Spikes:

Up to 25 small spikes, stalkless, erect to ascending, usually crowded at the tip of the stem with the lower slightly separated from each other, the group of spikes (inflorescence) straight and 1 to 2½ inches long. Spikes mostly have staminate (male) flowers at the tip and pistillate (female) flowers below (androgynous) but often some are all staminate or less often all pistillate. It is not unusual for spikes in the upper half (or more) to be all or mostly staminate. At the base of a lateral spike is an awned, scale-like bract, the lowest as long as or somewhat longer than the attending spike but much shorter than the inflorescence.

Leaves and stems:

Leaves are basal and alternate with 3 to 5 leaves on the lower half of the stem, 2.3 to 5 mm wide, up to 9 inches long and shorter than the flowering stems. Stem leaf sheaths tightly wrap the stem, the front green with obvious veins except white translucent at the tip, straight to slightly concave across the top, and the tip of the sheath extending 1 to 4.5 mm above the leaf base. The ligule (membrane where the leaf joins the sheath) is as long as or longer than wide. Leaves are hairless but rough along the edges, flat but V-shaped in cross-section when young, and erect to arching at the tip.

Bases are wrapped in a brown sheath that is not fibrous. Stems are slender, 3-sided, rough textured on the upper stem, erect, elongating up to about 4 feet at maturity. Non-flowering stems are common. Plants form loose to dense colonies from long, creeping, dark brown-black rhizomes.

Fruit:

Fruit develops in late spring through early summer, the pistillate spikes forming clusters of seeds (achenes), each wrapped in a casing (perigynium), subtended by a scale. Spikes usually contain 3 to 25 fruits that are appressed to ascending and overlapping on the stalk.

Pistillate scales are broadly lance to egg-shaped, light brown to straw-colored with whitish edging and a green midrib drying to light brown, tapering to a pointed tip, slightly shorter than and about as wide as or wider than the perigynia. Perigynia are 2.5 to 4.6 mm long, 1.3 to 2 mm wide, green turning golden to brown at maturity, more or less convex on the front and flattened on the back, strongly veined on both surfaces, hairless but with minute serrations along the edges on the tip half, loosely wrapping the achene, the body narrowly egg-shaped, rounded at the base, the tip usually gradually tapered with 2 distinct teeth at the tip, the beak .4 to 1 mm long. Achenes are 1 to 1.8 mm long, .7 to 1 mm wide, brown to reddish-brown, flattened lens-shaped.

Notes:

Carex sartwellii is a common species found in open, wet places, sometimes in standing water, and is present in about ¾ of Minnesota. Flowering stems are sometimes few, the sterile shoots dominating and usually a little taller than fertile shoots. When present, heads covered in the pale, empty scales of staminate flowers can really stand out.

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 sartwellii is the lone member of the Holarrhenae section in Minnesota; some of its common traits are: not clump-forming, long-rhizomatous, basal sheaths brown, stem leaf sheath fronts green-veined and not significantly different from the back, leaves V-shaped in cross-section when young, leaves hairless, spikes mostly with staminate flowers at the tip (androgynous), lateral spikes androgynous or unisex, perigynia flattened in cross-section, veined on both sides, winged along the edges, rounded at the base, beaked with 2 teeth at the tip, flattened lens-shaped achenes.

Carex sartwellii is distinguished from other sedges by the combination of: not clump-forming, colony forming from blackish-brown rhizomes, widest leaves 5mm wide or less, stem leaf sheaths green and veiny on the front, the whitish tip of the sheath extended 1 to 4.5mm above the leaf base, spikes congested at the tip of the stem, spikes with staminate flowers at the tip (androgynous) or unisex, perigynia 2.5 to 4.6mm long, distinctly nerved on both sides, minutely winged along the edges except sometimes near the base. While the green, veiny leaf sheaths of C. sartwellii are a distinctive trait, other species with a somewhat similar inflorescence are Carex siccata and members of the Divisae section, all of which are also rhizomatous, but have white, translucent and papery leaf sheaths. Members of the Heleoglochin section also have similar inflorescences, but are densely clump-forming and have copper-colored dotted or solid colored leaf sheaths.