Spikes:

Separate staminate (male) and pistillate (female) spikes, with 1 to 3 staminate spikes crowded together at the tip of the stem, the terminal spike up to 2¼ inches long and the others much smaller. Below the staminate spikes are 1 to 3 widely spaced pistillate spikes. Pistillate spikes are cylindric, up to 2 inches long, stalkless or nearly so, and occasionally have a few staminate flowers at the tip (androgynous). At the base of each pistillate spike is a leaf-like bract that is longer than the spike, the bract of the lowest spike often over-topping the terminal spike. Bract edges are rolled in, the bract forming a slender tube barely 1 mm in diameter.

Leaves and stems:

Leaves are basal and alternate, mostly near the base, .7 to 2.2 mm wide, arching at maturity and may be much longer than flowering stem. The edges are rolled in, the leaf forming a slender, wiry tube barely 1 mm in diameter. Stem leaf sheaths are initially U-shaped, membranous whitish-green, the lower leaf sheaths often shredding with age forming a ladder-shape of thread-like fibers across the front. The ligule (membrane where the leaf joins the sheath) is thick, membranous, and longer than wide. Leaves are hairless though may be slightly rough at the tip end.

Bases are wrapped in a reddish sheath that is fibrous, often forming ladder-shapes of thread-like fibers. Stems are erect, 3-sided and smooth or slightly rough along the angles. Stems elongate up to 48 inches at maturity. Plants can create large colonies from long, creeping 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 to widely spreading and usually tightly crowded on the spike. Each pistillate spike contains 15 to 50 fruits.

Pistillate scales are lance to egg-shaped, dark purplish brown along the edge with a green midrib, either tapering to a pointed tip or the midrib extending to a short awn, somewhat hairy or rough around the tip edge, and are shorter than the perigynia. Perigynia are 2.8 to 5 mm long, 1.5 to 2.2 mm wide, densely hairy, many-nerved (obscured by the hairs), oval-elliptic, tapering to a very short, straight beak that has 2 small teeth at the tip. Achenes are 3-sided, 1.5 to 2.1 mm long, up to 1.5 mm wide, maturing to brown.

Notes:

Carex lasiocarpa is a common sedge of wet places, often growing in shallow water, and forming large colonies of fine, arching foliage.

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 lasiocarpa is in the Paludosae section; some of its common traits are: rhizomatous and forming colonies, leaves usually hairless, leaf sheaths often splitting into fibers and forming a ladder shape, leaves and sheaths with cross partitions between veins (septate-nodulose), basal sheaths red to purple and usually fibrous, terminal spike staminate, leaf-like bract subtending the lowest pistillate spike, perigynia usually hairy, beaked and toothed, achenes 3-sided in cross-section.

Carex lasiocarpa is distinguished from all other sedges by the combination of: hairy perigynia, strongly ladder-fibrous sheaths, basal sheaths red, wiry leaves and bracts, rolled along the edges creating a slender tube about 1mm in diameter. It most closely resembles Carex pellita, which has flat leaves with a prominent midvein, and less so Carex houghtoniana, which has larger perigynia (up to 6.5 mm long), flat leaves and a preference for drier, disturbed soils. North American plants have minor distinctions from European and Asian forms, and are designated subsp. americana.