The reputation of St. Johnswort was further enhanced by divine provenance with the invocation of the doctrine of signatures by the botanist William Coles. The “signatures” idea started in central Europe with the assertion that God had made “herbs for the use of men” with “particular signatures, whereby a man may read, even in legible characters, the use of them.” Therefore, since the leaves of St. Johnswort are perforated with holes “like the pores of a man’s skin,” it was a “sovereign remedy for any cut in the skin.” 
With the benefit of modern laboratory assay, it is now known that St. Johnswort is a chemical cornucopia. The flowers, buds, leaves, and roots collectively contain at least ten classes of biologically active compounds ranging from amino acids to xanthones including thirty separate constituents. While some of these are necessary for the operations necessary to be a plant like photosynthesis, some are the result of ecological factors with which the plant must have contended in the past up to and including the present. This adjunct group, known generally as secondary metabolites, consists of molecular combinations randomly produced in response to things like sucking insects and pervasive bacteria. The war of the worlds that determines survival sub rosa is what makes plants (and fungi) excellent sources for potential human medicinals, as we seek to repel the same invaders. When the epidermal shield is breached by accident or assault, the body is wide open for exploitation. The chemicals of St. Johnswort have proven to be effective in stemming the tide of infection. One recent study tested oil extracts of Hypericum perforatum in incision models finding that they “possess remarkable wound healing and anti-inflammatory activities supporting the folkloric assertion.” 
The use of St; Johnswort has long since been extended well past basic first aid for cuts and bruises to a panacea for anything that ails the body either physically, or, in a thoroughly modern twist, mentally. Brewed as one ot the many herbal tea concoctions either in whole or in part, it has been promoted as a treatment for bladder problems, intestinal worms, diarrhea, and dysentery, among others. While there have been no clinical trials to prove efficacy, it is not beyond reason that the complex chemistry of St. Johnswort could have some ameliorative affect at least for some … and then there is the placebo effect; it works because you think it will. The known biologically active compounds of St. Johnswort include choline, pectin, rutin, sitosterol, hyperforin, hypericin, and pseudohypericin. The latter two compounds are notable as having anti-retroviral properties that are a key attribute of AIDS medications.  However, it is in mental health applications, notably depression, that St. Johnswort has been subject to rigorous trial and assessment. The results are mixed.
Treatment for mental disorders is not an exact science. There are no objective guidelines based on independent physical parameters on which to base diagnosis and treatment … no blood samples and no lungs to listen to. The Diagnostic and Statistical Manual of Mental Disorders (DSM) has eighteen broad categories ranging from anxiety disorder to sexual dysfunction. Diagnosis relies on verbal feedback from a patient concerning subjective assessments of moods, aspirations, and other quality of life measures. Treatment is largely trial and error prescription with a mix of psychopharmaceutic drugs and dose rates until there is patient-reported improvement. Mixing St. Johnswort with other drugs is the main reason for controversy concerning its use. Many studies have been undertaken to determine that it works if taken as a singular medication for depression. For example, a metanalysis of 66 studies involving over fifteen thousand mental health patients found that “hypericum extracts were found to be significantly superior to placebo, with estimated odds ratios between 1.69 and 2.03.” Further, there were fewer adverse effects with St. Johnswort than with other tested drugs so that patients were able to stick to the medication program.  The National Institutes of Health (NIH) is the gold standard for the health efficacy of medications. While it does not rule out St. Johnswort as a treatment for depression, it is emphatically stated that “combining St. John’s wort and certain antidepressants can lead to a potentially life-threatening increase in your body’s levels of serotonin, a chemical produced by nerve cells.” 
St. Johnswort is not a single plant. It is a family formally named Hypericaceae that consists of eight genera and over four hundred species that extends geographically across both temperate and tropical regions. The characteristic features of its constituents are shrubby plants having clustered flowers with five separate petals and five separate sepals and numerous stamens that are mostly yellow to orange.  Common St. Johnswort earned its moniker by being the most expansive species in the family. It is more than common, however. According to the USDA, it is an official weed in seven states, listed with the caveat “Caution: This plant may become invasive.” While it only invades disturbed areas generally leaving established habitats intact, it forms dense colonies that will crowd out native species nearby.  H. perforatum is native to Europe and was either accidentally introduced to North America with packing materials or purposely transplanted as a medicinal herb or ornamental garden flower … it was first noted in Pennsylvania in 1793. One century later it had migrated to the western United States and by 1940 it had reached Canada. It has since become a serious invasive problem in Mexico, Argentina, Chile, South Africa, Reunion, Japan, Australia, New Zealand and Hawaii. 
