After a number of experiments, I think the answer is no. It probably will create shadows correctly if you use a 3d model of leaves. I made the prop and then tried several kinds of lighting. Last I made a very bright white light pointing directly at the ground placing the transmapped square between the light and the ground with shadows turned on on each. Here's the render of the experiment. It might be worth trying one more time with a regular square, the single sided one can do strange things sometimes.

"Your work is to keep cranking the flywheel that turns the gears that spin the belt in the engine of belief that keeps you and your desk in midair."

Annie Dillard