The basic diagram of the sentence is enlightening (see diagram on following page).
The subject of the first half of the compound sentence is the rod. The rod is to come from the root of Jesse. The interpretation of the passage has been given by Joseph Smith in Doctrine and Covenants 113:1–4.
The stem of Jesse is Christ. Jesse was the father of king David. The book of Revelation identifies Jesus in a similar manner. “I Jesus have sent mine angel to testify unto you these things in the churches. I am the root and the offspring of David, and the bright and morning star” (Revelation 22:1–6; see also 5:5). That the servant is Joseph Smith himself seems evident. President Brigham Young taught that Joseph was a “pure Ephraimite,” and this was confirmed by President Joseph Fielding Smith.
His being a pure Ephraimite does not necessarily mean he had only the blood of Ephraim in his veins, but may mean that he has the literal blood of Ephraim. This is also evidenced by the fact that his father, Joseph Smith Sr. was the Patriarch to the Church, which office belongs to “the oldest man of the blood of Joseph or of the seed of Abraham” (TPJS, 151). Joseph Smith would likely have had the blood of other tribes in his veins as well, since Israel lived among the Gentiles for hundreds of years. Certainly Joseph Smith had “much power” laid upon him, as D&C 113:4 states. He was given power to “translate the Book of Mormon” (D&C 20:8). Therefore Joseph Smith was the servant in the hands of Christ. All this fits well with the angel Moroni’s declaration to Joseph Smith that the eleventh chapter of Isaiah was about to be fulfilled.
The branch is the subject of the second half of the compound sentence. It was to grow out of the roots. To grow out of the roots suggests that it was to follow the work of the servant. The work of the servant was to bring forth the Book of Mormon. Joseph Smith was given “a gift to translate” and was commanded to “pretend to no other gift until my purpose is fulfilled in this; for I will grant unto you no other gift until [the Book of Mormon] is finished” (D&C 5:4). The Church was not organized until the Book of Mormon translation was completed. Therefore, it was the Church that was to grow out of the roots of Christ. “Branch” is capitalized in the KJV leading some to interpret it to refer to Christ, but it is not capitalized in the Book of Mormon. The roots seem to be the roots of the stem of Jesse [Christ], and a branch would grow from him, and would be his Church, but thus would not be him personally. Zenos mentioned that the branches of Israel would be grafted into the mother tree and would grow as mentioned in the allegory of Zenos (see Jacob 5:54–60).