The Mission of the Yellowstone County Weed Department is to assist the public, private, and other government agencies to manage and control existing noxious weed infestations as well as to prevent new invasive species from infesting Yellowstone County.

St. JohnswortHypericum perforatum L.

Hypericum family - Clusiaceae

Toxic

Rosette

Stem

Leaf

Bloom

Infestation

Video Supplied By Ravalli County Weed District

Attribute	Description
Toxicity	Humans and livestock.
Growth Habit	Perennial, erect, numerous branches.
Leaves	Opposite, attached directly to stem, 1 inch long, oblong, covered with transparent dots.
Stem	Woody at the base, 1 to 3 ft. tall, rust colored, with 2 ridges.
Flower	Yellow, ¾ inch diameter, in flat-topped clusters, 5 petals with numerous stamens.
Roots	Branched and deep; some shallow capable of sending up shoots.
Seeds	Small, shiny black, with rough texture in a round, pointed, three-part seed pod.
Reproduction	Seeds & new shoots.
Biological Controls	None used in Yellowstone County at this time.
Herbicides	None used in Yellowstone County at this time.
Caution	Contains a toxic substance which causes white-haired animals to become allergic to strong sunlight.