Poa is a genus of bluegrasses. There are approximately 500 species of poagrasses. According to the Golf Course Superintendents Association of America, poa pratensis "is the species name for Kentucky bluegrass. Poa annua is annual bluegrass. There's also Poa trivialis (rough bluegrass) and Poa compressa (Canada bluegrass)."
Poa annua is easily the one best-known to golfers because it covers the putting greens at one of the world's most-famous courses, Pebble Beach in California.
Putting greens that use poa annua can sometimes have a splotchy or streaky look to them, because there are many different strains of poa annua. The more strains show up on a particular putting surface, the splotchier or streakier that putting green may appear. This is just a cosmetic affect, however, and does not impact the quality of the putting surface in terms of smoothness.
Poa annua does have one quality that some golfers don't appreciate. This includes Tiger Woods, who is not a fan of poa annua greens. That quality is this: Different strains of poa annua can grow at different rates during the sunny part of each day. That means that in the late afternoon, after a day of growing time, a poa annua green might be less smooth - bumpier - than it was throughout most of the day.
