Cogongrass

Imperata cylindrica (Poaceae) is a rhizomatous perennial grass native to Africa, Europe, and Asia, now classified as one of the world's most invasive plants. It reaches 2 to 4 feet tall and spreads aggressively via scaly rhizomes that penetrate 2 to 4 feet deep. The leaves grow up to 30 inches long with finely toothed margins embedded with silica crystals. In temperate gardens it rarely flowers, but in tropical regions produces fluffy white panicles to 16 inches.

The ornamental cultivar 'Red Baron' (Japanese blood grass) is grown for its burgundy-red foliage, but the species itself is an extremely aggressive invader that regenerates after fire and suppresses competing vegetation. It tolerates full sun to part shade and adapts to clay, loam, and sand. Once established, it is drought tolerant. Caution is warranted: in warm climates, even 'Red Baron' can revert to the green-leaved invasive type. Control is extremely difficult due to the deep rhizome network. Hardy in Zones 5a to 9b.