Poa annua

Poa annua, or annual meadow grass (known in America more commonly as annual bluegrass or simply poa), is a widespread low-growing turfgrass in temperate climates. Notwithstanding the reference to annual plant in its name, perennial bio-types do exist. This grass originated as a hybrid between Poa supina and Poa infirma. Major chromosomal rearrangements after polyploidy have contributed to variation in genome size in Poa annua....read more on Wikipedia.