Hypericum perforatum L.
St. John’s Wort, Common St. John’s Wort, Common St. Johnswort
Common St. John’s wort is a native of North America, Europe, Asia Minor, Russia, India, and China.
Identification: Plants are less than 3' (91 cm) in height, and multiply branched. Leaves are oval, opposite, sessile, up to ⅝" (1.8 cm) × ¼" (7 mm), with smooth edges. Flowers are deep yellow, star-shaped, with a central, brushlike spray of stamens. If you look closely, there is a rounded ovary about ⅛" (3.2 mm) in diameter, from which emerge three styles, arranged like the legs of an inverted tripod. They are difficult to see because they are almost the same color and shape as the stamens, but they are longer and thicker. Some species of St. John’s wort have only a single style, so this is an identifying characteristic. Petals have serrated edges and small black dots on the serrations. Flowers are up to ⅞" (2.5 cm) across.
Medical: St. John’s wort is widely used to treat depression, and a number of studies have been performed to assess the efficacy of these treatments. Studies have reported contradictory results, and this has become a contentious issue, in part because pharmaceutical companies stand to lose a very profitable business in other antidepressant drugs. Some studies have concluded that St. John’s wort is more effective than placebo and equally as effective as tricyclic antidepressants, and roughly as effective as serotonin reuptake inhibitors such as Prozac and Zoloft. Other studies suggest no benefits. It is likely that St. John’s wort at least helps with depression.
Below is a comparison of some species of St. John’s wort:
|You are here
|Plant||4-18" (10-45 cm) tall, sometimes up to 31" (79 cm), heavily branched, with a shrublike habit. Branches may be 4-angled or smooth, tapering, and sometimes winged.||Less than 3' (91 cm) in height.|
|Flowers||¼" (6.3 mm) in size, yellow or yellow-orange, with five petals and 5-15 stamens. Beneath the petals of each flower there are somtimes green bracts that are narrower but roughly the same length, one for each petal. Blooms from July to October.||Bright yellow, star-shaped, with five petals and many yellow stamens about the length of the petals. Petals have serrated edges and small black dots on the serrations. Flowers are up to ⅞" (2.5 cm) across.|
|Leaves||Roughly oval in shape, and attached directly to the stem (sessile). They are opposite, unlobed, ½-1½" (1.3-3.8 cm) long and ¼-¾" (6.3-19 mm) across.||Oval, about ⅜" (1.2 cm) long, with smooth edges, occurring in opposing pairs.|
|Fruit||¹/₁₆-⅛" (2-3.5 mm) in length.|
|Habitats||Sandy forest floodplains, sandy swamps, moist to wed sandy prairies; damp, sandy, acidic areas in general|
|Occurrence||Common, sometimes invasive|
Hypericum perforatum on Missouriplants.com
Hypericum perforatum on Wikipedia
Hypericum perforatum on www.mayoclinic.com
Hypericum perforatum on Plants for a Future, a resource and information centre for edible and otherwise useful plants
Hypericum perforatum on Wikimedia Commons
Hypericum perforatum on www.hypericum.com
Hypericum perforatum on the USDA Forest Service's Fire Effects Information Database
Hypericum perforatum on sites.duke.edu (PDF assessing the possible role of St. John’s Wort in the treatment of depression)
Hypericum perforatum description by Thomas H. Kent, last updated 12 Oct 2018.