Charles T. Bryson, USDA Agricultural Research Service, Bugwood.org
Kyllinga looks similar to nutsedge but grows tall with flowers that bloom from May to October. It's a perennial weed that forms as dense mats, resisting low mowing and thriving well in moist soils. It has dark green, narrow leaves with round seed heads that sit atop spikes. The leaves look a lot like grass but have a shinier appearance.
Getting rid of kyllinga comes down to maintaining the moisture levels in the soil and mowing low to the ground frequently. A postemergent herbicide like penoxsulam or halosulfuron can help to control the spread of this perennial with repeated applications. If it's left untreated, green kyllinga will continue to spread and cause an infestation throughout the turf.