You may have thought that grass is grass but worldwide there are probably at least 10 000 different types of grass. Botanists, scientists who specialise in the study of plants, classify grass into four basic sorts – high, tall, mid and short. High grasses occur only on tropical grasslands that have high levels of rainfall. In the best conditions they can grow to heights of about 3 metres.
Tall grasses aren't quite as tall as high grasses – the tall grasses on the llanos in south America are usually about a metre in height and mid grasses between 30 and 90 cm. Short grasses such as the ones that dominate the dry belt of savannah just below the Sahara in Africa grow no taller than 8 cm usually.
These classifications are only according to size – within each broad type there are dozens of different species of grass. Some may be better adapted to different soil types, some may grow better near coastal regions.
There are about 9,000–10,000 or more species of grasses.