Adding columns together from .txt file

Hi,

I would like to know if there is a command to add columns of two files in one file.

For example:

File1:
Apple
Melon

File2:
Car
Tree

New File1&2:
Apple:Car
Melon:Tree

I was thinking about "cat file1 file2" but this isn't exactly that what I would like to do.

Thank you.