Inspirational (or Fanatic) Citrus Grafting
The man who created this tree is a member of the Philippines Raw Fruit mailing list. Amazing work. He also has some fantastic grafting manuals online.
" ... This is a testament of how adaptable citrus cultivars are and how most of them are graft compatible, and yet they all can produce tremendous diversity of fruits in one tree!
I have to admit, that I have grafted more than 100 cultivars into this one. I have only found 81 labels still attached, so officially it is an 81-n-1 citrus tree ..... "