Cyperus serotinus

Herbs, perennial, stoloniferous; stolons terminated by tubers. Culms trigonous, 50-100 cm × 5-8 mm, glabrous. Leaves 3-6, V-shaped, 20-50 cm × 5-8(-10) mm. Inflorescences: spikes not appearing lateral, rays 5-8, 2-7(-12) cm; bracts 3-4, ± horizontal to ascending at 45°, V-shaped, 5-25 cm × 1.5-8 mm; spikes 1-4, ovoid, 2-4 × 2-3 cm; rachis 1-2.7 cm, smooth or hispidulous; rachilla persistent, wingless or with hyaline wings scarcely 0.1 mm wide. Spikelets 7-14, flattened, lanceoloid, 10-20 × 2-2.5 mm; floral scales 10-30, laterally dark brown to reddish brown, medially greenish, laterally 5-9-ribbed, ovate-deltate; anthers 3, 0.5 mm; styles 0.5 mm; stigmas 1.2-1.6 mm. Achenes brown, sessile, ellipsoid, 1.4-1.6 × 1.4-1.5 mm, apex obtuse, apiculate.

Fruiting summer. Tidal marshes; 0 m; introduced; Del., N.J., Pa.; Eurasia.