Spikes:

Separate staminate (male) and pistillate (female) spikes, with a single staminate spike ½ to 1 inch long at the tip of the stem. Below the staminate spike are 1 to 3 pistillate spikes, which may be close together or spread apart. Spikes are stalkless or nearly so and dark purplish brown at flowering time, staminate spikes with showy, creamy yellow stamens, pistillate spikes with long, white, thread-like styles. At the base of a pistillate spike is a scale-like bract that is shorter than the spike; the lowest spike is subtended by a leaf-like bract that is rather longer than the spike but usually shorter than the inflorescence (group of spikes).

Leaves and stem:

Leaves are basal and alternate, mostly near the base, 1 to 3 mm wide, erect to ascending and only a few inches long at flowering time but elongating up to 2 feet at maturity and becoming arching. Stem leaf sheaths are U to V-shaped and translucent whitish-green with vertical veins. The ligule (membrane where the leaf joins the sheath) is wider than long. Leaves are V-shaped in cross-section and hairless though may be slightly rough.

Bases are wrapped in a red sheath that splits and has thread-like fibers along the edges (a characteristic known as “fibrillose”), the fibers typically connected and may form a ladder pattern. Remnants of leaves from the previous year can persist and may be fibrous. Stems are slender, 3-sided and mostly smooth. Often only 4 to 6 inches tall at flowering time, the stems can elongate up to 18 inches at maturity. Not all plants produce flowering stems. Plants form loose clumps and create colonies from spreading rhizomes.

Fruit:

Fruit develops in mid to late spring, the pistillate spikes forming clusters of seeds (achenes), each wrapped in a casing (perigynium), subtended by a scale. The scales of staminate spikes are oval-elliptic, purplish brown with white edging and a blunt or pointed tip. The empty staminate scales persist after fruit has dropped off. Pistillate spikes each contain 4 to 12 fruits.

Pistillate scales are 2 to 4 mm long, 1.3 to 2.8 mm wide, egg-shaped with a blunt or pointed tip, dark purplish brown with a band of white around the edge, and are as long as or slightly longer than the perigynia. Perigynia are 2.3 to 3.4 mm long, 1.1 to 1.5 mm wide, fuzzy hairy at least in the upper half, lack veins, are generally urn-shaped, the body spherical, tapering towards the base, and a short straight beak that has 2 small teeth at the tip, though they may be obscure when immature. Achenes are 1.3 to 2.3 mm long, .9 to 1.4 mm wide, somewhat oval but widest above the middle, weakly 3-sided to round in cross-section, and mature to dark brown.

Notes:

Carex pensylvanica is one of the most common sedges in Minnesota, found throughout the state, and is one of the earliest blooming woodland plants in the spring—the creamy staminate spikes are rather showy and stand out amid the usually brown woodland floor. It grows in loose colonies with its small clumps a few inches to about a foot apart, and spreads primarily by rhizomes. Noted as a highly disturbance-tolerant species, an abundance of C. pensylvanica may be an indication of lack of diversity and degraded habitat.

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 pensylvanica is in the Acrocystis section (formerly Montanae); some of its common traits are: mostly dry habitat, hairless leaves, basal sheaths typically fibrous, small spikes often tightly clustered, terminal spike staminate, perigynia typically hairy, perigynia with 2 small teeth at the tip of the beak, achenes 3-sided to round in cross-section.

C. pensylvanica is distinguished from other members of Acrocystis by the combination of: its single, relatively large staminate spike, pistillate scales as long as or longer than the perigynia, hairy perigynia, perigynia beak less than half as long as the body, basal sheaths that are red and fibrous, leaves up to 3mm wide, loosely tufted with spreading rhizomes.