There are a couple ways of producing your wedding tree, below are some ideas I came across. Cute, right!?! Of course I would provide the tree print with a custom wedding monogram to match.
Glue dots brand are my recommended dot of choice and can be found at your local craft/office supply store.
Above are thumbprint tree designs; guests will stamp their thumbprint using provided ink pads (that won't leave ink on them after washing of hands) on an open tree branch and then sign their name next to it- and ta-da, your tree is complete! Ink for these "fingerprint" leaves can be found at JoAnn Fabric.