Rhododendron Horizon Monarch was painted on a stretched box canvas.
These are often hung unframed, though this one has been framed using a step frame inner to create an even space between the frame and the canvas.

John waited three years for this Rhododendron to come into flower, but the wait was well worth it when these huge flowers appeared commencing red in bud then slowly turning through pinks and orange to a pale yellow.
Catching the flower on camera in full sun allowed john to create this flower painting at a later date.