Cyperus arundinaceus Linneaus, Sp. Pl. 1: 44. 1753 (as arundinacea)

Rhizomes 2–5 mm thick; internodes 2–5 cm. Culms 2–14, erect, unbranched, jointed, aphyllo-podic, terete, 20–100 cm × 2–5 mm; internodes hollow. Leaves: sheaths 2–14, bladeless, green, often with white dots in intervenal areas, with brown-hyaline 1–2 mm margin at mouth, firm; blades 3–15 per culm, 3-ranked, ascending, thick, 4–15 cm × 1–8 mm, ± leathery, glabrous; distal 5–20 leaves serving as bracts. Inflorescences 6–30 cm; spikes 1–17, in sheath axils, 2–5 cm. Spikelets 2-ranked, appressed-ascending to ascending-spreading, linear-lanceolate, flat, 1.5–3 cm × 1.2–2.5 mm; rachilla winged, wings hyaline, usually containing spongy tissue proximally, occasionally ciliate; scales decurrent, spongy-based, 5–9.5 × 1.4–2.4 mm, each subtending flower. Flowers 2-ranked, sessile; scales green with gold-hyaline margins; perianth bristles 6–9, 4–7.5 mm, stiff; stamens 3, longer than perianth bristles; pistils 1, 2-carpellate; styles 1, 3.8–6 mm, base persistent on achene; stigmas 2, 1–3.8 mm. Achene stipitate, 2–4 × 0.8–1.1 mm (excluding style base), shorter than perianth bristles.

Varieties 2 (2 in the flora): North America.

Lower Taxa

• Dulichium arundinaceum var. arundinaceum
• Dulichium arundinaceum var. boreale Lepage