Grass is a loosely-used term that can include non-grasses like sedges and rushes. Its scientific category is Poaceae under which are hundreds of different categories of grasses. When most people talk about types of grasses, they are speaking in general terms and are referring either the two types of cultivated grasses used for lawns, the warm season and cool season grasses, the ornamental grasses or native prairie grasses used in habitat restoration for large areas.
Cool Season Grasses
"Cool season grasses include Kentucky bluegrass, perennial ryegrass, turf-type tall fescue and fine-leaf fescues," according to the Cornell University Cooperative Extension. These grasses thrive in temperatures ranging from 65 to 75 degrees F which make them excellent choices for lawns in the northern part of the United States or other parts of the world with similar climates. Many lawns are made up of a mixture of these different varieties of grass with the bluegrass often being the most predominant.
Warm Season Grasses
These grasses grow during the warm season and then go dormant during cooler temperatures. This means that for several months of the year, they can turn brown and will not grow until the temperatures rise. There are many grasses that fall into this category but the most common are big bluestem, little bluestem, broomsedge bluestem, indiangrass, switchgrass, sideoats grama
and eastern gamagrass.
These grasses often include non-grass species such as sedges and thrushes, but usually refer to grass-like plants that are allowed to grow into full specimens without mowing. There are hundreds of varieties that are planted in landscaped areas for their distinctive plumage, their variegated leaves and many other reasons. These grasses originate from all over the world and range from creepers of a few inches to barrier grasses over 15 feet in height. The most popular are blue fescue, feather reed grass, fountain grass, giant Chinese silver grass, Indian grass, Japanese blood grass, maiden grass, northern sea oats, plume grass, porcupine grass, purple fountain grass, ribbon grass, silver banner grass and switch grass.