Yellow Nutsedge (Cyperus esculentus)

Flower stage of erect, persistent, colonial plant as seen June through September.  Stems are triangular, borne individually from tuber or basal bulb.  Leaves 3-ranked, mostly basal, blades linear, 3/16 inch wide, with blade gradually tapering to a sharp point.  Seed head umbel-like, with yellowish-brown to straw colored spikelets.