St John’s wort ( Hypericum perforatum ) is a plant of/in the family Hypericaceae, which is native in Europe and Asia, but exists as introduced, sometimes invasive species in America, Australia, and in general, in all warm and temperate climate zones.
The glabrous stalk can grow up to 1m high, branches in upper parts, bearing yellow flowers in terminal corymb/bostryx ( type of cymose inflorescence ) . Leaves are opposite, oblong, without
bearing translucent dots, which are
actually oil- containing glands, and can easily be noted when the herb is
held against the light, hence the
species latin name “perforatum” ( lit. perforated ) .
|St John's wort botanical illustration|
Flowers are actinomorphic , with 5 petals ( corolla ) and 5 sepal ( calyx ), petals bearing black dots, mostly on the edges, which are , like those on leaves oil glands. They are around 2.5 cm in diameter.
Due to contents of hypericine, and hyperforine, it’s clynicaly proven to be efficient in treating mild to moderate depression, as well as some other neurological conditions such as anxiety, OCD and insomnia.  Infused oil of St John’s wort is a traditional European herbal medicine for first degree burns, cuts and smaller bruises, and is proven to have antibacterial effect. However, it also phototoxic , which means it causes skin photosensitivity in some people, though in much lesser degree than Angelica essential oil or Rue.
Use in herbal magick
“ To drive away “phantastical spirits,” according to Robert
Burton’s 17th-century work, The Anatomy of Melancholy, St.
John’s wort should be gathered on a Friday and then “hung
about the neck.” “
Gerina Dunwhich in : “Herbal magick – a witches guide to Herbal folklore, enchantments and divination”
St John’s wort is a traditional Midsummer plant , and is thus traditionally plucked / harvested on Midsummer / St John’s feast day which also happens to be the Holy day of Voodoo .
It’s associated with St. John the Baptist through various Christian legends. One of them speaks how upon the beheading of St John , the plant started excreting red oil. The Latin name for the genus “Hypericum” comes from old Greek “hyeprikon” which means “over apparition/icon” reffrencing the custom of hanging the dry plant wreaths and bundles over Saint’s Icons among the Orthodox Christians, who firmly believe that the plant has extremely strong apotropaic powers, that can repel even the Dev*l himself.
It’s no wonder then, that one of the names for it is also “Fuga daemonium” ( Latin, lit. chase away –demons ). Another common name for the plant, “Sol terrestis” ( Latin lit. Sun of Earth, or Earthly Sun , also Sun on Earth ) speaks of plant’s association with Solar power, and symbolically also the power of light to chase away darkness.
“When placed in a jar and hung by a window St. John’s wort protects against thunderbolts, fire, and evil spirits”  says the Cunningham’s encyclopedia of Magical herbs . St John’s wort is particularly powerful when picked on Midsummer and dried over Midsummer fires, it’s said to provide prophetic dreams about Your future spouse ( when placed bellow pillow ), and to repel ghosts, evil spirits, and hinders necromancers, and keeps them away from home. It’s often burned to repel ghosts and evil spirits in form of incense.
According to Cunningham, the herb was in ancient times used to detect witches, or rather force them to admit that they are of such, by holding it against their mouths. 
It’s also a power herb, that infuses practitioner with energy, both life energy ( “chi”, “prana” ) and the magickal one (“mana” ) hence it’s good for practitioner that feel drained or tired, or need extra “boost” for their work. It’s often mixed with Frankincense tears for this and burned as incense. To make a power oil, You can combine St John’s wort gathered on Midsummer, Frankincense tears and Heliotrope harvested during August. Mind though, that is an extremely powerful stuff that will amplify spells strength and all the good, but also the bad that may come as a result of it.
St John’s infused oil can be used in funerary rites and mysteries, as well as in exorcism. Herb hung over bed of several people in the same house, can be used to fortel which of them will die first. It’s the person who’s herb has wilted overnight , who was taught to be the first among the group to die.
In Balkan peninsula folklore, the herb is associated with Virgin Mary, but retains the same properties, as elsewhere in Europe. Additionally, it’s believed to be able to magickally cure infertility. For this purpose the herb must be gathered and not bought, oftentimes a child is sent to do it, and then blessed by Christian priest. Then it’s used to make an infusion ( tea ) which women drink to cure infertility, particularly when the Moon is full or waxing. The tea is drunk for a couple of consecutive days, and some of the herbs women should carry with her ( as a talisman ) at all times 
Recipes and formulas
Double John and evil’s gone oil
Just an idea that occurred to me when I was writing this. St John’s wort is not traditionally used in Hoodoo, but this formula, containing it, references Hoodoo symbolism and terminology and uses High John the Conqueror root.
· High John TC root and
· St John’s wort
In some base oil, like Olive oil, macerate until it gets quite red in color, and then it’s ready to use.
Use to conquer evil, to defeat long standing or persistent curses, or defeat and exorcize demons, and adverse conditions.
Some St John’s wort herb would make brilliant addition to “Run Dev*l run” Hoodoo oil, both as a dying agent and a powerful magickal adjunct to the formulae .
Power lifting incense
· St John’s wort gathered at Midsummer
· Frankincense tears
Burn during rituals or waft oneself with smoke for magickal empowerment, strength and endurance.
Herbal charm to hinder witches and render them unable to harm You
Combine Trefoil, Vervain, St. John’s wort and Dill, and carry in a mojo bag when You have to face, or fight evil witches.
According to an old English saying : “Trefoil, vervain, St John’s wort and dill, hinder witches of all their will” 
NOTES: This article was written/created by myself, therefore, If You wish to use any part of it elsewhere online feel free, but do add credits: Shadow of the Shadows magick place, Shadowfirstname.lastname@example.org , or a direct link to this post.
CREDITS AND REFRENCES:
 Acc. to the http://www.webmd.com/vitamins-supplements/ingredientmono-329-ST.%20JOHN'S%20WORT.aspx?activeIngredientId=329&activeIngredientName=ST.%20JOHN'S%20WORT
 “Cunningham's Encyclopedia of Magical Herbs” Llewellyn publications, pg. 224th and 225th
 As under 
 Veselin Cajkanovic “Recnik Srpskih narodnih verovanja o biljkama” pg.10th
 Rhyme retrieved from “Witchcraft and Black magick” by Montague Summers , page 179th, used here for educational and explanatory purposes
IMAGE CREDITS: St. John's wort illustration is from https://middlepath.com.au/plant/img/StJohnsWort_botanical-illustration.jpg used here for illustrative and explanatory, and educational purposes without any ill will, or intent of copyrights infringement