Sucker branches on lemon tree
Hello, I have a small lemon tree, about 3 years old, that I started growing from seed. A few months ago two new branches grew out from lower down on the plant. I recently heard that lemon trees can sprout "sucker branches" that should be cut off to allow the rest of the tree to most efficiently grow and flower. Is this true? If so, how can one determine if a new branch is indeed a sucker branch? I have also included two pictures below showing where the branches are on the tree (note, however, one has no leaves). Could someone kindly tell me if these look like sucker branches, and if they should be removed?
Sucker branches are generally growing at the base of trees.