Index- plants in this Family
Clusiaceae / St. Johnswort
Common St. Johnswort (Hypericum perforatum)
Common St. Johnswort is also known as St. Johnswort, Perforate St. John's Wort and Klamathweed.

Plant Type: This is a non-native herbaceous plant, it is a perennial which can reach 75cm in height (30inches). The lower stem is often woody and has two small ridges.
Leaves: The leaf arrangement is opposite. Leaves can reach 5cm in length (2inches). Each leaf is entire and has translucent spots (glands) that can be seen when held up to the light.
Flowers: The flowers have 4 Regular Parts and are up to 2cm wide (0.75 inches). They are yellow. Blooms first appear in early summer and continue into early fall. The petals often have have black dots along one edge.
Fruit: A brown capsule.
Habitat: Fields, fencerows and waste places.
Range: Almost all of North America

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There are several Hypericums referred to as St. Johnswort, but, this is the only non-native one in our area. Most have dots (glands) on the leaves that are either translucent or black and sometimes large enough to be seen with the unaided eye. Identifying the various species can be tricky because they have many similarities and authors do not always agree in their descriptions. This species has been highly valued for centuries in Europe for it's medical and magical powers but is considered a weed in this country.

Lore: Considered a charm against witchcraft and evil sprits at least as far back as ancient Greece an entire volume could be devoted to the mystical uses of this plant. As was often the case, Christians picked up the traditional uses and, perhaps because it begins to bloom around St. John's Day, June 24, it became a symbol of the John the Baptist. Following pagan practices it was used by priest during the dark ages in performing exorcisms.(Dobelis) Used to protect against evil sprits and sickness (cause and effect during the middle ages) it was considered more potent if smoked in fires kindled on St. John's day.(Rickett) The glands on the leaves were thought to look like wounds and so, according to the doctrine of signatures the plant should be good for treating wounds. So it was that the Knights of St. John of Jerusalem used it to treat the wounds of Crusaders.(Volák & Stodola) In this case the doctrine proved correct.

Medical Uses: Hypericums contain large amounts of tannins, various glycosides such as hypericin and rutin and the essential oil catechol. Long used medically in the old world and the new it is a popular herbal remedy today. Thought it is not approved for medical use in this country compounds from the plant are regularly given as prescriptions in some European and Eurasia countries especially for depression. The plant is known to be a mild sedative, anti-inflammatory, astringent, antiseptic, diuretic. An oil extract made with olive or sunflower oil is used to treat wounds, burns, insect bites and many other external conditions. Native Americans used Hypericum for several conditions that tannin would be appropriate for and as a tea to treat tuberculosis. Testing shows it may be effective against tuberculosis. Warning:May cause irritation to sensitive skin and taken internally may make the skin more sensitive to light.

Similar Species: Spotted St. Johnswort, Hypericum punctatum

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More Info:  
The Search below may provide more information about this species. Some of URLs may have been used as a source for this page not otherwise cited. Most of the information not cited comes from multiple sources that can be found in the Books page. The USDA plant links are provided by: USDA, NRCS 1999. The PLANTS database ( National Plant Data Center, Baton Rouge, LA 70874-4490 USA. You can check species names at ITIS Advanced Search to see if they meet the current ITIS taxonomic criteria.

By: Newcomb, Lawrence and Illustrated by Morrison, Gordon. 1977, Little, Brown and Company, ISBN:0-316-60442-9

One of the best general guides to wildflowers of the North Eastern and North Central United States. Newcomb's key is an excellent, simple method for identifying plants. Newcomb has drawings for almost every plant mentioned that are excellent aids to identifying the species. Though only the more common plants are covered this is often the first book I pick up when trying to identify a wildflower.

Wildflo wers of Tennessee the Ohio Valley and the Southern Appalachians
By: Dennis Horn and Tavia Cathcart and Thomas E. Hemmerly and David Duhl. , ISBN:1551054280

This is perhaps the best of many field guides covering this region. Featuring 446 excellent color photographs (located with the text) and mentioning as similar to those illustrated are another 800 or so species for a total coverage of over 1,200 species. The start of each family section includes line drawings of some of the species showing important features. The text includes the usual description, bloom season, range, habitat and additionally includes information such as medical uses and lore and how the species was named. This is the official field guide of the Tennessee Native Plant Society.

Angiosperms / Flowering Plants
Dicots / Two Seed Leaves
St. Johnswort



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