Triadenum fraseri (Fraser's Marsh St. Johnswort)
|Also known as:||Bog St. John's-wort|
|Family:||Hypericaceae (St. John's-wort)|
|Habitat:||part shade, sun; wet; bogs, marshes, fens, along shores|
|Bloom season:||July - August|
|Plant height:||1 to 2 feet|
|Wetland Indicator Status:||none|
|MN county distribution (click map to enlarge):|
|National distribution (click map to enlarge):|
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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:
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.
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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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?