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CommentsThis grass has been introduced everywhere and it has become ubiquitous. It is undoubtedly the most common bluegrass in Illinois. Distinguishing different bluegrass species (Poa spp.) can be difficult; this task often requires a 10x hand lens or a 30x field microscope while examining the lemmas of the spikelets. Because many different cultivars have been developed, Kentucky Bluegrass (Poa pratensis) is both genetically and morphologically diverse. Unlike some species in this genus, Kentucky Bluegrass forms a turf from long rhizomes. Its lemmas have 5 visible veins; the midvein and marginal veins are finely hairy on the lower half of each lemma, while the intermediate veins are hairless. Other bluegrass species are finely hairy along the intermediate veins as well, or they may lack fine hairs along the veins of their lemmas altogether. As a group, bluegrass species differ from many other grasses by the small tufts of webby hair that are usually found at the bottom of their lemmas.