Triadenum virginicum (L.) Raf.
Family: Hypericaceae
Virginia marsh St. Johnswort
[Elodea campanulata ,  more]
Triadenum virginicum image
Paul Rothrock  
Annual or perennial herb 30 cm - 0.6 m tall Leaves: opposite, stalkless, 3 - 6 cm long, two to three times longer than wide, oblong to egg-shaped or elliptic with a more or less heart-shaped base and a rounded or notched tip, non-toothed, dotted with dark spots and translucent glands beneath. Flowers: borne in axillary or terminal clusters, with 5 - 8 mm long sepals that are lance-shaped with a pointed tip, five pinkish petals 8 - 10 mm long, 2 - 3 mm long styles, and nine stamens forming three groups of three that alternate with three glands. Fruit: a three-chambered capsule, 8 - 12 mm long, cylindrical but tapering near the tip, many-seeded. Stems: erect.

Similar species: Triadenum fraseri has 3 - 5 mm long sepals at maturity, blunt or rounded sepal tips and 0.5 - 1.5 mm long styles.

Flowering: late July to early September

Habitat and ecology: Local in the eastern part of the Chicago Region, especially boggy areas close to Lake Michigan.

Occurence in the Chicago region: native

Etymology: Virginicum means "from Virginia."

Author: The Morton Arboretum

Erect, rhizomatous perennial, 3-6 dm; lvs 3-6 cm, oblong to ovate-oblong or elliptic, 2-3(-4) times as long as wide, rounded or retuse above, cordate or subcordate at the sessile base, dark-punctate beneath, dotted with translucent glands; sep lanceolate, acute or acuminate, 5-8 mm; pet 8-10 mm; fr trilocular, cylindric, 8-12 mm, gradually tapering to the 2-3 mm styles; 2n=38. Bogs, marshes, and wet shores; N.S. to Fla. and Miss., mostly near the coast, or inland at low altitudes across N.Y. to s. Ont., O., and the s. end of Lake Michigan. July, Aug. (Hypericum v.)

Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.

©The New York Botanical Garden. All rights reserved. Used by permission.
From Flora of Indiana (1940) by Charles C. Deam
Frequent to infrequent in the interdunal flats about Lake Michigan and on the marshy borders of lakes and in swamps throughout the lake area.