Poa is a genus of about 570 species of grasses, native to the temperate regions of both hemispheres. Common names include meadow-grass, bluegrass, tussock, and speargrass. Poa is Greek for 'fodder'. Poa are members of the subfamily Pooideae of the family Poaceae.
Poa
"Bluegrass": The seed pods go from green to purplish blue to brown. During the purplish blue phase the seed stems have a navy-blue coating.
Poa trivialis (rough meadow-grass), showing the ligule structure
Poaceae or Gramineae is a large and nearly ubiquitous family of monocotyledonous flowering plants commonly known as grasses. It includes the cereal grasses, bamboos, the grasses of natural grassland and species cultivated in lawns and pasture. The latter are commonly referred to collectively as grass.
Poaceae
Grass flowers
Drawing of Anomochloa marantoidea, one of the most primitive living grass species
Setaria verticillata from Panicoideae