Spikes:

One to 5 spikes, all thick cylindric, ¾ to about 1½ inches long, about ½ inch in diameter. The terminal spike is mostly pistillate (female) with a few staminate (male) flowers at the base (gynecandrous). Lateral spikes, when present, are usually all pistillate on slender, erect to ascending stalks, sometimes with staminate flowers at the base. Spikes may be clustered together at the tip of the stem but are not typically crowded. At the base of each lateral spike is a leaf-like bract, usually much over-topping the terminal spike.

Leaves and stems:

Leaves are basal and alternate, 3 to 10 mm wide, mostly longer than the flowering stem. Stem leaf sheaths are papery and fragile, whitish to light brown and tightly wrap the stem. The ligule (membrane where the leaf joins the sheath) is longer than wide. Leaves are hairless, smooth, V-shaped to flat in cross-section, mostly arching.

Basal sheaths are brown to reddish-brown and not fibrous. Stems are erect to ascending to arching, 3-sided in cross-section, and mostly smooth. Stems can elongate up to about 3 feet at maturity. Plants typically form dense clumps from short rhizomes and vegetative shoots are common.

Fruit:

Fruit develops in early to mid-summer, the pistillate spikes forming clusters of seeds (achenes), each wrapped in a casing (perigynium), subtended by a scale. Perigynia are widely spreading (pointing outward) to ascending (pointing upward) and tightly packed on the spike. The largest spikes contain 50+ fruits.

Pistillate scales are lance-oblong, initially white turning brown to red-brown, with a green midrib that is blunt to pointed at the tip and not awned, 2.3 to 5.5 mm long, shorter than the perigynia, mostly hidden by the perigynia. Perigynia are 5.5 to 7.8 mm long, 2 to 3 mm wide, green to brownish at maturity, hairless, several-ribbed (best seen when dry), inflated, the body an inverted cone-shape, abruptly tapering to a slender, slightly bent beak 2.3 to 3 mm long that has 2 obscure teeth at the tip. Achenes are 2 to 2.6 mm long, 3-sided, maturing to brown, oval-elliptic often with somewhat concave sides.

Notes:

Carex typhina is a rare sedge in Minnesota, limited to mature, floodplain forest in the Mississippi and St. Croix river valleys, where it reaches the northwest edge of its range. According to the DNR, its habitat is most at risk from water level management of the river systems, which is a boon to the shipping industry but bad for plants that depend on cycles of spring flooding and subsequent receding waters. It was listed as a Special Concern species in 1996.

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 typhina is the lone member of the Squarrosae section in Minnesota; some of its common traits are: clump forming or not, long to short-rhizomatous, hairless leaves, basal sheaths brown to reddish-brown, sheaths papery and fragile, 1 to 9 spikes, terminal spike all staminate or with staminate flowers at the base (gynecandrous), lateral spikes stalked and pistillate or gynecandrous, long leaf-like bract subtending the lowest pistillate spike, largest spikes with 50+ perigynia, perigynia ascending to spreading, hairless, inflated, inverted cone shape with an abrupt taper to a long, slender beak, beak toothed, achenes 3-sided in cross-section sometimes with a persistent style.

Carex typhina is distinguished from all other Minnesota sedges by the combination of: clump-forming, spikes thick cylindric, often a single spike, terminal spike gynecandrous but mostly pistillate, lateral spikes pistillate or gynecandrous, 50+ perigynia densely crowded, inflated, inverted cone shape with an abrupt taper to a long beak pointing upwards or outwards (not downwards), 3-sided achenes. It may resemble some members of the Vesicariae section, which have all-staminate terminal spikes.