Identifying Rootstock Suckers On Mandarin Orange Trees

After bringing my Satsuma Mandarin Orange tree inside to escape a bitter cold snap, I somewhat neglected it. It got hidden behind some other large plants in my grow room. I only watered it from the front and could not see what was going on in the back of the tree.

After pulling it out to put back outside in the greenhouse, I noticed a couple of very large root suckers growing from the bitter orange rootstock below the graft. They had different shaped leaves and were loaded with thorns. This is what happens when you neglect pruning.