412. Carex flava Linnaeus, Sp. Pl. 2: 975. 1753.
Yellow sedge, carex jaune
Carex flava var. fertilis Peck; C. flava var. gaspensis Fernald; C. flava var. laxior (Kükenthal) Gleason; C. laxior (Kükenthal) Mackenzie
Plants cespitose. Culms straight, 10–75 cm. Leaves of flowering stems shorter than to slightly exceeding culms, 5–30 cm × 1.6–4.7(–5.8) mm; ligules on distal cauline leaves truncate or rounded. Inflorescences: peduncles of terminal spikes 0.4–5(–9) mm; bracts to 18.5 cm × (0.7–)2–4.5 mm; inner band of sheaths truncate or concave. Spikes: proximal pistillate spikes (1–)2–5, contiguous or approximate, globose to elliptic, 8–22 × 7.5–12.7 mm; terminal staminate spikes sessile or pedunculate, 9–22 × 1.1–3 mm. Scales: pistillate scales reddish brown, 2.3–3.9 × 0.9–1.4 mm; staminate scales reddish brown, ovate, margins narrowly whitish hyaline, apex obtuse. Anthers 1–2.1 mm. Perigynia reflexed, bright yellow at maturity, 4–6.3 × 1–1.9 mm, apex gradually narrowed; beak 1.3–2.7 mm, forming angle of (15–)26–72° with body, scabrous. Achenes 1.3–1.7 × 0.9–1.2 mm. 2n = 60.
Fruiting Jun–Aug. Moist to wet habitats, such as open meadows, fens, partially shaded shrub carrs, swamps, on lime-rich soils; 0–2000 m; St. Pierre and Miquelon; Alta., B.C., Man., N.B., Nfld. and Labr., N.S., Nunavut, Ont., P.E.I., Que.; Alaska, Conn., Idaho, Ind., Maine, Mass., Mich., Minn., Mont., N.H., N.J., N.Y., Ohio, Pa., R.I., Vt., Wis.; Europe; Asia (Iran).