Northern Prairie Wildlife Research Center
Rusty Flatsedge (Cyperus ferruginescens)
- Family: Sedge (Cyperaceae)
- Flowering: August-October.
- Field Marks: This Cyperus differs by its red-brown spikelets and its orange-brown achenes. It lacks underground rhizomes.
- Habitat: Along rivers and streams, around lakes and ponds, in roadside ditches, mud flats.
- Habit: Annual herb with fibrous roots.
- Stems: Erect, unbranched, smooth, up to 2 feet tall.
- Leaves: Mostly near the base of the plant, elongated, narrow, smooth, up to 1/2 inch broad.
- Flowers: One per scale, with many scales crowded into flat spikelets; the spikelets red-brown, linear, up to 1 inch long.
- Scales: Ovate to oblong, red-brown, rounded or pointed at the tip.
- Sepals: 0.
- Petals: 0.
- Stamens: 3.
- Pistils: Styles 3; ovary superior.
- Fruits: Achenes triangular, obovoid, smooth, orange-brown.
- Notes: The achenes are eaten by waterfowl. The plant sometimes flowers when it is only 6 inches tall.
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