Grasses
Grasses, common name for a large family of flowering plants that is economically and ecologically the most important in the world. The grass family contains about 635 genera and 9000 species, making it the fourth largest family after the legume, orchid, and composite families (see Composite Flowers ). IMPORTANCE All the world’s cereal crops are grasses, and thus the grass family is economically very important. The world’s 5 top crops produce more tonnage than the next 25 combined, and 4 of the top 5 are the cereals rice , wheat , corn , and barley . Human well-being depends on these few grasses, so even small crop failures of any one of them can produce widespread hunger and economic disruption. In addition, the family provides most of the world’s sugar (see Sugarcane ). Another member of the family, bamboo , is an important construction material as well as a food source; it also has been used in papermaking. Citronella, used both in perfumery and as an insect repellent, is an oil