What did the leaves look like? What condition were the leaves in in general? Where was the nursery?
My guess is what you saw a a chirimoya, or commonly known as a custard apple (A. retuculata).
The leaves were green and lush and on the plant, none falling off. About 8 to 9 inches long.
Below is a front and back photo of one leaf I took off.
Nursery (more like serious enthusiast) is in Jupiter
By the way, there were 3 trees. The earlier pictures were from the 1st and the leaf from the third. In case they are different trees
Do these photos help, is this a chirimoya or cherimoya