This perennial plant has woody rhizomes with many stems that form a clump. The stems terminate in a whorl of dark green leaf-like bracts and the small flowers (spikelets) are yellow-brown and appear in a small cluster from summer to autumn. 

Hardiness zones 9 to 10

Cyperus alternifolius is naturally found in Madagascar growing in well drained fertile moist light soils but tolerates wet conditions. It prefers an open sunny position and is frost and drought tender. 

The Umbrella Plant is grown for its foliage and clumping habit. It is planted in and around a pond for a jungle effect or a long a watercourse and in bog gardens. It is long-lived and will establish in 2 to 3 years but may spread into a large clump. If grown in cooler climates place in a hothouse with bright filtered light and high humidity. ID 483

Cyperus (si-PE-rus) alternifolius (al-tern-ee-FOH-lee-us)    

'Cyperus': from Greek kypeiros - a sedge; 'alternifolius': alternating leaves.
 
Cyperaceae (sy-peer-AY-see-ee)
Sedge Family