1. Phalaris arundinacea L. (reed canary grass)

Pl. 134 a–c; Map 545

Plants perennial, with long, scaly rhizomes, forming large clumps or colonies. Flowering stems 50–180 cm long. Leaf sheaths with the ligule 3–7 mm long. Leaf blades 4–40 cm long, 7–15(–20) mm wide. Inflorescences 7–30 cm long, dense, but usually interrupted and noticeably branched panicles, the branches strongly ascending. Glumes 3.5–6.5 mm long, glabrous or somewhat roughened, the midnerve (keel) unwinged (rarely very slightly winged). Sterile lemmas 1–2 mm long, linear, membranous or papery, not swollen or fleshy, hairy. Fertile lemma 2.7–4.5 mm long, narrowly ovate, hairy, at least toward the tip. Anthers 1.8–3.5 mm long. Fruits 1.5–2.0 mm long, elliptic‑obovate in outline, brown. 2n=14, 27, 28, 29, 30, 31, 35, 42, 48. April–August.

Scattered to common nearly throughout Missouri, but still apparently absent from portions of the Ozark Division (northern U.S. south to North Carolina, Oklahoma, and California; Canada, Alaska, Europe, Asia; introduced sporadically in Mexico and in the Southern Hemisphere). Banks of streams, margins of ponds and lakes, marshes, fens, and bottomland prairies; also pastures, roadsides, railroads, and moist, disturbed areas.

This highly variable, circumpolar species sometimes is planted for forage, hay, erosion control, or ornamental purposes, but Steyermark (1963) noted that it can be weedy and difficult to eradicate once established. He recorded it almost entirely from the Glaciated Plains Division and stated that it was common only in the northwestern and north‑central portions of the state. He suggested that a disjunct series of collections from Newton County made in 1954 might represent an introduction or escape from cultivation. Since that time, the species has spread tremendously in Missouri and presumably will eventually be found throughout the state. Populations south of the Missouri River are mostly found as large, dense stands along roadsides and the margins of ponds and lakes.