The most telling identifying clue for this branch is the split between the good and the bad fruit. Of course the Book of Mormon allows us to make that connection between the Lamanites and Nephites as the two divisions of this branch - a division which (in the best of times) produced a "tame" and a "wild" fruit. Reading this example as the Lehites also allows us to confirm the "good soil" part of the allegory. As was promised to Nephi, "1 Nephi 2:20 And inasmuch as ye shall keep my commandments, ye shall prosper, and shall be led to a land of promise; yea, even a land which I have prepared for you; yea, a land which is choice above all other lands." (this promise was also made with Lehi, see 2 Nephi 12:5).
26 And it came to pass that the Lord of the vineyard said unto the servant: Pluck off the branches that have not brought forth good fruit, and cast them into the fire.
27 But behold, the servant said unto him: Let us prune it, and dig about it, and nourish it a little longer, that perhaps it may bring forth good fruit unto thee, that thou canst lay it up against the season.
Perhaps these two verses provide the strongest indication that the Lord/servant relationship is a literary device rather than an attempt to accurately depict the relationship between either the Father and the Son, or the Son and the prophets. We have here the Lord seeing the branches that do not bring good fruit, and deciding to destroy them. This is a natural assumption from a botanical viewpoint. However, the servant pleads to make the attempt to save these branches.
Rather than indicate any type of disagreement, this is a literary structure that allows for the continuation of the wild branches when the more logical thing would have been their destruction. The allegory has roots in botany, but reality in history, and the way the Lord works with his children is never so capricious as to completely destroy them when they first disappoint Him.