Global description
Cyperus iria is an annual tufted sedge with trigonal smooth stems, more or less bushy, reaching 60 cm in height. Radical leaves, with membranous sheath, lanceolate linear leaf blade, flat or folded in V are shorter than the stems and are 2 to 5 mm wide. They are glabrous. The inflorescence is a simple or compound umbel more or less developed, yellowish, 5 to 10 floral stalks, 5 to 10 cm or more, with loose spikes consisting of 6-15 spikelets. The spikelets are small and dense, yellowish in colour.
First leaves
The first leaves are short and sheathing, lamina more or less arched or erect, with pointed apex, smooth faces, morphology similar to that of
C. difformis.
General habit
Plant erected in more or less developed tufts of 20-60 cm high.
Underground system
The roots are fibrous, yellowish brown or reddish in colour.
Stem
The stem is full, trigonal, thin, smooth, non-winged angles, 1 to 2 mm in diameter and 10 to 50 cm high.
Leaf
The radical leaves have a membranous sheath and a linear lanceolate leaf blade, folded in V or plane, 2 to 5 mm wide, all shorter than the flowering axes. The surfaces and the margin are smooth.
Inflorescence
The inflorescence is a simple umbel composed of 5 to 10 floral axis, 4 to 10 cm long, yellowish, underpinned by 3-5 leafy involucral, sufficiently developed spreading bracts, one is significantly longer than the other, 10 to 20 cm long. Spike loose, 1 to 3 cm long, comprising 6 to 15 spreading or erect spikelets.
Flower
The spikelets are linear, 6 to 12 mm long and 1.5 to 2 mm wide with many glumes, 1 to 1.5 mm long, slightly covered at maturity, suborbicular, mucronate obtuse apex, smooth keel, straw-colored to brownish yellow.
Fruit
The fruit is an ellipsoid achene briefly apiculate, similar to the glume, 1 to 1.5 mm long with a triangular cross section, reddish brown in colour.