20. Carex douglasii Boott

Pl. 34 n–r; Map 133

Plants dioecious, with slender, light brown to brown rhizomes. Flowering stems 6–35 cm long, bluntly trigonous, smooth. Leaf blades 5–15 cm long, 1.0–2.5 mm wide, thick, mostly curled outward or spreading. Leaf sheaths somewhat thickened at the tip. Staminate heads 15–40 mm long, irregularly ovate to elliptic in outline, the 7 to numerous spikes 8–15 mm long. Staminate scales 4.5–6.5 mm long. Pistillate heads (not present in Missouri plants) 15–45 mm long, irregularly oblong to ovate in outline, the 5 to numerous spikes 5–15 mm long, 4–8 mm wide, with 7–19 perigynia. Perigynia 3.5–4.5 mm long, including the 1.0–1.5 mm long beak, usually finely many-nerved on both sides, straw-colored, turning light brown to brown at maturity. Fruits 1.6–1.8 mm long. May–June.

Introduced, known only from the city of St. Louis (western U.S. from Iowa west to California and New Mexico; Canada; introduced in Missouri and Illinois). Adventive along railroads.

The plants collected during the 1950s in the St. Louis freight yards by Mühlenbach (Steyermark, 1963) are exclusively staminate.