I have positively seen this in urban gardens. I did not know it was a cultivar of something in nature. This one in particular looks more like the cultivar to me. It is very possible that seeds were washed into the urban creek Upham brook that flows into Bryan park and established itself here. I have seen the same thing happen with Liriope muscari, a species of low, herbaceous flowering plants from East Asia, link to this plant here, http://www.missouribotanicalgarden.org/PlantFinder/PlantFinderDetails.aspx?kempercode=l100
I have seen a great blue in this exact same spot, multiple times before. I am not sure if it's the same one though, although I'm not sure if herons habitually rest in the same spot, or have popular heron meet-and-greets! A quick web-search turned this up, http://www.heronconservation.org/resources/Behavior_Terminology.pdf
There was two of them flying around Young's pond. They were making a loud, dry rattle in varying length and intensity. I did a quick web-find that says, "A long rattle often indicates alarm, aggression or excitement. Kingfishers are territorial and call often in flight along shorelines." http://www.birdjam.com/birdsong.php?id=45 Not sure if the source is noteworthy. Audubon.org says, "Loud, penetrating rattle, given on the wing and when perched." http://birds.audubon.org/birds/belted-kingfisher The other two photos were converted to monochrome because of the poor color quality, which would not help in the ID.
It was curious of me and did not seem to be afraid of me either, to which allowed me to get some pretty cool shots!
On Right by Stump.