seed of the land - not a foreign production, but one native in the region; a son of the soil, not a foreigner: Zedekiah, uncle of Jehoiachin, of David’s family.
in a fruitful field - literally, a “field of seed”; that is, fit for propagating and continuing the seed of the royal family.
as a willow - derived from a Hebrew root, “to overflow,” from its fondness for water (Isa 44:4). Judea was “a land of brooks of water and fountains” (Deu 8:7-9; compare Joh 3:23).