I am not sure if you have communicated with Barbara regarding this post. I was just out there yesterday but plan on going back sometime this weekend to plant flowers at my grandparents grave. I will see if I can come up with something for you.
I know exactly where the back row that abuts the Jewish Cemetery is. I assume your grave in question is 5 to 6 plots from the far right corner of St. Mary's. I do not recall a tree there but will check it out for you.