According to the Readers Digest, early settlers in Kentucky "were welcomed by field after field of tall grass with a blue cast ... [they] sold the seeds as 'bluegrass from Kentucky,' and over time, the state came to be known as 'The Bluegrass State.'"
Wikipedia tells us however that Kentucky bluegrass (Poa pratensis) "is not native to North America", but was brought there by the Spanish Empire in mixtures with other grasses. In Canada it's "considered an unwelcome exotic plant, and is indicative of a disturbed and degraded landscape."
Bluegrass music originated (according to Wikipedia) in the Appalachian region, which stretches from the Southern Tier of New York State to northern Alabama and Georgia – and doesn't actually include Kentucky. It gets its name from the Blue Grass Boys, who were the backing band of Country singer Bill Monroe – a native of Kentucky. According to Wikipedia, "Key developments occurred in Monroe's music with the addition of Lester Flatt and Earl Scruggs to the Blue Grass Boys in December 1945." Flatt and Scruggs came from Tennessee and North Carolina, respectively.
© Haydn Thompson 2021