Botany

Taxonomy and Description
St. John's wort is a member of the genus Hypericum, of which there are 400 species worldwide. There is some disagreement as to the plant's family, some placing Hypericum in the segregate family Hypericaceae, while others place it in the family Guttiferae. However, most researchers now think that the morphological and chemical differences of the two families are insufficient to justify separating them (1,2).

The plants are described as glabrous perennials, erect and usually woody at the base. The ovate to linear leaves are sessile, opposite, and well-supplied with translucent glandular dots. The regular flowers have five short, subequal, entire, imbricate, basally connate sepals, and five persistent-withering yellow petals. The ovary is superior, capsicular, and three-styled. Stamens are many, arranged in bundles of threes, and the flowers are profuse, arranged in branched cymes which bloom from June until September. In the absence of insect pollination, apomixis commonly occurs.

St. John's wort should not be confused with rose of sharon (H. calycinum), a common ornamental ground-cover in the United States. Rose of sharon flowers and leaves are much larger than those of St. John's wort (though interestingly, anti-biotic substances have been extracted from H. calycinum that are similar in activity to substances in H. perforatum (3).

Range and Habitat
St. John's wort is native to Europe, West Asia, North Africa, Madeira and the Azores, and is naturalized in many parts of the world, notably North America and Australia (4,5). The plant spreads rapidly by means of runners or from the prodigous seed production and can invade pastures, disturbed sites, dirt roads, the sides of roads and highways, and sparse woods.

In the western United States, St. John's wort is especially prevalent in northern California and southern Oregon, hence one of its common names, "Klamath Weed". Because of the known photosensitizing properties of the plant, which can be toxic to cows and sheep, it has been considered a pest in some places. Prior to 1949, it was estimated to inhabit 2.34 million acres of rangeland in northern California. For years an attempt was made to control the plant with herbicides6, but with little success.

The solution to the problem with St. John's wort in northern California finally proved to be with biological methods of control, not pesticides. In 1946, the leaf-beetles Chrysolina quadrigemina Rossi, and to a lesser extent C. hyperici Forst, were introduced from Australia, where it had been observed that they had a voracious appetite for Hypericum. Their appetite proved to be so voracious, in fact, that by 1957 northern California's stands of St. John's wort were reduced to only 1% of their original number (5).

Ironically, however, at the time of release of the Chrysolina beetles in California, it was not known that herbalists would one day keep Hypericum populations well under control.

Etymology of Nomenclature
The name Hypericum is ancient and may have several derivations. Yperikon was first mentioned by Euryphon, a Greek doctor from 288 BC (7). Pliny called the ground pine Hyperikon, though also chamaepitys and corion (8). One common explanation for the name Hypericum is that it may derive from ereike (heather) and hyper (above) (9). However, although one Greek species of Hypericum looked similar to heather (though it grew taller), it seems more likely that the name derives from eikon (a figure, possibly an unwanted apparition) and hyper (above), which relates to the ancient use of St. John's wort to exorcise evil spirits or influences (10), since the plant may have been placed over religious icons as a symbol of protection. Linnaeus, who described the genus, thought that Hypericum came from yper (upper) and eikon (an image) (vv11).

The common name, St. John's wort, is obviously a reference to St. John. Its earliest use may date back to the 6th century AD when, according to Gaelic tradition, the missionary St. Columba always carried a piece of St. John's wort because of his great regard for St. John (12). Some early Christian authors claimed that red spots, symbolic of the blood of St. John, appeared on leaves of Hypericum spp. on August 29, the anniversary of the saint's beheading, while others considered that the best day to pick the plant was on June 24, the day of St. John's feast (10). In the Christian tradition, St. John represents light, hence the flowers were taken as a reminder of the sun's bounty (13).

History of Use
Dioscorides, the foremost herbalist of the ancient Greeks, mentions four species of Hypericum- -Uperikon, Askuron and Androsaimon, and Koris--which he recommends for sciatica, "when drunk with 2 heim of hydromel (honey-water)." He also claims that it "expels many cholerick excrement, but it must be given continuously, until they be cured, and being smeared on it is good for ambusta (burns)." H. crispum and H. barbatum, he writes, have "a diuretical facility....and of moving ye menstrua. The seed being drunk for 40 days drives away tertians and quartans (fevers occurring every 3 or 4 days, possibly malaria)" (14).

