Eleocharis geniculata
Spike-rush

Key Characteristics

A relatively small, annual spike-rush of marshy lakeshores and low ground; forming tufts with erect to spreading, delicate stems 0.5 mm thick or less, ranging from 3-20 cm, achenes 2-sided and styles 2-cleft, summit of leaf sheaths not split, with shiny, dark, purplish achenes not over 1 mm long including the tiny tubercle

Status and Rank

  • State Status: X
  • State Rank: SX
  • Global Rank: G5

Occurrences

County NameNumber of OccurrencesYear Last Observed
Jackson11937
Washtenaw21936
Distribution map for Eleocharis geniculata

Updated 1/31/2017. Information is summarized from MNFI's database of rare species and community occurrences. Data may not reflect true distribution since much of the state has not been thoroughly surveyed.

Habitat

Typically found along marshy, alkaline lakeshores, and in low ground with fen associates.

Natural Community Types

Methodology

For each species, lists of natural communities were derived from review of the nearly 6,500 element occurrences in the MNFI database, in addition to herbarium label data for some taxa. In most cases, at least one specimen record exists for each listed natural community. For certain taxa, especially poorly collected or extirpated species of prairie and savanna habitats, natural community lists were derived from inferences from collection sites and habitat preferences in immediately adjacent states (particularly Indiana and Illinois). Natural communities are not listed for those species documented only from altered or ruderal habitats in Michigan, especially for taxa that occur in a variety of habitats outside of the state.

Natural communities are not listed in order of frequency of occurrence, but are rather derived from the full set of natural communities, organized by Ecological Group. In many cases, the general habitat descriptions should provide greater clarity and direction to the surveyor. In future versions of the Rare Species Explorer, we hope to incorporate natural community fidelity ranks for each taxon.

Associated Plants

No associate data are known for the three historical state sites for this species. According to Swink and Wilhelm (1994), the species is no longer extant in the Chicago area, but persists in nearby areas in Indiana, where the typical associates include nut-sedge, spike-rush, rush, Canada rush, Kalm's lobelia, common water-horehound, beak-rush, and arrow-grass.

Management

Protect habitat from direct destruction, excessive use of herbicides, and competitive exotic species such as purple loosestrife. Non-point source pollution, such as nutrient enrichment, that pollutes aquatic environments and degrades water quality is also likely detrimental to this species.

General Survey Guidelines

Random meander search covers areas that appear likely to have rare taxa, based on habitat and the judgement of the investigator.

Survey Methods

Page Citation

Michigan Natural Features Inventory. 2007. Rare Species Explorer (Web Application). Available online at http://mnfi.anr.msu.edu/explorer [Accessed May 23, 2017]

References

Survey References

Technical References

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