Spikes:

A single staminate spike up to 2 inches long at the top of the stem, which almost always has a few to several pistillate flowers at the very tip (gynecandrous). Below this terminal spike are 2 to 4 slender-stalked, pistillate spikes that almost always have 1 or 2 staminate flowers at the base. These lateral spikes are widely spaced and arising singly from the nodes with a leaf-like bract at the base of the stalk. The stalk of the lowest spike is longest with the stalks becoming progressively shorter as they ascend the stem, the stalks initially erect to ascending, becoming drooping with maturity. Pistillate spikes are slender and cylindrical, up to about 1 inch long, erect and green at flowering time with white, thread-like styles, and the staminate spike with creamy yellow stamens.

Leaves and stems:

Leaves are basal and alternate, mostly near the base, 3 to 7 mm wide, shorter than the flowering stems, becoming arching. Stem leaf sheaths loosely wrap the stem and are papery, translucent whitish. The ligule (membrane where the leaf joins the sheath) is about as long as wide. Leaves are M-shaped in cross-section when young, mostly hairless on the upper surface, the underside and edges variously covered in long, white hairs which continue down the back of the sheath.

Bases are wrapped in a sheath that is hairy, not fibrous, and typically tinged red to purple, turning brown as they wither with age. Stems are slender, 3-sided and mostly smooth but rough along the angles in the upper plant. Stems become leaning to arching, elongating up to 30 inches at maturity and are longer than the leaves. Not all plants produce flowering stems. Plants form loose to dense clumps.

Fruit:

Fruit develops in late spring through mid-summer, the pistillate spikes forming clusters of seeds (achenes), each wrapped in a casing (perigynium), subtended by a scale. The empty staminate scales persist after fruit has dropped off. Pistillate spikes each contain 10 to 45 fruits that are often tightly arranged on the stalk.

Pistillate scales are egg-shaped, translucent white tinged brown with a green midrib that turns brown, pointed at the tip or the midrib extending to an awn less than 1 mm long, and are shorter than the perigynia. Perigynia are green tinged or dotted red, 3.5 to 5 mm long, 1.7 to 2 mm wide, 2-ribbed with 7 to 12 faint veins, hairless, loosely wrapping the achene, oval-elliptic, tapering at the tip with 2 minute teeth at the tip of the short beak, and tapering to the stalkless base. Achenes are 2 to 2.5 mm long, up to 1.5 mm wide, 3-sided in cross-section, and mature to dark brown.

Notes:

Carex formosa is found in wooded ravines and river valleys in only a handful of locations in Minnesota. According to the DNR, it is uncommon to rare throughout its range and its fragile habitat is a prime target for development, timber harvest, and livestock grazing. It was listed as a state Endangered species in 1996 and is currently listed as Threatened in Wisconsin.

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 formosa is in the Hymenochlaenae section; some of its common traits are: typically clump forming and forming loose colonies, leaves M-shaped in cross-section when young, spikes long and cylindric and drooping on slender stalks, terminal spike either all staminate or with a few perigynia (usually at the tip, occasionally the base), perigynia round in cross-section, 2-veined, beaked, the beak usually toothed, 3-sided achenes, often growing in woodlands.

Carex formosa is distinguished from other sedges in Minnesota by the combination of: hairy leaves, reddish basal sheaths, terminal spike mostly staminate with several perigynia at the tip, lateral spikes pistillate with 1 or 2 staminate flowers or empty scales at the base. It is most similar in appearance to another hairy Minnesota sedge: the also-rare Carex davisii, which has pistillate scales that are long-awned and often longer than the perigynia, and its lateral spikes are almost always all pistillate with no staminate flowers at the base. Overall, C. formosa also resembles other members of the Hymenochlaenae section (C. arctata in particular), but they are hairless and have all-pistillate spikes longer than 1 inch.