First fruit (απαρχη). See on 1. Corinthians 15:20; 1. Corinthians 15:23. The metaphor is from Numbers 15:19. The LXX has απαρχην φυραματος, first of the dough as a heave offering.

The lump (το φυραμα). From which the first fruit came. See on Romans 9:21. Apparently the patriarchs are the first fruit.

The root (η ριζα). Perhaps Abraham singly here. The metaphor is changed, but the idea is the same. Israel is looked on as a tree. But one must recall and keep in mind the double sense of Israel in Romans 9:6. (the natural and the spiritual).