R10c2, r11c1,3,18, r12c2,3,17,18,19, r13c18, r16c3,5,14, r17c6,9,10,12,15 that gives you the two isolated leaves and the base of the tree, the tree has four branches, two to the left, two to the right.
Yeah. This is hell to solve. Ill leave some hints that should hopefully make it a bit easier for others, in addition to Not A Conspiracy's (All of their hints are indeed correct).
r1c6, r2c7, r3c8,14 r4c1,8,13 r5c2,3,7,14.
Thanks for the hints - I would NEVER have worked this out.