Sometime after planting fruit trees, someone with much more experience pointed out that the nasty spiked branches would never produce fruit, because they weren’t part of the fruit-bearing portion of the plant.
Instead, they were suckers growing from the root stock. You can sort of see where the two join, and there’s the sucker below.
The junction is much clearer on our lemon tree.
Lesson is: they are nasty things, obviously well worth removing!
Grafting requires an advanced education! For successful grafting… there’s much to learn.