Theophrastus recommends H. lanuginosum, a Greek species, for external application, while Pliny says it should be taken in wine against poisonous reptiles. H. coris, another Greek species, was mentioned by Hippocrates and Pliny (15). Although many older authors attest that the ancients knew of Hypericum as Fuga daemonum and used it to drive away demons, none make reference to any specific writers (16). Dioscorides, Pliny, and Theophrastus do not mention either this name or this use of the plant, but herbalists from the 16th and 17th centuries commonly mention the name.

In the early humoral system of medicine, Galen considered Hypericum to be hot and dry, while Paracelsus wrote of the plant in the early 1500's that it could be used as an amulet against enchantments and apparitions (17). St. John's wort was used in early pre-Christian religious practices in England, and it has many legends written about it (18). For instance, one belief was that bringing the flowers of St. John's wort into the house on a midsummer eve would protect one from the evil eye, banish witches, etc. Another belief was that that if one slept with a piece of the plant under one's pillow on St. John's Eve, "the Saint would appear in a dream, give his blessing, and prevent one from dying during the following year" (17). The favor St. John's wort enjoyed is well expressed in the following poem (19):

St. John's wort doth charm all the witches away.
If gathered at midnight on the saint's holy day.
And devils and witches have no power to harm
Those that do gather the plant for a charm:
Rub the lintels and post with that red juicy flower
No thunder nor tempest will then have the power
To hurt or to hinder your houses: and bind
Round your neck a charm of a similar kind.

Several noted English herbalists, reflecting the general beliefs of their time, wrote very favorably of the virtues of St. John's wort. For instance, Gerard (ca. 1600) tells of the ointment he made of the plant as being a "most precious remedy for deepe wounds", and adds that "there is not a better natural balsam....to cure any such wound" (20).

Culpeper (ca. 1650), who was fond of ascribing astrological signs to medicinal herbs, says that Hypericum "is under the celestial sign Leo, and the dominion of the Sun." He goes on to say that "it is a singular wound herb, healing inward hurts or bruises," and that as an ointment "it opens obstructions, dissolves swelling and closes up the lips of wounds." Also, he claims it is good for those who "are bitten or stung by any venomous creature, and for those that cannot make water"--which use modern science confirms--and adds that the plant helps with "sciatica, the falling sickness and the palsy" (21).

Other early uses of Hypericum include as an oil (made by macerating the flowering tops of the plant in oil and then placing them in the sun for two or three weeks), which was "esteemed as one of the most popular and curative applications in Europe for excoriations, wounds, and bruises" (22). This preparation was even used by the surgeons to clean foul wounds, and was official in the first London Pharmacopeia as Oleum Hyperici (23).

Other popular folk-uses for St. John's wort have included: as a decoction for gravel and ulcerations of the ureter (24); for ulcerations of the kidneys, febrifuge, vermifuge, jaundice, gout, and rheumatism (25); as an infusion (1 ounce of herb to 1 pint water) for chronic catarrhs of the lungs, bowels, or urinary passages; and as a warm lotion on injuries to the spinal cord, for lacerated or injured nerves, bed sores, and lock-jaw (26).

The native American Indians used several indigenous species of Hypericum as an abortifacient, antidiarrheal, dermatological aid, febrifuge, hemostat, snake bite remedy, and general strengthener. After St. John's wort was introduced by European settlers, they used it as well for similar conditions (27,28).

As for the young United States, St. John's wort was not well-known and was rarely mentioned by prominent writers on the subject of medicinal plants. One of the first references to the plant is from Griffith (1847), who says it can be used as an oil or ointment for ulcers, tumors, and as a diuretic (29). Even the Eclectics, medical doctors from the late 1800's and early 1900's who favored herbs in their practice, did not use St. John's wort much.

Nonetheless, King, in his Dispensatory (1876), mentions its use in urinary affections, diarrhea, worms, jaundice, menorrhagia, hysteria, nervous imbalances with depression, and its usual external applications, including the use of the saturated tincture as a substitute for arnica, in bruises (30). In the later Felter-Lloyd revision of King's Dispensatory, tincture of St. John's wort, in a dose of 10-30 drops mixed with 4 ounces of water, taken in teaspoonful doses every 1-2 hours, is prescribed for spinal irritation, shocks, concussions, puncture wounds, and hysteria (31).

Today, modern American herbalists still use St. John's wort for many of the same conditions for which it has been recommended throughout the ages (32,33).

Chemistry
The genus Hypericum has an exceedingly complex and diverse chemical makeup. H. perforatum has been most intensively studied, but there is data available on 66 other species (34). The compounds that have been identified from H. perforatum can be divided into several classes, which are summarized along with their pharmacological activity in Table 1.