Spikes:

Separate staminate (male) and pistillate (female) spikes, with a single staminate spike to ¾ inch long at the tip of the stem. Below the staminate spike are 1 to 3 widely spaced pistillate spikes that often have a few staminate flowers at the tip (androgynous). The lowest spike is often on a slender, nodding stalk with the upper on shorter, erect stalks, each with an erect, leaf-like bract with a blade usually shorter than the attending spike, and a loose sheath that is translucent white on the front and up to about 1 inch long.

Leaves and stems:

Leaves on flowering stems are few, alternate on the lower stem, mostly erect, less than 4 inches long, 2 to 5 mm wide, and flat. Stem leaf sheaths are loose, translucent white. The ligule (membrane where the leaf joins the sheath) is longer than wide but inconspicuous. Vegetative shoots are leafier with floppy blades up to 16 inches long.

Bases are wrapped in a brown sheath that is bladeless or very short-bladed and not fibrous. Stems are single or a few together, slender, erect to ascending, 3-sided, smooth, elongating up to 24 inches at maturity and longer than the leaves. Plants form loose colonies from long rhizomes.

Fruit:

Fruit develops in late spring to early summer, the pistillate spikes forming clusters of seeds (achenes), each wrapped in a casing (perigynium), subtended by a scale. Pistillate spikes each contain 3 to 15 fruits that are ascending and usually loosely arranged, especially at the base of the spike, sometimes more crowded and overlapping towards the tip.

Pistillate scales are oval to egg-shaped, blunt to pointed at the tip, purplish-brown with a broad green midrib, narrower than the perigynia and half to ¾ as long. Perigynia are 3.5 to 5 mm long, 1.5 to 2.2 mm wide, green to brown at maturity, veinless or obscurely veined, hairless, loosely wrapping the achene, obscurely 3-sided to nearly round in cross-section, the body oval-elliptic to egg-shaped, abruptly tapering to a slender beak at the tip that is about 1 mm long, slightly bent, and minutely toothed. Achenes are 2.2 to 3 mm long, 3-sided with concave sides in cross-section, and light to dark brown at maturity.

Notes:

Carex vaginata is an occasional sedge of shaded swampy or boggy places, typically found growing on mossy hummocks. It has a circumpolar distribution and reaches the southern edge of its range in northern Minnesota.

Carex is a large genus, with over 600 species in North America and 150+ in Minnesota alone. They are grouped into sections, the species in each group having common traits. Carex vaginata is in the Paniceae section; some of its common traits are: clump forming or not, rhizomatous, hairless leaves, basal sheaths brown or red-purple, sheaths sometimes fibrous, 2 to 4 spikes, terminal spike all-staminate, lateral spikes all-pistillate and stalked, leaf-like bract subtending the lowest pistillate spike with a sheath more than 4 mm long, perigynia ascending to spreading, hairless, weakly 3-sided to round in cross-section, beaked or not, at least slightly inflated, achenes 3-sided in cross-section.

Carex vaginata is a distinctive species and should not be confused with other Minnesota sedges, distinguished by the combination of: stems single or just a few together; a single terminal staminate spike; 1 to 3 widely spaced pistillate spikes, often with a few staminate flowers at the tip; long-sheathing bracts with a short leaf-like blade; 3 to 15 perigynia per spike (usually) loosely arranged; perigynia slightly inflated, up to 5 mm long, oval-elliptic with a slender, slightly bent beak; achenes 3-sided with concave sides. The distinctive bracts are recognizable even after the perigynia has dried up and dropped off.