Since the differences between grasses of the same species are relatively minor, the effects of possible trait combinations can be noted as small variations. The obvious question is if blending cultivars of a species makes for a somewhat better lawn, why not mix species and take advantage of the larger differences. That is the entire concept behind grass mixes. An example that makes the point is the popular mix of ryegrass and bluegrass. The two species are significantly different.
Perennial ryegrass is a bunch grass.
This means that if a spot of ryegrass turf is damaged it can be repaired only by reseeding or tillering. Conversely, bluegrass can self-repair a damaged spot of turf because it is a rhizomatous grass. A rhizome is a creeping stem or runner that extends outward from the main plant underground. The rhizome will send a shoot up to the soil surface while extending new roots downward. Some creeping grasses have above-ground runners called stolons .