Saplings from Extra Trees with a 2x2 or higher girth don't spawn correctly, this happens if the sapling has the higher girth normally or if you change via serum or the genesis item.

They will for some reason spawn correctly if you use bone meal on the sapling in the N-W conner, for 2x2, but if you use the bone meal on any other sapling they won't spawn correctly.

• Minecraft : 1.12.1
• Forge : 14.22.0.2456
• Forestry :1.12-5.5.0.169
• Binnie : 1.12-2.3.0.32

Thanks for the report!
This was an issue in Forestry a long while ago, we can probably copy the logic from there.

Just had the exact same issue with Great Cedar same as illustration above.
Trees grows off 1 block south on positive x,z coordinates.