That would be known as an F2 (fillial 2). The initial cross (ak x sage) would be the F1. Backcrossing is when you have a plant with desirable traits but you don't have a male (or female) with those same traits to breed it with. In that case you would then have to outcross that plant to something with similar traits (or you could even add traits by outcrossing to a plant with whatever traits you want to add) and then backcross the progeny to the original plant with the desirable traits.
Definition for filial (as used in genetics)
Genetics . pertaining to the sequence of generations following the parental generation, each generation being designated by an F followed by a subscript number indicating its place in the sequence.
