If you want a grass species that is easy to identify, choose Poa annua (annual meadow grass). It is nearly a certainty that you will have no difficulty because in deepest winter this grass will be the only one in flower. Look at any pavement or roadside edge in urban areas and you will see it everywhere.
Frosty weather makes no difference to its flowering. It is normally self-pollinating and seeds are viable within only a couple of days.
It is a highly variable species and can be annual or a short term perennial. Annual Meadow Grass is actually a hybrid of Poa infirma and P. supina, a fact only verified in 1957 by Prof. TG Tutin. It was a puzzle to think how these 2 species had hybridised, as supina is found in the mountains of central and northern Europe and infirma is found in arid Mediterranean regions.
It is suggested the 2 species got together in the Quatenary ice-age when climate change caused glaciers to move. So Poa annua is a relatively recent hybrid formed 2½ million years ago!
Unlike other grasses, P. annua has an innate ability to resist herbicides. It also seems to be able to develop specialised adaptations and growth forms which enable it to grow on dry golf courses or paddy fields.
It is the only non-native plant to have successfully established in the Antarctic and because of its close association with human activity, has spread throughout the world.
Sorry–no photo. Non needed, just take a look on the pavements.