St. John's Wort
Hypericum perforatum
Family:
Cluciaceae/Hypericaceae, St. John's Wort family
Where to find this herb :
Dry sandy soil, slopes, along roadsides
Part(s) used:
Flowers
Special constituents:
Essential oil, hypericin, pseudohypericin, hyperforin
Correspondance:
19,30 (Beyerl, Culpeper); 30 (Cunningham)
Uses:
Antidepressant, anti-anxiety. Magical: protection, fire-magic
Sint-Janskruid 
Perikon The glowing petals and fiery stamens of St. John's Wort lifts the mood and brings happiness. The herb has become famous the last 10 years because of the all the research that has been done on its antidepressant effects. The effects are mainly due to the hypericin compounds, which inhibit the enzyme monoamine oxidase (MAO).
Normally an extract of St. John's Wort is taken, in the form of pills. But you can also make your own St. John's Wort oil. Let the flowers soak in base oil (such as olive oil) for a few weeks. It gets a nice golden to reddish colour. You can use this oil as massage oil or mix it in creams. A few people get an allergic skin reaction to St. John's Wort, but for most it is completely safe to use.
The name St. John's Wort refers to John the Baptist. It is said that the herb grew where his blood fell when he was beheaded. Another legend tells the herb grew where the blood of Christ fell when he hung on the cross.
The botanical name "Hypericum" means (according to Mrs. Grieve) "over an apparition" and refers to the belief that the plant was so strong that evil spirits would fly away as soon as they detected it. The herb has also been known by the name "fuga aemonum" (flight of the devil), again a reference to the powers of keeping evil at bay; in German, "Teufelsflucht", Dutch "jaag den duivel" etc.
For these purposes, St. John's Wort is most effective if harvested 23rd June at 12 o'clock midnight.