Rare Species Guide

  Basis for Listing

Eleocharis nitida (neat spikerush) is primarily a species of boreal habitats in Canada. It is very rare in the lower forty-eight states and is listed as endangered in Wisconsin and Michigan. In Minnesota, it is localized in the northeast corner of the state (Laurentian Mixed Forest Province). When it was designated a state threatened species in 1996, it was known from just six historical records, only two of which had been relocated. Since that time, a renewed interest in the species has resulted in the discovery of many additional populations. We now know that E. nitida is more common and widely distributed in Minnesota than was formerly believed, and threatened status is no longer necessary. For that reason, it was down-listed to special concern status in 2013.

  Description

Culms 3-20 cm (1-8 in.) long and 0.15-0.30 mm (0.06-0.12 in.) thick. Rhizomes coarse and scaly, to 10+ cm (4+ in.) long. Leaves 2 per culm, reduced to bladeless sheaths. Spikelets 2.0-4.5 mm (0.8-1.8 in.) long, with 5-30 flowers. Floral scales red-brown to purplish, 1.0-1.5 mm (0.04-0.06 in.) long, deciduous. Perianth bristles absent. Achenes bright golden-yellow, trigonous, 0.7-0.8 mm (0.03 in.) long (excluding tubercle); surface with a finely pitted or honeycombed pattern visible (barely) at 10x, persistent after the scales fall. Tubercle distinct from the achene, depressed, 0.1-0.2 mm (0.004-0.008 in.) high, at least twice as wide as high, maturing mid-June to mid-October.

Eleocharis nitida is a small and delicate plant, with very thin, wiry culms and a coarse, prominent rhizome. It has bright golden-yellow achenes, each with a small black cap as the tubercle. Like the more common E. elliptica (elliptic spikerush), the scales of E. nitida are deciduous – they drop from the spikelet early, leaving the bright yellow achenes still tightly packed in the spikelet and easily visible. These are the only two Eleocharis in Minnesota that have this trait, and it may require careful measurements to tell the two apart.  The culms of E. nitida are 0.15-0.30 mm (0.006-0.01 in.) wide and 3-20 cm (1-8 in.) long; while the culms of E. elliptica are 0.4-0.9 mm (0.02-0.04 in.) wide and 10-65 cm (4-26 in.) long.  The achenes of E. nitida are also smaller than those of E. elliptica (0.6-0.8 mm vs. 0.8-1.1 mm) (0.24-0.31 in. vs. 0.31-0.43 in.).

  Habitat

Eleocharis nitida is an effective, though perhaps timid, colonizer of small wet localized depressions, such as shallow ditches, pits, trails, and wheel ruts in sand, gravel, or clay. It is also found at the margins of alder swamps and sedge meadows when a patch of wet soil is opened up for colonization. These are temporary or seasonal wetlands, in the sense they may become dry or dryish at some time during the course of a year.

  Biology / Life History

Eleocharis nitida is a low-growing rhizomatous sedge. Defining populations is difficult because patches of plants may be spatially small, yet can produce thousands of stems and tens of thousands of seeds. The species appears to be rather mobile, indicating the seeds are sometimes transported significant distances, likely by water, and can possibly remain dormant until favorable conditions develop.

  Conservation / Management

Potential threats are difficult to assess because this species requires dynamic habitats and ecotones, sometimes associated with both human activities and natural processes. While it would be misleading to suggest that this species prefers habitats disturbed by human activities, such as logging, road building, and land clearing, E. nitida does manage to maintain a short-term presence under those circumstances. Yet the natural equivalent of human alterations to the landscape, such as beaver activity, wind and ice storms, fires, and floods probably offer a better range of habitats and more consistently favorable conditions.

  Best Time to Search

The best time to search for E. nitida is when achenes are mature, from July to the middle of September.

  Conservation Efforts in Minnesota

Minnesota Biological Survey work and U.S. Forest Service Surveys have resulted in the discovery of new sites, many of which occur inland from Lake Superior in rather remote areas. Several populations occur in state forests and in state parks.

  References and Additional Information

Lakela, O. 1947. The occurrence of Eleocharis nitida in the Lake Superior region. Rhodora 49:81-82.

Minnesota Department of Natural Resources. 2003. Field guide to the native plant communities of Minnesota: the Laurentian mixed forest province. Ecological Land Classification Program, Minnesota County Biological Survey, and Natural Heritage and Nongame Research Program. Minnesota Department of Natural Resources, St. Paul, Minnesota. 352 pp.

Minnesota Department of Natural Resources, Division of Ecological Resources. 2008. Rare species guide: an online encyclopedia of Minnesota's rare native plants and animals [Web Application]. Minnesota Department of Natural Resources, St. Paul, Minnesota. Accessed 1 July 2009.

Minnesota Department of Natural Resources, Division of Fish and Wildlife. 1995. Statement of need and reasonableness in the matter of proposed amendment of Minnesota Rules, Chapter 6134: endangered and threatened species. Minnesota Department of Natural Resources, St. Paul, Minnesota. 336 pp.

Ownbey, G. B., and T. Morley. 1991. Vascular plants of Minnesota: a checklist and atlas. University of Minnesota Press, Minneapolis. 320 pp.

Smith, S. G., J. J. Bruhl, M. S. Gonzalez-Elizondo, and F. J. Menapace. 2002. Eleocharis. Pages 60-120 in Flora of North America Editorial Committee, editors. Flora of North America north of Mexico. Volume 23. Oxford University Press, New York, New York.

Smith, W. R. 2018. Sedges and rushes of Minnesota: the complete guide to species identification. University of Minnesota Press, Minneapolis. 696 pp.

U.S. Forest Service. 2000. Region 9 sensitive species list. U.S. Forest Service, Region 9, Superior National Forest, Duluth, Minnesota.