grass

Grass refers to members of the family Poaceae, a monocotyledon group that is among the most widespread and economically important plant families. There are thousands of species, ranging from small annuals to tall perennial grasses, and they occupy habitats from deserts to wetlands.

Grasses share common structural features. They have narrow leaves with a sheath that wraps the stem, a ligule at the leaf base, and joints called nodes on hollow stems. Many species spread vegetatively by underground rhizomes or aboveground stolons. The flowers form spikelets grouped into panicles or spikes and are typically wind-pollinated.

Grasses have diverse photosynthetic pathways; cool-season grasses mostly use C3 photosynthesis, while many warm-season species use C4, giving them efficiency in hot, sunny environments. Their root systems vary, often forming dense networks that help stabilize soil and store carbon. Grasses dominate many ecosystems, especially grasslands and savannas, and they regrow quickly after grazing or fire.

Humans rely on grasses for food, forage, and materials. The cereals—wheat, rice, maize (corn), barley, oats, millet, and sorghum—are major staple crops. Grasses provide livestock forage, turf for lawns and sports fields, and fiber and sugar sources from crops such as sugarcane and bamboo. They also play roles in erosion control and landscape ornament.

Management involves grazing, mowing, irrigation, and controlled burns. Grasslands face threats from overgrazing, habitat loss, invasive species, pests, and climate change. Sustainable management and restoration efforts aim to preserve biodiversity, productivity, and ecosystem services provided by grass ecosystems.