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Capitate Spike-rush (Eleocharis flavescens var. olivacea)

Life history

Species overview

Capitate Spike-rush (Eleocharis flavescens var. olivacea), a State Special Concern plant, is found on sandy, mucky, or peaty shorelines, as well as bog and poor fen mats. Blooming occurs throughout June; fruiting occurs throughout July. The optimal identification period for this species is late June through late July.

Synonyms: Eleocharis flavescens var. olivacea, E. flaccida var. olivacea


  • Distinguishing characteristics: Distinguished by the combination of its spikelet that is wider than the stem, achene which is lenticular (2-parted style) and leaf sheath, which is membranous and cleft on one side.
  • Flower characteristics: Spikelets ovate, 2 to 7 mm long and much wider than stem; sepals and petals reduced to 6 to 8 barbed bristles; style 2-parted (rarely 3-parted).
  • Fruit characteristics: Achenes lens-shaped, brown, 1 mm long; tubercle pale, cone-shaped, constricted at base.
  • Leaf characteristics: Stems bright green, flattened, 3 to 15 cm long.


  • Blooming phenology: throughout June
  • Fruiting phenology: throughout July
  • Optimum time to identify: late June through late July


  • Growth form: Graminoid
  • Vegetative reproduction: Stoloniferous
  • Life cycle: Perennial
  • Comments: Associated Species: Scirpus smithii, S. hudsonianus, Eleocharis intermedia, E. acicularis, Larix laricina, Picea mariana, Carex livida.

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 Capitate Spike-rush (Eleocharis flavescens var. olivacea). 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 Eleocharis flavescens var. olivacea in the Natural Heritage Inventory Database as of March 2012.

Summary Information
State StatusSC
Federal Status in Wisconsinnone
State RankS2
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 on sandy, mucky, or peaty shorelines, as well as bog and poor fen mats.
  • Soils: Wet, sandy or peaty soils.

Natural communities

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

Map of the Ecological Landscapes of Wisconsin.

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

  • 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.
  • This species is likely sensitive to water quality. Following BMPs around streams and buffering associated drainages will reduce eutrophication and prevent water quality degradation.
  • Maintain and restore open habitat through selective clearing and brushing.
  • Prescribed burns and/or brushing may be beneficial (dependent on local site conditions).
  • Minimize disturbance to hydrology, including soil disturbance from rutting.


Capitate Spike-rush  [Photo #23439]

Photo © Emmet Judziewicz.

Capitate Spike-rush  [Photo #23440]

Photo © Emmet Judziewicz.

Capitate Spike-rush  [Photo #23441]

Photo © Emmet Judziewicz.

Capitate Spike-rush  [Photo #23442]

Photo © Emmet Judziewicz.

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: Tuesday, October 07, 2014
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