There are thousands of varieties of lawngrass.   Each type of lawn grass is adapted to specific conditions of precipitation, temperature, and sun/shade tolerance.

Breeders are constantly creating new and improved varieties of the base list of lawngrass species.

The two basic categories are cool season grasses and warm season grasses.

Cool Season Grasses

Cool season grasses start growth at 41 °F, and grow at their fastest rate when temperatures are between 50-77 °F, in climates that have relatively mild/cool summers, with two periods of rapid growth in the spring and fall. They retain their color well in extreme cold and typicaly grow very dense, carpetlike lawns with relatively little thatch.

Examples of cool season grasses:

• Bluegrass
• Bent Grass
• Ryegrass
• Fescue Grass
• Buffalo Grass
  

Warm Season Grasses

Warm season grasses only start growth at temperatures above 50 °F, and grow fastest when temperatures are between 77 °F and 95 °F, with one long growth period over the spring and summer. They often go dormant in cooler months, turning shades of tan or brown. Many warm season grasses are quite drought tolerant, and can handle very high summer temperatures, although temperatures below 5 °F can kill most warm season grasses. 

Examples of warm season grasses:

• Zoysia Grass
• Bermuda Grass
• Centipede Grass
• Bahia Grass
• St. Augustine Grass

 From Wikipedia, the free encyclopedia