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Round-fruited St. John's Wort (Hypericum sphaerocarpum)

Life history

Species overview

Round-fruited St. John's Wort (Hypericum sphaerocarpum), a Wisconsin Threatened plant, is found in wet prairies and moist sites subject to disturbance. Blooming occurs late June through early August; fruiting occurs late July through late August. The optimal identification period for this species is late June through late August.

Synonyms: Hypericum sphaerocarpum var. turgidum, Hypericum turgidum


  • Distinguishing characteristics: Sepals equal or nearly so, 2.5 to 5 mm; 45 to 85 stamens.
  • Flower characteristics: inflorescence branched and usually compact; sepals 2.5 to 5 mm; petals 5 to 9 mm; stamens 45 to 85; stigmas 3 or 4, minute.
  • Fruit characteristics: Ovoid, 5 to 7 mm, slender beaked, strictly unilocular; seeds 2 to 2.7 mm.
  • Leaf characteristics: Linear oblong to narrowly elliptic, 3 to 7 cm long by 5 to 15 mm wide, with or without evident lateral veins, acute or obtuse, tapering to the base.


  • Blooming phenology: late June through early August
  • Fruiting phenology: late July through late August
  • Optimum time to identify: The optimal identification period for this species is late June through late August


  • Growth form: Forb-erect
  • Vegetative reproduction: Rhizomatous
  • Life cycle: Perennial
  • Comments: Associated Species: Quercus macrocarpa, Salix spp., Potentilla arguta, Eryngium yuccifolium, Ratibida pinnata, Cornus racemosa, Teucrium canadense

State status

Status and Natural Heritage Inventory documented occurrences in Wisconsin

The table below provides information about the protected status - state and federal - and the rank (S and G Ranks) for Round-fruited St. John's Wort (Hypericum sphaerocarpum). See the Working List Key for more information about abbreviations. Counties shaded blue have documented occurrences for this species in the Wisconsin Natural Heritage Inventory database. The map is provided as a general reference of where this species has been found to date and is not meant as a range map.

Documented locations of Hypericum sphaerocarpum in the Natural Heritage Inventory Database as of July 2015.

Summary Information
State StatusTHR
Federal Status in Wisconsinnone
State RankS1S2
Global RankG5
Tracked by NHIY

Habitats and landscapes

The Natural Heritage Inventory has developed scores indicating the degree to which each of Wisconsin's rare plant species is associated with a particular natural community or ecological landscape. This information is similar to that found in the Wildlife Action Plan for animals. As this is a work in progress, we welcome your suggestions and feedback.

General habitat information

  • Habitat description: Found in wet prairies and moist sites subject to disturbance.
  • Soils: Moist to wet soils.

Natural communities

This table lists the natural communities that are associated with Round-fruited St. John's Wort. Scores for natural community associations are: "significant" association (score=3), "moderate association" (score=2) or the species can be present but is only weakly associated with the community (score=1).

Ecological landscapes

This table lists the ecological landscape association scores for Round-fruited St. John's Wort. The scores (3=High, 2=Moderate, 1=Low, 0=None) also correspond to the map.

Map of the Ecological Landscapes of Wisconsin.

Ecological landscape score
Southeast Glacial Plains 3
Western Coulee and Ridges 1

Species guidance

The Endangered Resources Program has developed avoidance measures and management guidelines for plants on the Natural Heritage Working List. These are a work in progress, and we welcome your suggestions and feedback. Sources used in developing this information can be found here.

Avoidance measures

These are specific actions designed to avoid "take" (mortality) of this species.

  • Avoid known individual plant locations and conduct operations elsewhere when they are least likely to cause damage. Ideally, this would involve frozen, snow-covered ground. However, in areas of the state where frozen conditions are unreliable, very dry soils late in the growing season might be the best available alternative. Consult with a biologist, if needed.
  • Avoid broadcast spraying of herbicides; use care with spot spraying.

Management guidance

Management guidelines are additional considerations that may help maintain or enhance habitat for this species

  • Prescribed burns and/or brushing may be beneficial (dependent on local site conditions).
  • Maintain and restore open habitat through selective clearing and brushing.
  • Survey for and control invasive plants prior to conducting timber operations, as these can be spread by vehicles and often respond vigorously to increased light; see forestry BMPs for invasive species.
  • Minimize disturbance to hydrology, including soil disturbance from rutting.


Round-fruited St. John's Wort Photo.

Photo by Thomas Meyer, Wisconsin DNR.

Support for Wisconsin's rare plant information has been provided by the Division of Forestry, the Endangered Resources Fund and the Wisconsin Rare Plant Preservation Fund. To donate, visit the Natural Resources Foundation of Wisconsin [exit DNR].

Last revised: Wednesday, May 05, 2021
Southwest Savanna Southern Lake Michigan Coastal Western Coulees and Ridges Southeast Glacial Plains Central Sand Hills Central Lake Michigan Coastal Central Sand Plains Northern Lake Michigan Coastal Northern Lake Michigan Coastal Northeast Sands Western Prairie North Central Forest Northern Highlands Northwest Lowlands Northwest Sands Northwest Lowlands Superior Coastal Plains Forest Transition