12. Carex laeviconica Dewey

Pl. 39 j–m; Map 150

Flowering stems 40–120 cm long. Leaf blades 3–50 cm long, 3–8 mm wide, thin, dull green, flat, glabrous, the margins minutely roughened or toothed near the leaf tip. Leaf sheaths glabrous, the ventral side dull brown, lacking purplish coloration at the tip, the lowermost sheaths becoming dissected into threadlike fibers with age, the ligule about as long as wide and U-shaped. Staminate spikes 20–50 mm long, the scales 5.5–7.0 mm long, oblong-obovate, pointed or sometimes short-awned at the tip, smooth to minutely hairy along the margins, yellowish brown with the midrib tan and the margins white or nearly so. Pistillate spikes 25–75 mm long, 8–12 mm wide, the scales 4–10 mm long, ovate, pointed or tapered to a short, roughened awn at the tip, straw-colored to light brown with broad, thin, white margins, usually somewhat reddish tinged. Perigynia 5–9 mm long, glabrous, the teeth 0.9–2.0 mm long, often somewhat spreading, roughened on the inner side. Styles straight. Fruits with the main body 2.2–2.7 mm long, long-beaked, olive green. 2n=110. April–July.

Scattered in northern and central Missouri, mostly north of the Missouri River in the Glaciated Plains Division (Illinois to Montana south to Missouri and Kansas; Canada). Bottomland forest, bottomland and mesic upland prairies, sloughs, marshes, and margins of streams, ponds, and lakes, sometimes emergent aquatics.

Castaner and Reznicek (1988) reported an occurrence of the rare, sterile hybrid, C. laeviconica × C. trichocarpa, from Nodaway County at a small railroad prairie where neither putative parent was present. This hybrid, which occurs sporadically from Wisconsin to Illinois and Iowa, is intermediate between the putative parents in its sparsely pubescent perigynia and somewhat reddened leaf sheaths with the ventral surface sometimes becoming slightly dissected into fibers. Abandonment of the railroad at this imperiled site, followed by encroachment from nearby farms and widespread spraying of herbicides in the area, makes it unlikely that this unusual population will survive for much longer.