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MARSH ST. JOHNSWORT

NOMENCLATURE

Other Names:

Scientific Name: Triadenum virginicum L.

 Plant Family: Guttiferae

GENERAL INFORMATION

Botanical Description: herbaceous

 Stems: erect, smooth, reddish, 6 -18 inches tall, lightly branched

 Leaves: opposite, ovate or oblong, attached directly to stem, margins smooth

 Roots:

Flowers: long and to 0.5 inch across, pink or red-purple, in leaf axils and on branch terminals; fruit is a cylindrical, oval-shaped capsule

Seeds: Found in a dry capsule that is oval to oblong, about 0.5 inch long.

 Seedling:

ECONOMIC IMPORTANCE

May be difficult to control once invasion has occurred.

LIFE CYCLE

Reproduction: perennial

 Propagation: seed, underground rootstocks

 Dispersal:

DISTRIBUTION

State: Found throughout Wisconsin.

 National: Found in bogs and marshes in many lowland areas east of Mississippi River.

 Origin: native of Europe

ENVIRONMENTAL FACTORS

Common in cranberry beds and wild bog. Generally appears along cranberry bed edges first, invading inward.

SCOUTING PROCEDURE/ET

While scouting a cranberry bed for disease and insect pests, identify weed populations as they arise. Note the specie(s) of weed present as well as the population level relative to field area. Example: 10% marsh st. johnswort, 20% boneset and joe-pye weed mix.

REFERENCES

Dana, M. 1987. Cranberry Weeds in Wisconsin. Department of Horticulture, University of Wisconsin-Madison. Madison, Wisconsin. p. 20.

 

Gleason, H. A. 1952. Illustrated Flora of the United States and Adjacent Canada. Vol 2. Lancaster Press, Lancaster, Pennsylvania. p. 545.

Kummer, L. D., T. G. Dittl, and T. D. Planer. 1993. Wisconsin Cranberry Weeds. Wisconsin Cranberry Board, Wisconsin Rapids, Wisconsin. p. 6.

 

Lorenzi, H. J. and L. S. Jeffery. 1987. Weeds of the United States and Their Control. Van Nostrand Reinhold Company, New York, New York. p. 211.

 

McGregor, R. L. 1986. Flora of the Great Plains. University Press of Kansas, Lawrence, Kansas. p. 239.

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