PROTECTING WISCONSIN'S BIODIVERSITY

 
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Scientific Name Common Name Global Rank State Rank Federal Status WI Status

Horsetail Spike-rush (Eleocharis equisetoides)

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Photo by Susan Knight

 

Counties with Mapped NHI Occurrences

Horsetail Spike-rush (Eleocharis equisetoides), a Wisconsin Special Concern plant, is found in the shallow water of emergent marshes, lakeshore edges, and ponds. The single extant Wisconsin occurrence was found in approximately 60cm of water in a marl lake with a muck/sand bottom. Blooming occurs July through September, fruiting late-July through September. The optimal identification period for this species is late-July through September.

Scirpus equisetoides

 
 
 
Identification

Horsetail spikerush is a graminoid with 3-8 stramineous to reddish, slender, vestigial to 2.5 mm, perianth bristles that are shorter than to equaling achene, and smooth or obscurely retrorsely spinulose. Anthers are stramineous to red-striated, 2.6-3.2mm, it has 2-3 styles. Its fruit are yellowish to reddish brown achenes that are obovoid, biconvex to obscurely compressed trigonous, 1.8-2.3mm x 1.4-1.9mm, obscurely sculptured or sometimes partially smooth at 10-15X, each face has 20-40 rows of linear, transversely elongated cells, lines separating cells obscure, apex has a very short neck 0.6-0.8mm wide. Tubercles are dark brown, lamelliform, high-deltoid, and 0.6-1.1mm x 0.5-0.7 mm. Its distal leaf sheaths are persistent, membranous to thinly papery, the apex is acute to slightly acuminate.

It is distinguished from other Eleocharis species by its spikelets, which are 3-8mm wide (not wider than culm), and its culms, which are hollow, with complete transverse septa (mostly evident externally).

Phenology and Reproduction

Rhizomatous. Blooming occurs July through September, fruiting late-July through September.

Perennial. The optimal identification period for this species is late-July through September.

Ecology and Associated Species

Associated species include Chara, Elodea canadensis, Schoenoplectus tabernaemontani, and filamentous algae.

Habitat

Horsetail spike-rush is found in the shallow water of emergent marshes, lake edges, and ponds. The single extant Wisconsin occurrence was found in ~60cm of water in a marl lake with a muck/sand bottom.

Avoidance Measures and Management Guidance

Avoid broadcast spraying of herbicides and use care with spot spraying.

Minimize disturbance to hydrology, including soil disturbance from rutting.

Maintain and restore open habitat through selective clearing and brushing.

This species is likely sensitive to water quality. Following BMPs around streams and buffering associated drainages will reduce eutrophication and prevent water quality degradation.

Wildlife Action Plan

Species of Greatest Conservation Need (SGCN) are associated with habitats (or natural communities) and places on the landscape. Understanding relationships among SGCN, natural communities and ecological landscapes help us make decisions about issues affecting SGCN and their habitat and how to respond. Download the Wildlife Action Plan association score spreadsheet to explore rare species, natural communities and ecological landscape associations

Conservation actions respond to issues or threats, which adversely affect species of greatest conservation need (SGCN) or their habitats. Besides actions such as restoring wetlands or planting resilient tree species in northern communities, research, surveys and monitoring are also among conservation actions described in the Wisconsin Wildlife Action Plan because lack of information can threaten our ability to successfully preserve and care for natural resources.

For more information, contact

Kevin Doyle
Conservation Biologist
tel:+1-608-416-3377