Triadenum fraseri (Fraser's Marsh St. Johnswort)

Plant Info
Also known as: Bog St. John's-wort
Family:Hypericaceae (St. John's-wort)
Life cycle:perennial
Habitat:part shade, sun; wet; bogs, marshes, fens, along shores
Bloom season:July - August
Plant height:1 to 2 feet
Wetland Indicator Status:GP: OBL MW: OBL NCNE: OBL
MN county distribution (click map to enlarge):Minnesota county distribution map
National distribution (click map to enlarge):National distribution map

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Detailed Information

Flower: Flower shape: 5-petals Flower shape: indistinct Cluster type: flat

[photo of flowers] Clusters of a few to several flowers arising from leaf axils, at the end of branching stems, and at the top of the plant, though it is a challenge to catch the blooms when they are open. Flowers are ¼ to ¾ inches wide when fully open, with 5 pink petals and 9 or 12 yellow-tipped stamens surrounding a greenish style. The sepals cupping the flower are green or purplish with blunt or pointed tips, and half as long as the petals, or more.

Leaves and stems: Leaf attachment: opposite Leaf type: simple

[photo of leaves] Leaves are oval to egg-shaped to rounded triangular, to 2½ inches long and 1¼ inches wide, toothless and hairless, with a rounded tip, rounded base and no leaf stalk, the larger leaves somewhat clasping the stem and often angled up. Color is blue-green, sometimes tinged purple. The underside of leaves is dotted with brown or black glands. Stems are often reddish. The plant may be erect but often leans over.

Fruit: Fruit type: capsule/pod

[photo of fruit] Fruit is a dark red, 3-sectioned capsule ¼ to ½ inch long, oval to cylindrical, abruptly tapered to a sharply pointed tip.


It is a rare event to find Marsh St. Johnswort with open flowers. It is more commonly IDed by the leaves and the maroon fruit, which might be mistaken for flower buds. On a trip to northern Beltrami County in early July, we got very lucky to find a number of flowering plants that had not yet developed fruit. This species also goes by Latin name Hypericum virginicum but the accepted name in Minnesota is Triadenum fraseri. Along with all Hypericum species, it switched from the Clusiaceae family to Hypericaceae

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More photos

Photos by K. Chayka taken in Anoka and Beltrami counties. Photos courtesy Peter M. Dziuk taken in Anoka County.


Have you seen this plant in Minnesota, or have any other comments about it?

Posted by: Brett W - Anoka Sand Plain
on: 2020-07-29 22:40:33

In Uncas Dunes SNA (main unit) and found a flowering plant in a Blaine public park yesterday in flower!

Posted by: Timothy Johnson
on: 2020-12-30 11:53:14

Last of the blossoms opening August 23, 2017 in Blaine Preserve SNA.

Posted by: Madison rose
on: 2021-08-20 05:42:42

Is this genus of St. John's wort edible / safe for consumption (besides the berries) or hold the same properties as perforate St. John's wort? (Ie. mood stability). I can't seem to find anything on this beautiful little plant other then your website!

Posted by: K. Chayka
on: 2021-08-20 07:43:41

Madison, we have no information regarding edible or medicinal uses of this plant, but since it is a different genus we suspect there are few, if any, similarities in that regard. BTW, it does not produce berries?the capsules are not fleshy and only contain dry seeds.

Posted by: Brett W - Mille lacs WMA
on: 2023-09-17 16:41:31

Found a few in a Spruce big.

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