There are tallgrasses and shortgrasses, cool-season and warm-season growers, discrete bunchgrasses and continuous sodformers, annuals and perennials. With over 10,000 species, the grass family is the third largest plant family and incredibly diverse. However, all grasses have similar physical characteristics such as narrow, flat leaves that grow almost vertically. Grasses are flowering plants pollinated by the wind. This means they do not need special scents or colors to attract animal pollinators so the flowers are small and inconspicuous. Some parent plants also produce offshoots called tillers. These generate new plants which help to crowd out competitors.