He shall cause them that come of Jacob to take root; rather, in the days to come Jacob shall strike root. Jacob, lately the vineyard, is now compared to a single vine, which becomes strong by striking its roots deep into the soil, and then, as a consequence, blossoms and buds, and fills the face of the world with fruit.
So the Israel of God, firmly rooted in the soil of God's favor, would blossom with graces of all kinds, and bring forth the abundant fruit of good works.