Spiny rush

Juncus acutus

Tussock-forming, shortly rhizomatous perennial. Culms terete, 30–160 cm long, 2.0–4.0 mm diam.

Leaves terete, basal, shorter than culms, pungent; auricles absent; sheath yellow-brown to golden brown, adaxially coppery.

Inflorescence terminal or pseudolateral, diffuse, 4–13 cm long; flowers clustered, 1–6 per cluster and 5–50 clusters per inflorescence; involucral bracts 1 or 2, well-developed, 4–25 cm long, shorter than to longer than inflorescence. Tepals straw-brown, often tinged darker chestnut-brown; outer tepals (rarely 2.0) 2.5–3.7 mm long, shorter than or equalling inner tepals, often with narrow whitish margin near apex; inner tepals with broad white margin near apex. Stamens 6, shorter than outer tepals; anthers 1.2–1.7 mm long.

Capsule much longer than outer tepals, ellipsoid to ovoid, acute to acuminate, apiculate, yellow-brown to chestnut-brown; seeds membranous-tailed.

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