noun
: any of several large plants of the genus Scirpus: as
a. : a tall Eurasian sedge ( S. lacustris ) with naked terete stems and a compound umbel of numerous capitate spikes
b. : a bulrush ( S. validus ) of tropical America and southern United States with a stout scaly reddish rhizome, thick pliable culm, and spikelets in close fascicles or glomerules ; also : a bulrush chiefly of northern No. America that is a variety ( S. validus creber ) of the above distinguished especially by lax panicles