St. Johns wort is showing up more and more on coastal BC and is a nasty invasive plant that has some good medicinal qualities. It has long been used medicinally as an anti-inflammatory for strains, sprains, and contusions. It also has been used to treat muscular spasms, cramps, and tension that results in muscular spasms.
St. john’s wort has two-sided, rust-red stems with clusters of yellow flowers with five distinctly separate petals. Its oblong leaves have prominent veins and are covered with dots which are transparent when the leaves are held up to the light. Mature plants grow to 1 m in height and turn a rusty red.
It invades grazed and disturbed lands. In dense stands, it displaces native plant species and reduces livestock and wildlife forage. The plant also contains a toxin that can cause skin irritation and blistering in light-colored livestock when they are exposed to sunlight.
In British Columbia, it grows at low to mid-elevations in coastal, grassland, and open forested regions, and along roadsides and disturbed areas. It occurs in scattered pockets all over the coast. The root system spreads laterally and is capable of forming new buds that separate from the parent.
Seeds have a gelatinous coat that facilitates long-distance bird and animal dispersal.