Flower:

Inverted cone-shaped clusters, one at the stem tip and usually 2 lateral clusters, crowded or not, each 1.5 to 4 cm (~½ to 1½ inches) long and to 1.5 cm wide. Each cluster is stalked, the lateral stalks usually short and erect, or sometimes thread-like and drooping in shady locations. At the base of each cluster stalk is a leaf-like bract, the lowest bract largest, up to 4+ inches long and usually greatly over-topping the terminal cluster. Each cluster has 3 to 10 spikelets (flower clusters) of one to a few flowers each, usually a mix of staminate (male) and pistillate (female) flowers, sometimes a single sex.

Spikelets are erect to ascending, 3 to 9 mm long (to ~1/3 inch). Each flower is subtended by a scale; the lowest scales in a spikelet are often empty. Staminate flowers have 1 to 3 stamens, pistillate flowers have a 2 or 3-parted style on a round ovary. Scales are purple-spotted to brown, hairless to finely hairy, lance-shaped tapering to a pointed tip or the green midrib extending to a short awn.

Leaves and stems:

Leaves are alternate, erect to ascending to arching, hairless to finely hairy, rough along the edges and the midrib, M-shaped in cross-section, 3 to 9 mm wide, shorter than the flowering stem, the upper leaves not over-topping the terminal cluster. Leaf sheaths are closed, inverted U-shaped to nearly straight across at the tip, membranous with parallel veins on the front, green or purple-tinged. Stems are erect to arching, unbranched, sharply 3-sided in cross-section, hairless but slightly rough along the angles, and multiple from the base forming loose to dense clumps.

Fruit:

Pistillate flowers produce a single achene (seed), 2 to 3 mm long, oval to round, smooth and shiny on the surface, usually pearly white when mature, sometimes grayish-brown. Attached to the base is short structure called a hypogynium that is white to light brown and minutely pitted all across the surface.

Notes:

Scleria triglomerata is a rare sedge of sandy prairies and wetland edges and reaches the northern edge of its range in Minnesota. Here it is found primarily on the Anoka Sandplain in wet sedge meadows and at the edges of swales, though in other parts of its range it may also be found in open or shaded woods or even rocky, disturbed sites. According to the DNR, the handful of populations known prior to 1960 were mostly destroyed by development around the Twin Cities metro area; Helen Allison SNA and Cedar Creek Ecosystem Science Reserve, both in Anoka County, were thought to be the only remaining sites for many years, until a more thorough survey of the Anoka Sandplain discovered 4 more sites, one of which has already been destroyed. Two other sites have since been found, one each in Dakota and Washington counties. Scleria triglomerata was listed as a Minnesota Endangered species in 1984 and is currently a Special Concern species in Wisconsin.

At a casual glance it is similar to a Juncus or Rhynchospora species, both of which have perfect flowers rather than unisex and round or weakly 3-sided stems, but the smooth, shiny, round, white achenes make Scleria triglomerata stand out.