Field Guide to Noxious and Other Selected Weeds of British Columbia
St. John's-Wort
(Hypericum perforatum)
perennial from underground runners, growing 0.3 to 1 metre in
height; transparent dots are visible over the surface of the
oblong leaves when held to light; bright yellow flowers with 5
petals; plants turn a rusty red colour at maturity
contains a toxin that causes grazing animals to become sensitive
to sunlight resulting in intense skin irritation
Showy yellow flowers produce many stamens
Transparent dots on leaves contain a photosensitizing pigment
