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Kevin Doyle

Robbins' Spike-rush (Eleocharis robbinsii)

Life history

Species overview

Robbins' Spike-rush (Eleocharis robbinsii), a Wisconsin Special Concern plant, is found forming beds in the shallows of soft-water ponds and lakes; these areas are characteristic of lagoons on the Apostle Islands. Blooming occurs late June through late July; fruiting occurs early July through late September. The optimal identification period for this species is late July through early September.

Synonyms: None


  • Distinguishing characteristics: Triangular stems; spikelet 1 to 2.5 cm.
  • Flower characteristics: Spikelets lance-shaped, 1 to 2 cm long and 2 to 3 mm wide, barely wider than stems; sepals and petals reduced to 6 barbed bristles; style 3-parted.
  • Fruit characteristics: Achenes rounded on both sides, light brown, 2 to 3 mm long; tubercle flattened and cone-shaped, with a raised ring at base.
  • Leaf characteristics: Stems slender, 3-angled, 2 to 6 dm long and 1 to 2 mm wide; sheaths brown; when underwater, plants often with numerous sterile stems from base.


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


  • Growth form: Graminoid
  • Vegetative reproduction: Rhizomatous
  • Life cycle: Perennial
  • Comments: Associated Species: Potamogeton spp., Brasenia schreberi, Nuphar spp., Nymphaea spp., Eriocaulon septangulare.

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 Robbins' Spike-rush (Eleocharis robbinsii). 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 robbinsii in the Natural Heritage Inventory Database as of July 2015.

Summary Information
State StatusSC
Federal Status in Wisconsinnone
State RankS3
Global RankG4G5
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 forming beds in the shallows of soft-water ponds and lakes; these areas are characteristic of lagoons on the Apostle Islands.
  • Soils: Wet soils.

Natural communities

This table lists the natural communities that are associated with Robbins' 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 Robbins' 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

  • Minimize disturbance to hydrology, including soil disturbance from rutting.
  • Prescribed burns and/or brushing may be beneficial (dependent on local site conditions).
  • 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.


Robbins' Spike-rush Photo.

Photo by Kevin Doyle, Wisconsin DNR.

Robbins' Spike-rush Photo.

The culms of Eleocharis robbinsii are separate all the way to the base whereas the culms of the similar looking Schoenoplectus subterminalis have sheaths, which wrap around the adjacent culm.

Photo © Catherine Higley.

Robbins' Spike-rush Photo.

The infloresensce of Eleocharis robbinsii is no wider than the stem of the plant and can even be overlooked as separate from it.

Photo © Catherine Higley.

Robbins' Spike-rush Photo.

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: 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