Spikes:

Separate staminate (male) and pistillate (female) spikes, with 2 to 4 staminate spikes to 1¼+ inches long at the tip of the stem, sometimes with a few pistillate flowers at the tip (gynecandrous) or the base (androgynous) or otherwise mixed. Well-separated from the staminate spikes are 1 to 3 pistillate spikes, occasionally with a few staminate flowers at the tip, each 1 to 3 inches long, cylindric, 5 to 15 mm (to ~½ inch) in diameter, short-stalked to stalkless, mostly erect to ascending. At the base of each pistillate spike is a leaf-like bract; that of the lowest spike is up to 20 inches long, over-topping the terminal spike.

Leaves and stems:

Leaves are basal and alternate, mostly flat, 1.8 to 7 mm wide, the upper stem leaves often over-topping the terminal spike. Stem leaf sheaths are straight across to concave at the tip, thin, whitish to light brown and may shred with age, forming a ladder shape of fibers (ladder fibrillose). The ligule (membrane where the leaf joins the sheath) is much longer than wide. Leaves are hairless, erect to arching, and have distinct cross partitions between the veins (septate-nodulose), especially on the sheaths.

Bases are wrapped in a reddish-brown to purplish sheath that becomes fibrous, with some old leaves persisting from the previous season. Stems are ascending to arching, 3-sided in cross-section, and rough along the angles on the upper stem. Stems can elongate up to about 3 feet at maturity. Plants form dense clumps from short rhizomes.

Fruit:

Fruit develops in late spring to mid-summer, the pistillate spikes forming clusters of seeds (achenes), each wrapped in a casing (perigynium), subtended by a scale. Perigynia are ascending and tightly packed on the spike. Each pistillate spike contains 30 to 100 fruits.

Pistillate scales are lance to egg-shaped, white to brown tinged to purplish, pointed or with a long taper to a pointed tip, much narrower and mostly shorter than the perigynia. Perigynia are 4 to 7.5 mm long, 1.7 to 3.5 mm wide, greenish to straw-colored to brown at maturity, hairless, distinctly 7 to 12-veined, thin, much inflated, the body lance to egg-shaped, mostly broadest below the middle, tapering to a smooth beak 1.1 to 2.6 mm long that has 2 erect to slightly spreading teeth at the tip. Achenes are 3-sided, yellowish to light brown at maturity, elliptic to urn-shaped with a persistent style.

Notes:

Carex vesicaria is an occasional to common sedge of wet meadows and depressions, lake and pond shores, and other swampy places in about half of Minnesota, sometimes in areas subject to spring flooding but dry out in summer.

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 vesicaria is in the Vesicariae section; some of its common traits are: clump forming or not, rhizomatous, hairless leaves, basal sheaths brown or red-purple, sheaths often splitting into fibers and forming a ladder shape, sheaths with cross partitions between veins (septate-nodulose), 2 to 10 spikes, terminal spike all-staminate, leaf-like bract subtending the lowest pistillate spike, perigynia mostly ascending to spreading, hairless, mostly egg to teardrop shaped, beaked and toothed, at least slightly inflated, achenes 3-sided in cross-section with a persistent style.

Carex vesicaria is distinguished from all other Minnesota sedges by the combination of: densely clump-forming, reddish to purple basal sheaths that are often fibrous, ligules much longer than wide, 2 to 4 staminate spikes, 1 to 3 cylindric short-stalked to stalkless pistillate spikes 1 to 3 inches long, perigynia much inflated, to 7.5 mm long, distinctly 7 to 12-veined and beaked, 3-sided achenes that have a persistent style and are not dented on one side. While there are similarities with other members of Vesicariae, the spikes of C. vesicaria most closely resemble those of Carex rostrata and Carex utriculata, both of which are colony-forming from long rhizomes and not densely clump-forming, and do not have fibrous sheaths or purplish basal sheaths. C. vesicaria may hybridize with C. utriculata and C. hystericina, but this is rare.