Grasses (Poaceae) are economically important mainly because they
Poaceae cereals represent cornerstone of human food security since Neolithic domestication: rice Oryza sativa, wheat Triticum aestivum, maize Zea mays, barley Hordeum vulgare, oats Avena, sorghum and millets provide staple starch endosperm rich in carbohydrates, proteins and B vitamins. Fruit type caryopsis integrates pericarp and testa fused. Family occupies temperate to tropical grasslands covering 40 percent land area, employing C3 and C4 photosynthesis pathways enhancing productivity water use efficiency. Fiber, spice or medicinal uses marginal compared to cereal provision, which drove civilization development, population growth sustaining billions worldwide daily calories.
Ref: NCERT Class 11 Biology, Chapter 5: Poaceae cereal crops economic importance grasses