Tall fescue is a grass that is often used as a lawn grass, but will cause a weedy appearance when mixed with bluegrass or ryegrass. A bunch grass, it forms unsightly, coarse clumps in lawns. Also used in agriculture, it can invade home lawns from agricultural lands, ditches, or when lawns are planted on former agricultural land. Contaminated sod may introduce it, and it is often planted by the unwary homeowner by using low quality seed.