Common St. Johnswort is a problem because it is an extraordinarily successful plant. Each individual shrub produces an average of 33,000 seeds in a single season and each seed remains viable for at least three years―about half are still potent after fifteen years. The many seeds are small and therefore light enough to be dispersed by wind for distances as far as thirty meters, germinating even in marginal soils in shady locations. Once established, seed growth is supplemented by vegetative growth as rhizomes extend outward from the parent plant to produce a copse that then predominates. The seeds are also sticky to adhere to the coats of any passing animals for further dissemination. Aside from invasive weediness, a second problem arises incident to consumption of Common St. Johnswort by grazing animals. One of the unintended consequences of its complex chemical cocktail is that it causes photosensitization. This self-descriptive term means that exposed areas become sensitive to the photons of the sun’s energy field, particularly those in the ultraviolet range. For animals including humans, light-colored areas absorb more energy and are damaged … something like severe sunburn. This can wreak havoc with white (but not black) sheep and any other animal with white patches like horses and cattle. 
The alternative name Klamath weed is a case in point. The Klamath River basin of California was an important livestock grazing area that had succumbed to a gradual infestation of Common St. Johnswort in the early twentieth century. Starting in 1922, Dr. Harry Smith of California’s Department of Food and Agriculture sought a biological control agent, identifying several beetles that might be compatible. However, local resistance to introduced phytophagous species in a dense agricultural area stymied trials―a common issue due to fears of potential damage to cash crop staples. However, by 1944 over two million acres of rangeland had been essentially rendered useless by the “Klamath weed” and land prices plummeted as ranchers were unable to raise cattle due to the debilitating effects of photosensitization. Three candidate beetles were approved for introduction from Australia where they had already been successfully deployed from their native Europe to control St. Johnswort. In spite of the acclimatization issues due to seasonal reversal, one of the three (Chrysolina quadrigemina) survived and thrived. Five thousand were released in 1946 to establish a population of three million by 1950 which were then distributed throughout the western states. After ten years, St. Johnswort had been reduced by over ninety percent as land values rose by a factor of four saving over three million dollars a year. 
St. Johnswort is one of the most notable examples of ethnobotany―the complex interplay between plants and people. Within the constraints of its indigenous fons et origio, it evolved chemicals to deter herbivores from its destruction and an industrial scale reproductive capacity to advance its quest for survival and dominance. Resourceful hunter gatherers learned of its potency through random trial and error, making it a key ingredient of the herbal healer’s medicine chest. It spread with the advances of civilization whose pioneers brought it with them wherever they went to treat the wounds incurred as rite of passage. Unchecked by local predators in these new places, St. Johnswort proliferated unabated. Reestablishing nature’s balance to control its epidemic proliferation mandated the importation of its native beetle predators to its new habitat. After centuries of relocation and decades of remediation, St. Johnswort is once again living in harmony with its environment. The only difference is that what once was used for physical wounds has been repurposed to treat the depressed mental wounds that seem quid pro quo to the frenetic pace of human endeavor. One can only wonder what John the Baptist might have thought of this.
- https://www.cabi.org/isc/datasheet/28268 The Commonwealth Agricultural Bureau International is the primary agency for tracking invasive species and its impact on the food supply. This is a comprehensive fact sheet that also includes history, lore, and usage.
- Durant, W. The Story of Civilization, Volume 4, The Age of Faith, Simon and Schuster, New York, 1950 pp. 585-613.
- Gerard, John, Generall Historie of Plantes, John Norton Publisher, London, England, 1597, pp. 123-124.
- Coles William, The Art of Simpling, Angell in Cornhill, England, 1656 p. 87 reprinted by Provoker Press, St. Catherines, Ontario, Canada, 1968
- Greeson, J. et al. “St. John’s wort (Hypericum perforatum): a review of the current pharmacological, toxicological, and clinical literature”. Psychopharmacology 5 January 2001 Volume 153 (4): pp. 402–414.
- Süntar, I. et al “Investigations on the in vivo wound healing potential of Hypericum perforatum L”. Journal of Ethnopharmacology 3 February 2010 Volume 127: pp. 468–77
- Foster, S. and Duke, J. Medicinal Plants and Herbs, Houghton Mifflin Company, Boston, 2000, pp.128-129.
- Linde K. et al (February 2015). “Efficacy and acceptability of pharmacological treatments for depressive disorders in primary care: systematic review and network meta-analysis”. Annals of Family Medicine. 13 January 2015 Volume 13 (1): pp. 69–79. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4291268/
- “St. John’s Wort”. National Center for Complementary and Integrative Health, US National Institutes of Health. September 2016. https://www.nccih.nih.gov/health/st-johns-wort
- Niering, W. and Olmstead, N. National Audubon Field Guide to North American Wildflowers, Alfred A. Knopf, New York, 1998, pp. 557-561.
- https://faculty.ucr.edu/~legneref/biotact/ch-66.htm (University of California, Riverside).