Different species of grasses have distinctive growth habits that will affect the appearance of turf.
Bunchgrasses, such as ryegrasses and most fescues, do not spread but enlarge through the growth of sideshoots or tillers. Bunchgrasses are easy to spot if your lawn thins out because the grass looks like small clumps or islands arising from the same crown. Bunchgrasses wear well, but do not form a solid sod. You may need to overseed frequently to fill in areas where the grass dies.
Grasses with rhizomes have underground runners that extend out to create new plants. It is best to plant rhizomes in mixtures with bunchgrasses. Rhizomes form strong sod and help quickly regrow injured areas. Kentucky bluegrass spreads this way.
Stolons spread by developing new plants from aboveground runners, known. This is typical of the vigorous growth of many southern grasses, and explains why they will crowd out other grasses and weeds when planted in an existing lawn.
Certain grasses, such as zoysia and Creeping fescue, use a combination of all three methods to expand.
Note: Mow mature seed heads otherwise some grasses are likely to spread through wind seed dispersal.
Other distinctions: Color and Other Important Characteristics, Variations in Texture, and Perennial versus Annual follow on the next few pages.