Flower:

A single spike at the top of the stem, narrowly lance-elliptic in outline, pointed at the tip, 3 to 8 mm (to ~1/3 inch) long, with 3 to 10 florets spirally arranged, each floret subtended by a single scale. Scales are 2.5 to 6 mm long, 1.5 to 2.5 mm wide, blunt to pointed at the tip, orange-brown to purple-brown with a green midrib that dries brown. Florets have a 3-parted style and 3 stamens. The lowest scale in the spike is similar to the rest, is at least half as long as the spike, and has a flower.

Leaves and stems:

The 2 leaves are bladeless and reduced to sheaths on the lower stem. The upper sheath is membranous to papery, straw-colored to brown to reddish towards the base, green to straw-colored to brown towards the tip, the front nearly straight across to pointed at the tip, without a conspicuous tooth at the apex. Stems are erect, round to slightly compressed in cross-section, wiry, .2 to .5 mm diameter (rarely to 1+ mm), usually with several vertical ridges that may not be obvious until the stem dries. Plants form small clumps and colonies from slender rhizomes, the rhizomes forming bulbs at the tip from which new stems emerge.

Fruit:

Each flower produces a single achene (seed), that drops off independently of the scale, the achene with a cap-like appendage (tubercle) at the tip that appears to be a continuation of the achene, though may be a different color. Achenes are 1.6 to 2.3 mm long, .7 to 1.3 mm wide, straw-colored to brown to gray-brown, minutely pitted across the surface, 3-sided in cross-section, urn-shaped in outline, rounded at the tip end and tapering at the base. Tubercles are pale to dark brown, pyramidal, .3 to .4 mm long, longer than wide. There is no neck or constriction between the top of the achene and the base of the tubercle. Surrounding the achene are usually 3 to 6 (sometimes 0) barbed, brown bristles, often unequal in length, varying from much shorter than to about as long as the achene.

Notes:

Eleocharis quinqueflora is one of several rare Spikerushes in Minnesota, found in calcareous fens, sedge meadows, floating peat mats, and sandy or marly seeps and shores. According to the DNR, it is absent from the majority of fens and its known populations are small, transient, and sensitive to a range of ecological disturbances. It was listed as a Special Concern species in 1984, and is also currently a Special Concern species in Wisconsin. E. quinqueflora superficially resembles other colony-forming Spikerushes, but is distinguished by the combination of: wiry stems usually less than 1 mm wide, few-flowered spikes, the lowest scale is similar to the rest, at least half as long as the spike and has a flower, 3-sided achenes minutely pitted on the surface with a pyramidal tubercle that appears to be a continuation of the achene, and is found primarily in mineral-rich fens.