Print in red:
1x leaf.stl
2x border.stl

Print in white:
1x white.stl

The border and white have some supports that you'll need to cut away with a utility knife. The leaf should snap into the white part securely, but you might have to trim it a bit or sand it down (especially around the stem) and apply some force. The borders should slide easily but securely onto the white part.

I tweaked the models a bit to make it easier to assemble after printing, so they won't fit perfectly together on the computer. If you want to combine them into one model that can be printed on a dual-extruder machine it's probably easier to re-build it from scratch around the leaf. The white part is 32 mm wide, and the borders are each 16 mm wide. They are both 32.5 mm tall and 4 mm deep.

Rough print times on my Thing-O-Matic at 25 mm/s feedrate and 25% infill:
leaf.stl - 3 minutes
border.stl - 6 minutes each
white.stl - 11 minutes