One of the reasons I plant Zinnias in my yard every year is because I am fascinated with thick-stemmed flowers in an arrangement like this. One of my neighbors in the Pacific Northwest (many years ago) used a glass "frog" in a shallow glass dish and then inserted long-stemmed Zinnias in it.
This is what the glass frog looks like. I have two and found them in an antique store. When you place it in water, it seems to disappear.