Life history

Species overview

Swan Sedge (Carex swanii), a Wisconsin Special Concern plant, is found most often in oak savannas and open, sandy oak woodlands, as well as in southern mesic forests. It is sometimes reported at moist margins where these habitats transition to shrub-carr. Blooming occurs late May through early June; fruiting occurs throughout June. The optimal identification period for this species is throughout June.

Synonyms: Carex virescens var. swanii

Identification

• Distinguishing characteristics: Cespitose; leaves and sheaths pubescent, longer than the culm; terminal spike mostly pistillate, staminate at base; perigynia pubescent, ascending, obovate-circular; beak absent.
• Flower characteristics: Basal lateral spikes distant; terminal spike pistillate, at least half flowers female, staminate at the base.
• Fruit characteristics: Perigynia ascending, obscurely 5 to 13-veined, obovate-circular, trigonous in cross section, densely pilose; beak absent.
• Leaf characteristics: Leaf blades pubsescent, longer than the culm; ligules longer than wide.

Phenology

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

Other

• Growth form: Graminoid
• Vegetative reproduction: Rhizomatous
• Life cycle: Perennial
• Section: Porocystis
• Comments: Associated Species: Quercus velutina, Schizachyrium scoparium, Liatris aspera, Prunus virginiana, Tradescantia ohioensis, Potentilla simplex, Lechea minor.

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 Swan Sedge (Carex swanii). 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.

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 most often in oak savannas and open, sandy oak woodlands, as well as in southern mesic forests. It is sometimes reported at moist margins where these habitats transition to shrub-carr.
• Soils: Dry, sometimes sandy soils.

Natural communities

This table lists the natural communities that are associated with Swan Sedge. 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 Swan Sedge. The scores (3=High, 2=Moderate, 1=Low, 0=None) also correspond to the map.

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 broadcast spraying of herbicides; use care with spot spraying.
• 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.

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).
• Minimize disturbance to hydrology, including soil disturbance from rutting.
• Maintain and restore open habitat through selective clearing and brushing.

Other resources

Links to additional Swan Sedge information

Other links related to vascular plants (all exit the DNR website)

• Wisconsin Flora
• NatureServe Explorer
• Atlas of Wisconsin Prairie and Savanna Flora - Wisconsin State Herbarium
• USDA - NRCS Plants Database
• USGS Midwestern Wetland Flora - field office guide to plant species
• eFloras
• Cofrin Center for Biodiversity Herbarium
• Intermountain Herbarium Grasses of North America
• Orchids of Wisconsin

Photos

Click to view a larger version. Please considering donating a photo to the Natural Heritage Conservation Program for educational uses. Photo use