Poaceae (Gramineae)

Abstract

Abstract The grass family (Poaceae or Gramineae) is the fourth largest flowering plant family and contains approximately 11 000 species in nearly 800 genera worldwide. We currently recognise 12 subfamilies: Anomochlooideae, Pharoideae, Puelioideae, Bambusoideae, Ehrhartoideae, Pooideae, Aristidoideae, Panicoideae, Arundinoideae, Micrairoideae, Danthonioideae and Chloridoideae, and in these subfamilies we recognise 50 tribes and 81 subtribes. Grasses are well adapted to open, marginal and frequently disturbed habitats, and can be found on every continent, including Antarctica. A grass is characterised by having a caryopsis or grain, and the primary inflorescence is referred to as a spikelet with a lemma and palea. The incorporation of two photosynthetic or carbon dioxide assimilation pathways has led to the family's ability to occupy 31−43% of the Earth's surface in various climatic environments as the dominant component, the grasslands. Key Concepts: Rice, wheat, corn, barley, rye, oats, sorghum, pearl millet, finger millet and tef are widely cultivated grains. A grass is characterised by having a one‐seeded fruit known as a caryopsis or grain. The primary inflorescence is referred to as a spikelet with 1–many, two‐ranked bracts inserted along the floral axis or rachilla. The grass family is classified into 12 subfamilies, 50 tribes and 81 subtribes. A highly reduced floral structure and wind pollination has enabled the family to be extremely successful at planet‐wide radiation and colonisation. Incorporation of two photosynthetic carbon dioxide (CO 2 ) assimilation pathways has led to the family's ability to occupy 31−43% of the Earth's surface as a dominant component, the grasslands.