St. John's wort

Hypericum perforatum

Hypericaceae

Sunshine-yellow roadside herb for low mood — famous, effective in mild cases, and a notorious interactor.

Herbal supplement. Powerful enzyme inducer — treat like a drug.

Parts used: Flowering tops
Traditional notes: Mild low mood · Seasonal gloom · Nerve pain oil (topical) · Minor wounds (oil)
Grow · USDA 6b: Perennial, USDA 5–8. Invasive in parts of North America — check local status. Surface-sow in spring. Spreads by runners and seed. In work: May · Jun · Jul
Harvest: Tops as flowers open, around St. John's Day (late June) in the north.

Harvest the flowering tops on a bright day — the buds should stain purple.
It spreads by runners. A wild patch is a gift; a bed may need an edge.
Dry in the dark to keep the red oil color.

Safety

Any interacting prescription Bipolar disorder Bright-sun high-dose use without caution

Lore

Picked on St. John’s Day and hung against lightning and low mood. Crush a bud: it bleeds purple. The same plant can make you sunburnt and can make a prescription disappear in the liver.

The Herbarium — a teaching catalog, not a clinic. Traditional use is history, not a prescription. USDA 6b dates are a week either way, not a promise. Do not eat, drink, or harvest a plant you cannot name.