What's the Story Behind This?

On Saturday, my friend JB and I took in the Divine Redeemer Art Walk (Divine Redeemer is the name of the neighborhood, after a church and school that sit smack in the middle of it). I brought my dog Frodo along, and since like all dogs he considers the world his toilet, in short order I found myself carrying a rather malodorous plastic bag around, which I wanted to dispose of as soon as possible. We quickly took ourselves over to Boulder Park so I could deposit the thing in a public trash can. I immediately noticed this picnic table with a fresh, long stemmed rose sitting on it next to an upended water bottle. What the heck? Who abandons such a pretty bloom on a park table like this? What is the story here? Very odd!