I must admit that I did not know the name of this particular plant, but I checked with my "plant person," Susan and she identified it as a mandevilla. My reference photo was from a farm on the east end of Long Island. This is 5 x 5 inches.
More of the paintings by the participating artists can be found here. It is worth checking out.
I took a workshop in Jersey City two weeks ago and after the workshop was over we went out to sketch in the area. It was cold so I only ended up sketching for about 45 minutes and then finishing the color on this indoors.