But now say if the cross is put down like this (Colombian gold X Thai) X Afghani.
The Colombian gold and the Thai were already crossed together before the Afghani was introduced.
I get it if they are just reporting the linage but then all plants go back to the landrace they were crossed to. X1 + X2 +x3 +X4= X5 but (X1 + X2) + (X3 +X4) will not result in the same X5